DTI 26-01-R-001 SAFETY FACTOR ANALYSIS FOR CENTRIFUGE SYSTEMS FINAL TECHNICAL REPORT by A N...

AD, A23 9 838 AD___

REPORT 26-01-R-001

SAFETY FACTOR ANALYSIS FOR CENTRIFUGE SYSTEMS

FINAL TECHNICAL REPORT

by

A N Schofield and R S Steedwan

24 July 1991

United States Army

EUROPEAN RESEARCH OFFICE OF THE U.S. ARMY

London England

CONTRACT NUMBER DAJA45-90-C-0018

ANDREW N SCHOFIELD & ASSOCIATES LTD9 LITTLE ST MARYS LANE,

CAMBRIDGE CB2 1RR, U.K.

Approved for Public Release; distribution unlimited

DTI^ELECTE

AUG19 199,N

SEtC URITIY_ C LASSIF ICA TION OF THIS PA6 E

REPORT DOCUMENTATION PAGE O 704Zo,.es__________________________________________I fip Oafe Jun3J0. I

14. REPORT SECURITY CLASSIFICATION I b. RESTRICTIVE MARKINGS

UNCLASSIFIED2a. SECURITY CLASSIFICATION AUTHORITY 3. DISTRIOUTIONIAVAILAILITY OF REPORT

_____________________________________ APPROVED FOR PUBLIC RELEASE:2b. DE CLASSIFICATION / DOWNGRADING SCHEDULE DISTRIBUTION UNL IM ITED

4. PERFORMING ORGANIZATION REPORT NUMBER(S) S. MONITORING ORGANIZATION REPORT NUMBER(S)

26 - 01 - R - eel R&D 6396-EN-01

6a. NAME OF PERFORMING ORGANIZATION 6b. OFFICE SYMBOL 74, NAME OF MONITORING ORGANIZATIONANDREW N. SCHOFIELD & (it applicable) USARDSG-UKASSOCIATES (ANS&A)_______________________________

6c. ADDRESS (City, State, and ZIP Code) .7b. ADDRESS (City, Staite, and ZIP Code)9 Little St. Mary's Lane PSC 802 BOX 15Cambridge, CB2 lRR, UK FPO AE 09499-1500

Sa. NAME OF FUNDING/ SPONSORING 8b. OFFICE SYMBOL 9. PROCUREMENT INSTRUMENT IDENTIFICATION NUMBERORGANIZATION I(it applicable) DAJA45- 90--C=0018'

USAE WATERWAYS EXPERIMENT STAT iN WES/GEOT. .. _____________________

kc. ADDRESS (City, State. and ZIP Code) 10. SOURCE OF FUNDING NUMBERS

P0BO 61PRO6RAM PROJECT ITASI ~ WORK UNIPOBX61ELEMENT NO. NO. No ACCESSION

VICKSBURG, MS 39180-0631 P1102A IL161102BH 1701 AR

11, T I TL (include Security Classification)U) SAFETY FACTOR ANALYSIS FOR CENTRIFUGE SYSTEMS

12 PERSONAL AUTHOR(S)

A.N. SCHOFIELD AND R.S. STEEDMANIla.TYPEOFREPORT libTIME COVERED 114. DATE OF REPORT (Year, Month, Day) 115. PAGE COUNT

FINAL TFROMApr 90 TOJUL%L 1991,__July. 24th- 516. SUPPLEMENTARY NOTATION

17. COSATI CODES 18. SUBJECT TERMS (Contrinue on reverse It necessary anid identify by block number)

FIELD GROUP SUB-GROUP1U

19. ABSTRACT (Continue on reverse of necessary and identity by block number)

ANS&A recoimmends that WJES should buy the Acutronic 684-1 centrifuge andoptional items apart from the additional large platform listed in thei~rProposa~l 9530A (February 1991), subject to Quality Assurance (QA)procedures which will involve ANS&A in all stages or design, manufacture,installation, commissioning and operation of the centrifuge facility atWES.

Mlatters requiring clarification include the air conditioning and locationof the containment structure, the crane and alterations to the existingoffice and control buildings, and the management structure.

Continued on reverse ..

20 DISTRIBUTION/AVAILABILITY OF ABSTRACT 21 ABSTRACT SECU4ITY CLASSIFICATION

0 UNCLASSIFIEDIUNLIMITED GO SAME AS APT. M~ OTIC USERS UNCLASSIFIED22s, NAME OF RESPONSIBLE INDIVIDUAL 22b TELEPHONE (icludel Area Cd)Jac OFFIE SYMBOL.

JERR C.COMAI I071-40P-733118490 A14XSN-BKI-RF

O FORM 1473.84 MAR 83 APR edition may be used until exhaulled SIECURITY Ck SIFIATION F002141 PA(

All other editIonil ae obsolete UNCLASSI FIED

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Block 19. ABSTRACT .... continued from front

ANS&A envisage that their Project Engineer in France will achieve a closecollaboration with Acutronic France during the final design process.inspecting and reviewing all phases of des ign and manufacture within welldefined procedures for Quality Assurance-11

Integrated Quality Assurance will cover the centrifuge, buildings.instrumentation and equipment, the introduction of safe operatingprocedures, and the management of change. It is anticipated that anoutstanding centrifuge with a unique range of capabilities will be inoperation under full control by WJES by December 1994.

2

Ji~

ANS&A Report 26-01-R-001

REPORT DOCUMENTATION PAGE

ERO Proposal No.: R&D 6396-EN-01 Contract No.: DAJA45-90-C-0018

Title of Proposal: Safety factor analysis for centrifuge systems

Name of Institution: Andrew N Schofield & Associates Ltd.,9 Little St Marys Lane,Cambridge CB2 1RR, U.K.

Principal Investigator: Dr Andrew N Schofield

A 1 Schofield R S Steedman 24 July 1991

NTIS GRA&IDTIC TAB 0Unannounced 0

By--Distrlbution/Availability Coaes

Avail and/or

D is ,,, ,, ,


SUMMARY

ANS&A recommends that WES should buy the Acutronic 684-1centrifuge and optional items apart from the additionallarge platform listed in their Proposal 9530A (February1991), subject to Quality Assurance (QA) p:ocedures whichwill involve ANS&A in all stages of design, manufacture,

installation, commissioning and operation of the centrifugefacility at WES.

Matters requiring clarification include the air conditioningand location of the containment structure, the crane andalterations to the existing office and control buildings,and the management structure.

ANS&A envisage that their Project Engineer in France willachieve a close collaboration with Acutronic France duringthe final design process, inspecting and reviewing all

phases of design and manufacture within well definedprocedures for Quality Assurance.

Integrated Quality Assurance will cover the centrifuge,buildings, instrumentation and equipment, the introductionof safe operating procedures, and the management of change.It is anticipated that an outstanding centrifuge with aunique range of capabilities will be in operation under fullcontrol by WES by December 1994.

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LIST OF KEYWORDS

centrifugetestmodelcapabilitiesqualityassurancecontainmentbuildingsequipmentinstrumentationsafety

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CONTENTS

Page

Report Cover Sheet iReport Documentation PageSummaryList of Keywords ivContents v

1.0 DEVELOPMENT OF CENTRIFUGE MODEL TEST CAPABILITIES 1

1.1 Acutronic Proposal 9530A (February 1991) 1

1.2 Containment Structure 51.3 The crane 71.4 Alterations to the existing office

and control building 71.5 Programme for future ANS&A research contracts 71.6 Commissioning by Acutronic 91.7 Custodianship by ANS&A 9

1.8 Management Structure 101.9 Announcement 11

2.0 DETAILED SPECIFICATION OF THE CENTRIFUGE 13

2.1 Introduction 132.2 Definition of a set of technical

and performance specifications 13

3.0 QUALITY ASSURANCE: GENERAL REQUIREMENTS 26

3.1 :ntroduction 263.2 implementation 273.3 Project QA files 283.4 Document control 283.5 Calculations 293.6 Reports 293.7 Audits and nonconformances 293.8 Documentation 303.9 Application of procedures 30

4.0 QUALITY ASSURANCE PROCEDURES FOR THE CENTRIFUGE 32

4.1 Background 324.2 Design and fabrication phases for the LCPC

centrifuge 334.3 Procedures for the design and fabrication

phases for the WES centrifuge 34

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4.4 Requirements for Acutronic 364.5 Acceptance and commissioning tests for the

WES centrifuge 37

S.0 INTEGRATION OF QUALITY ASSURANCE OVER THE CENTRIFUGE,

BUILDINGS, INSTRUMENTATION AND EQUIPMENT 40

5.1 Introduction 405.2 Quality assurance and project management 405.3 Procedures 41

6.0 QUALITY ASSURANCE PROCEDURES FOR INSTRUMENTATION

AND EQUIPMENT 42

6.1 Introduction 426.2 Fundamentals 42

6.3 Requirements of equipment QA 436.4 Calculations for safety of equipment 44

7.0 SAFETY OF OPERATIONS 45

7.1 Introduction 457.2 Safety information 467.3 Hazards analysis (HAZAN) 46

7.4 Management of change 477.5 Normal operating procedures 547.6 Training 547.7 Emergency response and control 557.8 Investigation of accidents 557.9 Audit 557.10 Disclosure of information regarding safety 56

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1.0 DEVELOPMENT OF CENTRIFUGE MODEL TEST CAPABILITIES

1.1 ACUTRONIC PROPOSAL 9530A (FEBRUARY 1991)

During the period of ANS&A's Phase 1 project questionshave been raised and answered over the specification ofthe Acutronic 684-1 centrifuge and its potential rangeof capabilities. Changes have been made to the outline

design which reflect more closely the needs of WES increating new capabilities for physical modeling. TheWES draft Miscellaneous Paper which studied thefeasibility of a WES centrifuge included contributionsfrom a number of authors at WES who expressedintentions to undertake centrifuge model tests ataccelerations above 200g. The centrifuge as nowproposed can test a 2 tonnes mass at up to 350g, and a4 tonnes mass at up to 150g, on a 1.3 m x 1.3 mswinging platform.

ANS&A recommends that the operations of this centrifuge

be divided into two ranges of acceleration. Thereshall be a normal range of operation up to anacceleration designated as g-normal, or gnorm = 280g ,and there shall be a maximum range of operation up toan acceleration gmax = 350g . The revised Acutronic

Proposal 9530A, dated February 1991, has on page 16 aload/acceleration operating map from which permittedloads in the gnorm and gmax ranges should bededuced: the scale on the curved portion of this map isunusual and Acutronic will be asked to provide a largerscale map or table of values, more precisely defining

the permitted load, when their design becomes more

precisely detailed. in some cases the magnitude of theload may depend on the area of the platform to whichthe load is applied.

Consideration should be given in detailed design to the

possibility of increasing the 'head-room' between theplatform and the boom divider. More space will bevaluable for example in tests with pile driving.

Consideration must also be given in the detailed designto the use of space above the central axis of the

centrifuge for mounting flight computers to handle A/Dconversions and multiplexing of data and to control

in-flight systems.

ANS&A's second interim report included an Appendix Cwith the title "Establishing a new Centrifuge Facility"

1!


by Dr R N Taylor; the proceedings of Centrifuge 91included an article by Professor M F Randolph et al.

I ,

with the same title. In these papers the authors referto experiences with recently installed Acutronic 661centrifuges at the City University, London and at theUniversity of Western Australia, Perth. It isimportant that, during the detailed design of the WESfacility, Acutronic should take account of all commentsmade on the performance of mechanical and electricaland control equipment, and ensure that problemsencountered in the past are overcome in the design ofthe centrifuge for WES.

The contracting officer of WES will note that in thefollowing pages of this report a procedure is set outfor the review and acceptance by ANS&A of AcutronicFrance's detailed design documents. The contract thatis entered into by WES and Acutronic USA should reflectthe essential research and development that is involvedin the creation of a facility for WES that will involveadvances in the state of the art. The contract shouldrefer both to the transfer of existing technology fromAcutronic France to Acutronic USA and from ANS&A to

WES, and to the new advances of technology that areintended in the creation of a potentially outstandingcentrifuge and a world class centrifuge centre. Thecontract should be written so as to reward closecooperation and high achievement of the partiesinvolved.

ANSA propose the selection of a WES Project Manager,and of a procedure by which ANS&A assists WES inachieving Quality Assurance and Quality Control of theproject. The contracting officer will define themanner in which the achievement of successive stages inthe Quality Assurance and Control procedures is used bythe WES Project Manager to control the succession ofpayments to Acutronic USA under their contract withWES.

The revised Acutronic Proposal 9530A, dated February1991, consists primarily of an outline specification ofthe centrifuge and its associated and optionalequipment but it also introduces a conceptual designfor the containment structure.

M F Randolph, R J Jewell, K J L Stone and T A Brown (1991),

Establishing a new centrifuge facility, ProceedingsCentrifuge 91, Boulder, June 11-13, Balkema.

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In this section comment is made on the optionalequipment proposed by Acutronic. Section 1.2 addressesthe question of the containment structure and section2.0 provides a detailed set of technical andperformance specifications which Acutronic should berequired to meet.

ANS&A recommend that the Acutronic centrifuge shouldbe bought together with all optional items, with theexception of the large platform, subject to QualityAssurance as discussed below.

optional equipment (references as Proposal 9530A)

111.2,1 Air conditioning

There are two causes of temperature variationto consider. In a typical long durationcentrifuge test on a clay specimen theinitial warming up of the pit, centrifuge,soil and water, occurs ir, the same initialperiod of running as that which is needed inany case for the pore water pressures toapproach initial equilibrium states. Onceequilibrium is approximately achieved themodel test perturbation can begin; forexample it may be the introduction ofcontaminent into a land fill and the slowmovement of a contaminent plume into theqround water. However, In general thechanges of temperature from night to dayduring a long duration rest are moresignificant than init-:i changes duringwarming up.

Acutronic's proposal, page '2, item T11 2,and page 18, item IV 3, refers to airconditioning and to room temperature; itshould explain how the low speed fans,thermostat, motor power relay and automaticcontroller will achieve environmental controlof ambient conditions in the centrifuge pitand around the model. ANS&A has not vet hadthe opportunity for discussion in detail withall potential users of the WES centrifuge andtherefore cannot define precisely whattemperature limits should be requested,however in general when US research workerswork in "air-conditioned" laboratory


conditions they would normally expect fullair conditioning.

111.2,2 Closed circuit television

The CCTV will be mounted in the front shroud;consideration will be needed concerning thelighting arrangements to avoid bounce-back ofreflected light. The CCTV system must becompatible with the proposed computer systemsuch that a future upgrade would allowdigitial image processing.

111.2,5 Centrifuge interface

All computers and all computer controlleditems should be the subject of a specialreview to ensure that hardware and softwareconform to US standards and that all systemsare compatible and maintainable and capableof upgrading in future as required.

1II.2,6 Computer system

This should be selected in consultation withWES to be compatible with similar systems onthe Station. The make of equipment should bespecified.

111.2,7 Software

Acutronic should consult with WES and specifythe language used for code development.

=1i.2,9 Large platform

An optional additional counterweight, and alarger 1.6 m x 1.3 m swinging platform fortests of up to 3 tonnes mass at 200g and 6tonnes at 100g are offered but should not bebought. If the limiting tests on thestandard 350g platform and on the optionaladditional 200g platform are scaled up toprototype parameters, it is clear that theoptional platform is not necessary:

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comparison between standard and optional platforms

Scaled up standard optionalprototype 350g platform 200g platformdimensions (l.3m x 1.3m) (l.6m xl.6m)and masses 2T 4T 3T 6T

at 350g at 150g at 200g at 100g

length (m) 455 195 320 160

breadth (m) 455 195 260 130

area (hundreds 2070 380 830 210of square metres)

mass (megatonnes) 86 14 24 6

The additional 300 mm on the length of the200g platform would only be useful for a longitem of equipment. However, considering forexample a hydraulic tank, it would be betterto make a special item which could perhaps bea swinging tank of over 2m length,customised to the actual needs of the user,rather than a 1.6 m tank made to fit on ararely used 200g platform. Alternativelythere may in future be a special swingingcontainer for earthquake model tests, whichwould be better value than the 200g platform.Hence WES should not buy the 200g platformbut are recommended to divert such resourcesas are available for development ofinstrumentation and equipment to the creationof items for use on the 350g (l."m x 1.3m)platform for which the machine Is nowdesigned, or for the development of special

items designed with specific tests in mind.

1.2 CONTAINMENT STRUCTURE

-he construction of the containment building and thechanges and alterations to the existing office andcontrol building will be the subject of contracts thatare separate from the contract for centrifugemanufacture. ANS&A, and potential users of thefacility, must be involved in detailed discussion and

5


planning of those works before contracts for the worksare placed.

Acutronic Proposal 9530A (February 1991) suggests acontainment building which places the foundation of thecentrifuge on filled ground and moves the building awayfrom the original location shown on WES Drawing No. C-3398-1. From these drawings it appears that thecentreline of the arm is at an elevation of 192.5 ftwhich is the same level as the road surface between thecentrifuge and the Casagrande building. This elevationfor the centrifuge must be changed. A centrifuge of thepower proposed for WES should be in a pit. Theoriginal 200g centrifuges at Nantes is at the samelevel as their office and control building. This schemeis not appropriate for WES now that a 350g centrifugeis proposed.

In the existing terrain at WES beside the office andcontrol building there is a guiley which will minimisethe need for excavation with the containment buildingreturned to its original location. The formation levelfor excavation for the foundation of the cave below thecentrifuge should be no higher than elevation 157 ft.The cut soil will be useful in making safety bermsbeside the building.

There should then be a passenger lift and stairwellfrom the crane access point down to a small door in thewall of the chamber. The air vent passage above thechamber roof will be at right angles to the directionof the crane access way. A separate stairwell willconnect the air vent and passage and the motor room inthe cave below the centrifuge. There will be no needfor large access doors in the wall of the chamber.Neither stairwell shall be open to people during acentrifuge test.

it will be essential for Acutronic to be able to liftheavy objects in the centrifuge chamber, not onlyduring the installation of the centrifuge, but also infuture maintenance and possible centrifuge alterations.It remains to be resolved if this has to involve alarge access door and a roadway at an appropriatelevel, or if it may be achievable by other means.

In some centrifuge model tests it is normal todischarge water from test packages in flight. In sometests a blast may cause ejection of solid material. Insome tests objects may detatch. In the design of the

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containment structure, consideration must be given tocollection of all fluids and solids that aredischarged. The possible use of polystyrene liningblocks on the pit wall should be considered.

1.3 THE CRANE

The crane in the existing office and control buildingmust be examined to see if it is capable of accuratepositioning of models on the centrifuge platform. Withsuch a crane there will be no problem in levelseparation between the access and pit roof level.There can be a low wall or lip, say about 2 ft high,over which the packages can be lifted before beinglowered vertically through the hatch in the chamberroof on to the centrifuge platform. The height of thewall will be dependant on the exact elevation of thecentrifuge.

Although ANS&A does not recommend purchase of theoptional 200g (l.6m x 1.3m) platform offered at presentby Acutronic it is possible that at some future datethe crane will be required to carry loads greater thanthe 4 tonnes permitted on the 350g (l.3m x 1.3m)platform. If it is necessary to replace the crane inorder to have more accurate and careful positioning ofmodels on the centrifuge platform then considerationshould be given to a change of crane to 6 tonnes ratherthan the present (10000 lbs) capacity.

1.4 ALTERATIONS TO THE EXISTING OFFICE AND CONTROL BUILDING

The interior of the existing office and controlbuilding will require changes and additions to

fittings. The padded insulation is soft and will tearand collect dust. There will need to be a suspendedceiling because of dust in model making. ANS&A willreview the use of rooms and space, the positioning of

windows and so on, and will make detailed proposals foralterations.

1.5 PROGRAMME FOR FUTURE ANS&A RESEARCH CONTRACTS

To assist WES during the project ANS&A have proposed aseries of contracts which are linked to different

phases of work. rhese are as follows:

F_°


Phase I In Phase 1 ANS&A has set out detailedproposals for aquisition of an Acutroniccentrifuge by WES.

Completion is achieved with this finalreport.

Phase 2 In the agreed Phase 2 contract ANS&A will setout detailed proposals for aquisition ofcentrifuge instrumentation and equipment.ANS&A will comment on dynamic actuation andthe achievement of capabilities in the areaof blast and earthquakes and on theachievement of other capabilities requiredand identified by WES;

Target completion end December 1991.

Phase 3 In Phase 3 there will be activities by ANS&Afollowing the decision by WES to proceedfurther with the aquisition of an Acutroniccentrifuge. To assist Acutronic in achievingan efficient design process ANS&A will notwait to comment on the evolving calculationsuntil a book full of all calculations iscomplete. ANS&A envisage that their ProjectEngineer in France will continuously reviewsuccessive portions of the detailed designcalculations, month after month, in a manneracceptable to Acutronic, ANS&A and WES. Thisprocess will be initiated during the first ofthe Phase 3 scopes of work, identified as 3A,and will be completed during the secondstage, Phase 3B.

3A Agreed lump sum contract (a) to report on theproposed design and construction of thecontainment structure and on the alterationsof the office and control building, (b) toreview the needs of potential users of thecentrifuge center with a view to identifyingareas which may have an impact on thedetailed design of the center and (c) toinitiate the review of the final detailedcentrifuge design calculations.

Target completion end October 1991.

3B Proposed contract for ANS&A to complete thereview of the Acutronic centrifuge design

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calculations, and to complete the QA and QCprocedures for the centrifuge during thefabrication, installation and commissioningphases.

Completion coincides with Acutroniccompletion of centrifuge commissioning.

Phase 4 In Phase 4 there are activities by ANS&Aadditional to and extending beyond the Phase2 consideration of centrifuge instrumentationand equipment, to assist WES in achievingcentrifuge capabilities. As with Phase 3,Phase 4 will also consist of two scopes ofwork, 4A and 4B.

4A Proposed ANS&A assistance to the WES ProjectManager and Chairman of the WES coordinatingCommittee, specification of equipment,development of management structure,assistance with proposals and marketingactivities. Assistance with projectmanagement and with integration of QA overentire facility.

4B Proposed ANS&A assistance to WES duringperiod of ANS&A custodianship for first andsecond years of operations and commissioningof capabilities on WES centrifuge.

Completion 1 to 2 years after Acutroniccompletion of commissioning.

1.6 COMMISSIONING BY ACUTRONIC

Section 4.5 describes the nature of the commissioningtests that will be required before acceptance of thecentrifuge by WES. These tests will be carried outunder the supervision of ANS&A.

1.7 CUSTODIANSHIP BY ANS&A

For a period following commissioning ANS&A propose tooperate the WES centrifuge on behalf of WES whilsttraining and the development of capabilities isundertaken. This period of custodianship may last for1 to 2 years. During this time new equipment will becommissioned and tests undertaken to establish the new

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facility as a center of excellence in centrifugeresearch. At the end of this period WES will have aunique facility with outstanding capabilities for newadvances in the field of physical modeling.

1.8 M&GUZtT STRUCTURE

The achievement of capabilities will require thedevelopment of an experienced and effective managementstructure in the period between the commissioning ofthe Acutronic centrifuge and the handover to WES.ANS&A expect the process zo start with the selection ofa WES Project Manager.

ANS&A have proposed that a Committee be formed based onthe list of authors of the December 1990 draft WESMiscellaneous Paper "Feasibility Study: WES - acentrifuge test facility", to coordinate theinvolvement of all potential DOD centrifuge users.ANS&A have proposed that Dr Ledbetter be appointedChairman and that ANS&A participate in all meetings(Drs Steedman and/or Schofield). At the first meetingthe Committee should review and revise the list ofinitial tasks proposed by ANS&A in 1989 in theirresponse to the BAA in the light of their own evolvingneeds and Acutronic's revised technical proposal 9530Aof February 1991.

ANS&A propose that Dr Ledbetter combine the roles ofWES Project Manager and Chairman of the Committee. To

fulfill both roles he will need to have time allocatedto the work, and be able to travel both within the USAand abroad when this is essential.

The Committee's work will lead to an improveddefinition of the equipment needed for the initialtasks and of potential funding for instrumentation andequipment. The Committee would create a user group,identifying initial and later users. The Committeewould clarify the needs for training of USAE personnel.

The Committee will discuss the need for earlyexperience with blast loading. ANS&A propose t - -contact is established with Tyndall AFB at an earlydate and that this facility or a similar unit be usedto provide early experience for WES users.

The Committee will consider sources of funding forfuture research and the marketing activities necessary

10


to build up a strong user group.

ANS&A strongly advise WES to designate a mechanical orother engineer as early as possible in the project whowill eventually take responsibility within WES for allmechanical engineering and safety aspects of thecentrifuge facility and its operations.

This person would play an important role in projectmanagement, assisting the WES and ANS&A ProjectManagers, in all phases of the quality assurance.However, if such a person is not in place, ANS&A willcarry out the tasks that such a person would berequired to perform. ANS&A strongly recommend that WESput forward their own engineer by the end of September1991, but if not then ANS&A must carry these projectmanagement responsibilities on behalf of WES as a newactivity within the scope of work for Phase 4A (seesection 1.7).

During the period of custodianship by ANS&A followingcommissioning, the new capabilities will be achievedand research data from the new facility will becomeavailable. The full range and scope of the newcapabilities will not become apparent until experimentsstart to be completed on the new centrifuge duringANS&A's period of custodianship. At this stage it willbecome necessary to define the final managementstructure. The appointment of a WES Director of thefacility and of a WES facility Manager shall not bemade until the end of the period of custodianship byANS&A.

1.9 ANNOUNCEMENT

Following the placing of the next contract withAcutronic it will be appropriate to make anannouncement that WES are initiating the constructionof a major new facility. This centrifuge facility willbe unique in certain respects but there are alreadyother centrifuges under order which will rival it incertain features.

ANS&A advise caution in wording, as follows

WES are to establish a centrifuge model testfacility which will house an Acutronic 684-1centrifuge, to be supplied by Acutronic USA Inc.of 139 Delta Drive, Pittsburgh 15238 PA.

i1

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1.9 (contd.)

This very powerful centrifuge is expected tooperate normally up to 280 gravities with maximumcapacity up to 350 gravities with 2 tonnespayload. Installation and operation of thecentrifuge in a new special building is expectedto be by October 1993.

Capabilities of model testing will be achieved invarious fields, including geotechnics, hydraulics,coastal and environmental and cold regionsengineering. The relevance of centrifuge modeltests to US needs can be judged from considerationof the scale factors in 1/280 scale centrifugemodeling at 280 gravities; the movement of agroundwater contaminent plume in 12 hours in amodel represents the movement of a full-scaleplume in 100 years in the field; the explosion ofa 5 gm charge in a model represents the explosionof 100 tonnes of explosive at full-scale in thefield. Such tests can be made scientifically,economically, quickly and repeatedly, and shouldresult in a greater accuracy and lesser number offield tests.

In the achievement of model test capabilities, WESwill receive assistance from Andrew N Schofield &Associates Limited of Cambridge, England. DrSchofield and his associate Dr R S Steedman areauthorities on centrifuge model testing; theyexpect that a unique range of capabilities willnave been achieved by December 1994.

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2.0 DETAILED SPECIFICATION OF THE CENTRIFUGE

2.1 INTRODUCTION

The objective of providing a system of qualityassurance for the centrifuge is to ensure that the newfacility will be capable of achieving the newcapabilities in physical model testing identified byWES. To achieve a long life the documentation must bestructured and complete, assessed independently asmeeting appropriate standards for a unique and powerfulresearch facility. Two main components provide thebackbone of quality assurance procedures for thecentrifuge itself:

1. The definition of a set of technical and performancespecifications that will serve as a reference framefor the contract, in the discussions with Acutronic,and for commissioning the centrifuge;

2. The definition of a frame-work of procedures forindependent control of the manufacturing and forcommissioning of the machine.

2.2 DEFINITION OF A SET OF TECHNICAL AND PERFORMANCESPECIFICATIONS

Acutronic's proposal 9530 and Technical note 5971 givea detailed presentation of the 684-1 model. Howeverthese documents do not include all the information thatis needed to define exactly WES requirements, but onthe contrary contain information that may change duringthe design phase and which then should not be madecontractual.

Specifications of the facility which can be fixed atthis stage are detailed below together with a set ofcharacteristics that Acutronic should define during thecourse of the design phase.

ANS&A envisages that their Project Engineer in Francewill apply all the lessons that have been learned fromthe design, construction and operation of the Acutronic661, 665 and 680 centrifuges to the process of designof the Acutronic 684 centrifuge. Some of these mattersare detailed in sections 3 and 4 on Quality Assurance.However it must be emphasised at the outset that theANS&A budget does not cover the cost of an independent

13


fully detailed recalculation for the 684 centrifuge.Reliance is placed entirely on Acutronic calculations,and these calculations relate to a 684 centrifugespecification that greatly exceeds the specification ofthe 680 centrifuge. The function of the ANS&A ProjectEngineer in France is to inspect and to review alldocuments, and to interact positively with Acutronic atall stages of design.

It should be noted that in this report the words"swinging platform" refer to the 1.3 m x 1.3 m platformand to its supporting hangers, and are equivalent tothe words "swinging basket" in the Acutronic proposal.

2.2.1 Radius of the centrifuge

Two radii should be specified for operations:

- A "nominal radius" to the centre of mass of apayload of 6m from the axis of rotation atwhich the performance of the centrifuge isdefined;

- A radius of 6.5m to the platform of theswinging basket from the axis of rotation inflight.

2.2.2 centrifugal acceleration

The centrifuge shall generate controlledaccelerations from 10 to 350 gravities ( 1 g9.81 m/s2 ) at 6 m radius.

2.2.3 Payload

The payload is the mass that can be carried on thestandard swinging platform with a centroid at 6 mradius.

The maximum payload depends on the centrifugalacceleration and should be specified as follows:

2000 kg at 350g.

The nature of the increase in allowable load withreduction in acceleration should be defined byAcutronic (it was noted above that Fig. VI oftheir proposal has a change of scale on the g axiswhich is unclear).

14


The specified values of payload will correspond toa uniform distribution of pressure over a circularor rectangular standard footprint on the swinging

platform. The circular footprint will be ofdiameter 1.2 m and the rectangular footprint is to

be 1.3 m x 0.5 m, both located in the centre ofthe platform.

Acutronic will supply charts defining the maximumallowable values for concentrated or otherdistributions of load together with values for the

maximum allowable local pressures on the platform.

2.2.4 Dynamic tests

Since the centrifuge is to be used to model

dynamic problems such as the simulation of strongearthquakes or blast loads, Acutronic will definewhat dynamic loads are acceptable on the platformin terms of amplitude and frequency range for the

three directions (radial, orthoradial and

vertical).

2.2.5 Run-life

The centrifuge will be designed for a minimumrun-life of 10 years.

For fatigue analysis the centrifuge shall beconsidered to be rotating for 500 hours per yearwith the following breakdown of test conditions:

50 % at 100 g30 at 200 g20 % at 350 g

in a typical year the centrifuge will start from

rest and stop from full speed about 1000 times.

2.2.6 Factors of safety

Two situations shall be considered for designpurposes:

- a "serviceability limit state" corresponding to

normal operating conditions but under the

maximum permitted imbalance of thecentrifuge;

- an "ultimate limit state" corresponding to the

15


loss of the whole payload and swingingplatform.

For the serviceability limit state all parts ofthe centrifuge will be designed with a factor ofsafety of 2.7 to the elastic limit. In addition, afactor will be applied to the masses of thedifferent parts of the centrifuge to coveruncertainties associated with the determination of

the actual values. Acutronic will make proposalson this point.

In every conceivable ultimate limit state, thecentrifuge should be brought to a complete stopwithout catastrophic failure of the machine or itssupport. In the selection of appropriate factorsof a safety for the diffe-.ent components (at leasta minimum of 1 to the elastic limit), Acutronicshall take in consideration ductility and fatiguerequirements, providing the necessaryjustification in each case.

2.2.7 Characteristics of the 0 - 350 g swingingplatform

2.2.7.1 Platform

The dimensions of the available area forpackages on the swinging platform are to be:

- width of 1300 mm (horizontal directionperpendicular to the radius);

- length of 1300 mm.

The maximum error in flatness over the platform

will be 0.2 mm, ie. ' 0.1 mm.

The maximum deflection between any two pointsof the loaded area on the platform for all g

levels will be less than 1.0 mm, for auniformly distributed payload over the wholeplatform or over the standard payloadfootprints defined in section 2.2.3 .

The design should allow for easy futureinspection of all welds.

Acutronic will provide threaded holes on theplatform in order to allow fixing of service

16

IK


plates or positioning of equipment in a matrixto be agreed during the final desiqn.

2.2.7.2 Free height

The platform must accommodate test packages1300 mm wide, 1300mm long and at least 1100 mm

high: additional height would be valuable.

2.2.7.3 Lateral supports

The lateral supports or hangers for theplatform should also serve as supports for :

- the hydraulic and electrical lines that runfrom the hinge to the platform and thetest package;

- video CCD cameras.

2.2.7.4 Windshield

The swinging platform should be protected by awindshield comprising the following differentparts:

A front shroud with mountings for a CCDcamera or cameras. With the viewing windowof a package facing forward, to be seen bythe CCD camera, there must be provision thatdirt will not be deposited on the window.

- Lateral doors which can be easily andsecurely installed and which do not restrainthe useful volume on the platform;

- a rear shroud largely open to provide easyaccess to the test package.

2.2.7.5 Maximum friction at the hinge

The swinging platform should oscillate freelyat the end of the rotor arm of the centrifuge.During rotation, friction at the hinge willresult in an angular shift between the actualdirection of the perpendicular to the platformand the resultant of the centrifugalacceleration and earth gravity. Friction shouldbe low enough to limit the angular shift to amaximum of 2', regardless of the acceleration

17

4


and payload.

2.2.8 Vibration of the swinging platform

During rotation the platform should not oscillateor vibrate due to aerodynamic effects or inducedmechanical vibrations. The amplitude of vibrationalong three perpendicular axes should be less than1% of the imposed centrifugal acceleration on theplatform.

2.2.9 Imbalance

The centrifuge should be designed to run with apermanent imbalance of 200,000 N under itsserviceability limit state condition.

Under the ultimate limit state the maximumimbalance will correspond to the loss of a wholepayload and swinginging platform.

2.2.10 Dynamic balancing system

During rotation a dynamic balancing system willpermit slow variations of the moment of inertia ofthe payload to be compensated. In ANS&A's secondinterim report a maximum imbalance compensation of± 1,000,000 N at 200g was specified; inAcutronic's revised Proposal 9530A a maximumimbalance of ± 200,000 N is quoted (withoutidentifying a specific g level). This discrepancywill need to be resolved at an early date duringthe detailed design phase.

2.2.11 Counterweight

The various payloads are balanced by a combinationof fixed and moving elements of counterweights.The selection of masses for the counterweightshould correspond to the different ranges ofoperation of the centrifuge. The presence of thefixed elements of the counterweights cn the rotorshould be automatically detected by the safetymanagement system.

The moving parts of the counterweight should beshiftable manually or by using a small electricmotor placed on the side of the centrifuge axis.

2.2.12 Rotor arm

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The rotor arm, between the central axis and theswinging platform, is covered with shrouds on theupper and lower faces. These shrc'ids should beremovable to give access to the space between thetwo tubes.

The rotor arm is equipped with service channelsthat carry the hydraulic and electrical (power and

low level measurement signals) lines from thepivot to the arm end. Service channels forelectric power supply and measurement signalsshould be well separated. Crosstalk betweensignal and power channels must not be detectable.

The space close to the axis of rotation will bearranged to accommodate the installation of dataacquisition systems and electronic equipment. Thisarea should be defined in more detail indiscussion with Acutronic.

2.2.13 Access on to the centrifuge

The stationary part of the centrifuge and therotor should be equipped in such a way that it iseasy for someone carrying small loads to reach andget on to the pivot area and rotor arm.

2.2.14 Motor drive system

The motor drive system consists of an A.C.brushless variable speed induction motor and agear reducer.

The characteristics or these elements .ind of thecommand system will be selected by Acutronic tomeet the following specification:

i. Tests must be capable of being run at any glevel between 10 and 350g with the maximumpayloads defined above in section .

2. The centrifuge must be capable or zontinuousoperation for periods of at least i month induration;

A g rate of change (up or down) Df .55 g/sfrom log to the maximum centrifugalacceleration is to be provided under the

computer control. Under manual operation this

19


rate may be decreased up to 30%. No criteria isspecified below 10g.

4. The drive system and motor controller must bedemonstrated to be electrically quiet since"the centrifuge testing environment is highlysensitive to electrical noise", Randolph et al.(1991).

5. The drive system must not introduce vibrations

into any part of the centrifuge or the buildingat any stage of operations from rest to maximumacceleration and back to rest. Vibrations atlow speed have been known to cause damage tosensitive models.

2.2.15 Control of the specified acceleration

The difference between the actual acceleration andthe prescribed value should be less than 0.2% ofthe prescribed value or 0.1 rpm, whichever isgreater, the measurements being made at 10 secondcounting intervals. This applies withoutlimitation of the duration of rotation of thecentrifuge.

2.2.16 Command of the centrifuge

The centrifuge must be capable of being controlledeither:

manually (in which case a given rpm value isprescribed by the operator and the centrifugespeed is ramped automatically),

- or under computer control (the operator definesan acceleration profile).

2.2.17 Orientation of the centrifuge at a stop

it should be possible to rotate the centrifugemanually when the motor is at a stop.

2.2.18 Behaviour of the centrifuge during power cutsor surges

-n the case of micro power cuts or power surgesthat do not cause the motor to stop the commandand safety systems must be designed so as not tocause the centrifuge flight to be interrupted.

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2.2.19 Sliprinqs (hydraulic, fibre optic and electric)

The number and and nature of slip rings will bedefined at an early date following agreement withWES on their required capabilities.

2.2.20 Safety

Acutronic will provide safety facilities and asafety management system that will reduce thelikelihood and consequence of any accident. Humansafety and the safety of the facility areconsidered separately below.

2.2.20.1 Safety of persons

Safety systems will be provided to include:

- the prevention of centrifuge start-up untilthe operator has positively checked thatnobody is in the centrifuge chamber and thatthe doors are correctly closed;

- the prevention of access to the centrifugechamber whilst in rotation;

- a signal to the operator that someone isentering the motor chamber or other rooms inthe restricted area.

Acutronic will provide emergency push buttonsand their integration in the safety managementsystem to inhibit operation of the centrifugefrom the centrifuge chamber, the motor pit, thepower control cabinet, the centrifuge controldesk and restricted access areas.

2.2.20.2 Safety of the centrifuge

Safety of the centrifuge itself is primarilyconcerned with the detection of imbalance, theprevention overstressing of the centrifuge, thedetection and management of the centrifugeoperation and environmental conditions.

21


2.2.20.2 (contd.)

1. Detection of imbalance

The imbalance of the centrifuge is to bemeasured continuously. The sensitivity ofthe measuring system should be equal to1/100th of the maximum allowable permanentimbalance. If this maximum value isreached, the centrifuge should beautomatically stopped.

2. Prevention of overstressing of thecentrifuge

Since the maximum payload depends on theacceleration level, the safety managementsystem should prevent the risk ofoverstressing the centrifuge because of anoperator error. Operation ranges will bedefined by the mass of the payload and themass of the fixed counterweights.

The prevention of this risk should becoupled with the automatic detection of thepresence of the adjustable fixed elements ofthe counterweight.

Acutronic will supply a redundant system ofencoders to determine the velocity ofrotation of the centrifuge and to detectoverspeed.

When the manual mode is used, the commandsystem should incorporate devices thatprevent unacceptable changes in operationranges by the centrifuge operator.

3. Monitoring of operating and environmentalconditions

Detectors will be included as part of thesafety management system for monitoring:

- temperature, humidity and smoke in themotor pit, centrifuge chamber, powersupply cabinet and control room inappropriate locations as necessary;

- flows in the lubricatinq loops of the

22


bearings and gear;

- vibration on the centrifuge;

A closed circuit television system with 4video cameras will be installed to surveythe restricted access areas.

All systems will be monitored from theoperator's control desk.

Whenever possible the safety managementsystem will warn the operator when anintermediate value is reached and before thecentrifuge is automatically stopped. Alarmsshould trigger audible and visual signals,and be logged by the operator's computer.

All safety devices should be protectedagainst power cuts and surges and shouldstay operational until the complete stop ofthe centrifuge.

Under all reasonable circumstances access tothe centrifuge chamber should be possible assoon as the centrifuge has stopped.

2.2.21 CONTROL DESK

The command and control desk will include

- the centrifuge commands and controls,

- the computer interface,

- a desk calculator,

- the safety management system, instrumentationand displays,

- a TV rack and TV monitors of the closed circuitsystem,

- meters for counting the number of hours ofrotation of the motor and of the centrifuge,

- display of the acceleration when using thecomputer command mode.

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2.2.22 INTERFACES WITH THE BUILDING

Acutronic will declare whatever data is criticalfor the design and construction of the building,including:

- critical dimensions and tolerances of thecentrifuge chamber and motor pit;

- limiting aerodynamic pressure distribution inthe centrifuge chamber;

- calculated positions and areas of the aperturesfor air conditioning of the centrifuge chamberin order to limit the temperature increase inthe centrifuge chamber;

- maximum forces developed in the foundations ofthe AC motor, the gear reducer, the centrifugeconcrete base and in any other anchoring parts,both for the service and ultimate limit states;

- electrical supply requirements;

- layout of all the conduits and requirements forreduction of electrical noise resulting fromcurrents in all electrical connections betweenthe different areas;

- critical requirements for mechanical access andall procedures and handling requirements forinstallation of the centrifuge and of the motordrive system in the building, and for allfuture maintenance.

2.2.23 MISCELLANEOUS

In the contract to Acutronic tor deivery ct thecentrifuge it will be necessary to specify indetail:

1. The roles of Acutronic USA and AcutronicFrance, and the relationship of the WES ProjectManager and the ANS&A Project Manager to them;

2. The manifest of items to be delivered byAcutronic USA;

3. the list of documents to be supplied byAcutronic USA;

24


4. the extent of the activities of Acutronic USAand Acutronic France on site;

5. the procedures and type of tests necessary forcommissioning and acceptance of the centrifuge(discussed in section 4 of this report).

6. The relationship between the flow of paymentsby WES to Acutronic USA and their performanceor their failure to perform the requirements oftheir contract.

25


3.0 QUALITY ASSURANCE: GENERAL REQUIREMENTs

3.1 INTRODUCTION

A Quality Assurance (QA) Programme which will provideWES with a general framework for formal qualityassurance for the whole centrifuge facility isdiscussed below. The provision of this facility, itsdesign, fabrication and commissioning, together withthe necessary model test equipment and technologytransfer will place severe demands on both client andcontractor. The implementation of this programme willensure that the facility which is purchased will be ofan appropriate quality for WES's requirements, with acarefully documented history and strict operatingprocedures which will provide the basis continued safeoperations into the future.

Specific requirements relating to the centrifuge, thecontainment and laboratory building, and to theequipment and instrumentation follow this section.

The QA Programme detailed below provides an overridingquality plan which allocates responsibilities withrespect to Quality Assurance, ensures that a consistentand reliable documentation of the project is built up,and provides procedures for the implementation of theprogramme with respect to the project. The objectiveis to achieve efficient Project Management and tominimise the risks to all parties which are inherent insuch a large and unique development.

The Quality Assurance Programme is cased on therequirements of British standard BS 750:Part 1:1987i

which is identical to the International Jtandard :SO9001-1987 "Quaiity Systems - Model -or .ualityassurance in design/development, production,installation and servicing" published by theinternational Organisation for Standardisation (ISO).

BS 5750 : Part 1 : 1987,

Qua]. ty Systems, Part I. Specitication fordesign/development, production, installation and security,British Standards institution.

26

.... . .. .


3.2 IMPLEMENTATION

The implementation of the QA Programme will be theresponsibility of ANS&A, acting on behalf of WES.

The company organisation and reporting responsibilitiesfor this project detailed below. The responsibilitiesof individuals with respect to the Quality AssuranceProgramme are defined as follows:

Dr A N Schofield, Managing Director and ANS&AProject Manager, Principal Investigator.

The Managing Director is responsible forestablishing company policy and the QualityAssurance Programme. This includes ensuring theauthority and independence of the QA Manager andmonitoring the adequacy of the QA Programme.

- Dr R S Steedman, Associate Investigator.

Dr Steedman will act as QA Manager for the WESProject both in Europe and in the USA. Theresponsibilities of the QA Manager are:

1. The initiation, development and modification ofpractices affecting quality;

2. Monitoring the compliance of project tasks toQA requirements;

3. Monitoring the implementation and accuracy ofthe QA Programme with periodic review and auditof QA files, records and WES input;

4. Evaluation of nonconformance reports;5. Definition of remedial measures and follow-um

action.

- ~Project Engineers.

ANS&A will appoint Associates to act as ProjectEngineers on the WES project. Theirresponsibilities with respect to the QA Programmeare:

1. Formulation of job tasks and task numbers, suchthat the project is broken down into welldefined elements;

2. Establishment and maintenance of project QAfiles;

3. Investigation, documentation and correction ofconditions of non-compliance to the quality

27


plan;4. Filing, control and distribution of all project

quality related documents;5. Assuring implementation of the Quality

Assurance Programme and procedures.

3.3 PROJECT QA FILE

A project QA file will be established for each project,such as the supply of the centrifuge or for specificprojects concerned with equipment development.

The QA file shall be the focus of all projectdocuments. It may be necessary to file project relatedtechnical documents, calculations or correspondence

files separately for reasons of space and these wouldform an extension to the project QA file.

The establishment and maintenance of the project QA

file is the responsibility of the Project Engineer.

The project QA file shall contain the followinginformation and logs thereof, such that thecompleteness of the QA file can be verified:

- Contents list specifying the location of anyextensions;

- Incoming correspondence and other technical input;- Calculations;- Outgoing correspondence;- Reports;

- Name, specimen signature, specimen initials andstart date for all project personnel;

- Documentation of Quality Assurance audits for theproject;

- Any other project specific quality relateddocuments.

3.4 DOCUMENT CONTROL

The logs for incoming and outgoing drawings,calculations, specifications and reports shall containthe document number, title, revision and date. Allquality related project correspondence shall havedocument control numbers written or stamped on thefront sheet with the receipt date for incomingcorrespondence and the transmitted date for outgoingcorrespondence. Correspondence shall be logged in or

28


out as applicable. Superseded documents shall beclearly marked "SUPERCEDED" and all project personnelusing such documents shall be provided with a copy ofthe updated documents.

3.5 CALCULATIONS

One or more Project Engineers are responsible forassuring that the preparation, review, and approval ofcalculations is in accordance with the qualityprocedures. Calculations shall be checked and approvedby authorised engineers who did not originate the workfor accuracy and adequacy.

All calculations shall be performed, signed and datedby the originator. Calculations shall be approved bydirect checking, and the approver shall also sign anddate the calculations. The calculations are notconsidered final until a unique calculation number isassigned. Approved and numbered calculations shallbecome part of the project files. Computer orspreadsheet runs shall be supported by an explanatorycalculation sheet and approved as above.

3.6 REPORTS

The preparation, review, approval and revision ofreports shall be in accordance with the qualityprocedures.

Reports prepared shall be subject to independent reviewand approval by the ANS&A and WES Project Manaqers.

Each report shall carry a unique number and the levelcf revision shall be clearly stated.

3.7 AUDITS AND NONCONFORMANCES

:he Quality Assurance Manager shall be responsible forperforming internal audits. The purpose of an internalaudit is to ensure that the quality requirements of theproject are properly implemented and to determine theireffectiveness.

A schedule of audits shall be maintained in a log.Requirements for corrective action shall be detailed inan audit report together with a schedule for

29


implementation. Audit reports shall be maintained as

part of the project QA file.

3.8 DOCUMENTATION

Standard forms shall be used to log quality relateddocumentation on each project.

Document control numbers shall be assigned as follows:

Incoming correspondence shall be identified using theproject number, the letter I and the number of thecorrespondence. For example, the first incomingcorrespondence will be assigned the control number,

#-I-001, where * is the Project Number.

Technical input shall be logged using the ProjectNumber, the letter D and the number of the document.Hence the first technical input will be assigned the

control number, 4-D-001, where # is the Project Number.

Outgoing correspondence shall be logged using a similarcontrol number but using the letter C. Outgoingreports shall be logged using the letter R. Internalinspection or Site reports shall be logged using theletter S. Calculations shall be assigned a unique fourletter code followed by a number. Computer orspreadsheet runs will be assigned the code and numbercorresponding to their explanatory calculation sheetfollowed by a final number identifying the run. Forexample, a calculation relating to the centrifuge boommight be identified as, TUBE-OI. A spreadsheet runbased on the same calculation would be identified * s,TUBE-OI-01.

Each page within a document or repcrt should ;-euniquely identified such that the completeness of --hedocument can be checked.

3.9 APPLICATION OF PROCEDURES

Within the framework of the QA Programme procedureshave been developed to meet the specific needs of WESfor the supply of the centrifuge and for other projectsbased on the development of equipment.

Section 2.0 discussed the performance specification for

30


the centrifuge; this can be seen as one aspect of theformal QA requirements for the facility. Section 4.0describes the centrifuge specific procedures forindependent control of manufacturing and commissioningwhich it would not be appropriate to include with thesegeneral requirements.

However, it should be noted that the availabledocumentation for the 684-1 centrifuge is based onpre-design calculations made by Acutronic. It is to beexpected that the detailed design of the facility willintroduce changes to the specification. The objectiveof the QA procedures is to minimise the influences ofsuch changes on the centrifuge performance required forWES.

The design, fabrication and commissioning of thecentrifuge shall be approved by ANS&A on behalf of WESunder the procedures specified in Section 4.0 . Theformal structure of documentation and approval(described below) is based on the QA Programme outlinedabove.

Periodic review of adherence to these procedures, andinternal QA audits, will be performed by the Projectand QA Managers.

Development of equipment by Acutronic or othercontractors will be subject to the same QA Programme.Separate projects will be identified and a ProjectEngineer assigned to oversee the design, fabricationand commissioning of the equipment. A separate QA filewill be maintained for each project detailing thequality related documents.

The QA Programme described above, together with thespecific procedures for the centrifuge projectdescribed in Section 4.0 will ensure that the design,fabrication and commissioning of the centrifuge andother equipment can be adequately demonstrated and thatdecisions taken on behalf of WES relatina to thecentrifuge will be adequately recorded. The objectiveof the QA Programme is to achieve efficient projectmanagement with provision for external inspection, andto minimise the risk of non-acceptance of the facility.The QA Programme is therefore of vital interest to theclient, the consultant and the contractor.

31

V


4.0 QUALITY ASSURANCE PROCEDURES FOR THE CENTRIFUGE

4.1 BACXGROUND

It is the intention of ANS&A that the ANS&A ProjectEngineer in France will achieve as close collaborationbetween ANS&A (acting on behalf of WES) and AcutronicFrance (acting on behalf of Acutronic USA) as wasachieved in the creation of the original LCPC Acutronic680 Centrifuge.

The design of the LCPC 680 centrifuge was the result ofa very close collaboration between Acutronic and LCPC,and the final machine incorporates ideas and conceptsfrom both parties. This collaboration was concluded tohave been beneficial to both client and contractorsince, firstly, the resulting 680 model met all LCPC'srequirements; secondly, comments made during the designphase could be incorporated in a structured mannerdespite not being detailed in the initial contract; andthirdly, it reduced the possibility of litigation.

There are significant differences in the currentproposal for the supply of a centrifuge to WES ascompared to the situation at Nantes. A prototype is notbeing defined from scratch but an existing detailedpreliminary design is being finalised and optimisedusing concepts that have been validated by experience.However there are a number of reasons why it is stillvital to establish a close interaction with Acutronicfrom the very beginning of the design phase:

1. The 684-1 model represents a significant increase incapacity and performance as compared to the 680machine. As it has been seen from the assessment ofAcutronic's proposal there are certains coints forwhich further modifications are necessary.

2. Certain important aspects such the final design ofthe 350 g swinging platform will need to bediscussed again, and the design will need to takeinto account the way this will be used and howmodels will be prepared. Acutronic has no specificexpertise about geotechica model testing.

3. The efficiency of the centrifuge will be dependentin the integration of the needs for instrumentationand anciliary equipment in the design of themachine. From LCPC's experience it appears also that

32


significant savings and better arrangements wouldhave been obtained if equipment could have beendetailed and incorporated during design instead ofat the late stage of installation on site.

The definition of a frame-work for the QualityAssurance procedures for WES will therefore be based ondiscussion in the following sections of:

- the follow-up for the LCPC machine during the designphase and fabrication;

- a follow-up organization adapted to the context ofthe WES machine,

- the procedures of quality assurance to be followedby ACUTRONIC,

- the tests and verifications to be performed forcommissioning the centrifuge.

4.2 DESIGN AND FABRICATION OF THE LCPC CENTRIFUGE

4.2.1 Design phase

LCPC and Acutronic had regular meetings (minimumof I per month) to discuss the progress of thedesign and to make decisions. Acutronic was askedto pass on details of computations and drawings toLCPC.

For certain important questions such as the stressanalysis of the platform and the lateral supportsor the modal analysis of the centrifuge, LCPC madeindependent finite element calculations to improveand check the design, but the responsibility forthe design calculations rested with Acutronic.These checks were used to confirm the correctnessof Acutronic's analyses.

At the end of the design phase a complete file wassubmitted to LCPC for approbation, beforeauthorization was given to start fabrication. Thisincluded a description of the fabrication andcontrol procedures planned by Acutronic.

4.2.2 Fabrication phase

Regular progress meetings also took placethroughout the fabrication phase.

33

L


Acutronic was required to obtain approval fromLCPC for the use of all subcontractors.

A representative from LCPC made visits to thesubcontractors to inspect the manufacturingprocess, and was present during the commissioningby Acutronic of the different component parts.

LCPC expected to be informed directly and as earlyas possible about the progress of themanufacturing and about any problems that couldaffect the programme.

Only standard approved materials were acceptableand all material deliveries had to be accompaniedby the appropriate certificates of °-onformity. Insome cases, tests were requested of . -u7ronic toconfirm the elastic limit or the weldability.

For all welding work, LCPC required that thequalifications of the subcontractors' workers andtheir welding procedures be attested by the FrenchWelding Institute, all welds be checked.

For all components, LCPC was informed of theprocedures of fabrication and control thatAcutronic intended to prescribe to itssubcontractors, as part of Acutronic's internalQuality Assurance system. A draft was preparedand discussed with LCPC at the completion of thedesign phase, following which the final procedureswere set up with the subcontractors. Thisprocedure allowed a series of reports to beprepared for LCPC detailing the complete historyof all component parts.

4.3 PROCEDURES FOR THE DESIGN AND FABRICATION PHASES FORTHE WES CENTRIFUGE

The conditions for creation of the centrifuge for WESare slightly different in so much as the 684-1centrifuge is already generally defined, based to aconsiderable extent on the earlier 680 model. Howeverwhilst the LCPC centrifuge is a 200g facility, the WES684-1 will be designed for maximum operation at up to350g. Consequently it will be necessary, as with LCPC,to carry out an intensive independent oversight of thedesign, fabrication and commissioning stages to ensureas far as possible that a facility is delivered which

34

ANS&A Report 26-)l-R-001

4.3 (contd.)

can meet WES's requirements.

The following procedures will be adopted:

- regular meetings (at least 1 per month) will be heldwith Acutronic during which progress of the workwill be certified and adherance to the programmediscussed. The meetings will provide an opportunityfor technical questions to be addressed and fordifficulties to be resolved. Problems of theinterface between the centrifuge, the civilengineering work and instrumentation or testingequipment will be discussed.

- visits to subcontractors will be made as required,including specifically attendance duringcommissioning by Acutronic of important components.

ANS&A strongly recommend that a WES appointedmechanical engineer is involved in this procedure, andthat WES engineers should participate in meetings inFrance and Cambridge during the design and fabricationstages.

During this phase Acutronic will be responsible for:

- communicating to ANS.&A the necessary informationabout the design and fabrication;

- informing ANS&A of the subcontractors and enablingANS&A to gain access to the subcontractors' sites;

ANS&A reserve the right to request that additionalquality control tests be carried out.

The design review will involve close collaboration andregular meetings between ANS&A and Acutronic at whichcalculations will be presented and discussed. Analyseswhich are regarded as inadequate will be required to bereworked for presentation at a future meeting. In thismanner it is anticipated that the flow of Acutronicwork should not be interrupted for any significantperiod at the completion of the design stage as ANS&Awill already be quite familiar with the record ofcalculations which have been performed for the newcentrifuge.

35


The fabrication phase will end following the completeassembly and integration of the centrifuge in Franceand on shipping to WES.

Progress meetings and special meetings will bedocumented by brief written reports from ANS&A to WES.A final report will be prepared by ANS&A at the end ofthe fabrication phase to provide a commentary on theAcutronic documentation concerning design andfabrication.

As the contract for the purchase of the centrifuge hasbeen placed directly with Acutronic, it will beadvisable for WES engineers to be present at thefactory acceptance test at the end of integration andclearly oversee acceptance at the WES facility at thetime of installation and commissioning. ANS&A willprovide support for WES for these activities during thecommissioning phase at WES and for a period following.

4.4 REQUIREMENTS FOR ACUTRONIC

The contract with Acutronic should include in anappendix details of the system of quality assurancethat Acutronic will apply. This should in particularidentify all the controls that are to be carried out byAcutronic.

In summary, certain requirements can be clearlyidentified (the number of copies of documentation willbe determined at an early date in agreement with WES):

I. All materials will meet appropriate standards. Alldeliveries of materials must be accompanied by theappropriate certificates of conformity;

2. For welding work, the subcontractors' workers andprocedures will meet that appropriate standards ofthe Institut Frangais de Soudure (French WeldingInstitute);

3. All welds will be checked;

4. Acutronic will inform ANS&A of the commissioning ofthe different elements produced by itssubcontractors;

5. Acutronic will provide, with the centrifuge, filescontaining all information related to the procedures

36 1


of control and fabrication of each component part;

6. Acutronic will provide on a monthly basis in awritten form an updated detailed schedule coveringthe design, fabrication and installation phases;

7. Acutronic will supply complete sets of generaldrawings with the nomenclature of all parts at theend of the design phase together with a technicalreport including calculations.

8. The final documentation will be supplied byAcutronic after commissioning of the centrifuge;these documents will include all the modificationsmade during the installation and commissioningphases, User's guides and maintenance guides for thecentrifuge.

4.5 ACCEPTANCE AND COMMISSIONING TESTS FOR THE WESCENTRIUGE

4.5.1 Static tests

For the LCPC machine a certain number of statictests concerning the stiffness of the arm and theswinging platform were imposed in the contract withAcutronic for the following reasons.

A loading test was performed on the swingingplatform once assembled (but before its installationon the site) in order to check that its stiffnessmet the stated deflection criteria. The purpose ofthe test was to check that the numerical analysis ofthe swing gave correct estimates of the strains anddeflections.

This was considered necessary because cr the complex3-D structure of the platform and the act that thedeflection of the platform was to a large extent afunction of the compliance of the lateral supports.

On the LCPC machine the platform is supported at 3points on each side; there were uncertaintiesassociated with the actual behaviour ot the linksbetween the platform and the lateral supports, andconcern that the corresponding analyticalassumptions would have a significant intluence onthe deflections since the structure was hyperstatic.

37


Prior to commissioning the platform could noteconomically be submitted to loads as high as duringrotation with the maximum payload, but this was notnecessary as it was considered adequate for the LCPCcentrifuge to limit the checking to the elasticplatform stiffness.

The tests performed on the LCPC platform in Paris

showed than the predictions with the finite elementmodel were in very good agreement with theexperimental results both for deflections andstrains, and that the platform as designed wouldmeet the technical specifications on elasticdeflections.

This experience is encouraging but noting that,although simpler in form, the platform for the WEScentrifuge will be required to operate at 350g itwill be necessary to confirm computationalpredictions of the platform stiffness with a statictest. These tests will be ordered and paid for byAcutronic, and carried out to a procedure proposedby Acutronic and agreed by ANS&A.

The centrifuge is to be completely integrated inFrance before it is shipped to WES.

4.5.2 Commissioning tests

Commissioning tests will be required under thecontract to be carried out at the WES facility onceAcutronic have declared that the centrifuge is readyfor operation. The tests are designed to check thatthe centrifuge perfo-rance meets the specificationlaid down for in the contract:

The tests will include:

i. Operation from 10 to 350 g in 10 q steps with themaximum authorized payload. For each step thecentrifugal acceleration will be maintainedconstant for 10 minutes;

2. operation from 0 to 100, 150, 200 and 350g withthe maximum payload, at the maximum rate ofvariation of g;

3. A check of the imbalance measurement system withknown masses placed on the platform up to themaximum permitted permanent imbalance. This

38


includes determination of accuracy and linearity;

4. A check of the behaviour of the automatic in-flight balancing system up to its maximumcapacity;

5. Two tests of endurance of 48 hours each will bemade, with the appropriate maximum payload on theswinging platform at 200 g and at 350 g, and withdetailed measurements of temperatures, stresses,vibrations and all other relevant parameters;

6. A test will be required at at least 1og todemonstrate that the angular shift between theperpendicular to the platform of the swingingplatform and the resultant of the centrifugalacceleration and the direction of earth's gravityis less than 2° .

7. Tests will be made to identify the tirst modesand frequencies of vibration -f th- centrifuge inflight;

For all these tests, Acutronic will:

- place strain gauges on the rotor, and on theswinging platform, at locations agreed upon withANS&A;

- provide all the necessary instrumentation tomeasure and record the following parameters:

a. acceleration as function of time;b. strains on the centrifuge;c. vibrations on the base of the centrifuge, and

in the swinging platform;d. power consumption of the motor;e. temperature changes in the motor drive system;f. temperature level in the centriruqe room as

compared to the ambient value;

WES will provide the payloads necessary -or thecommissioning tests at WES.

The satisfactory operation of all accessories willbe demonstrated. The safety management system willbe will be shown to be fully operational. Power cutswill be simulated during rotation.

39

I


5.0 INTEGRATION OF QUALITY ASSURANCE OVER THE CENTRIFUGE,BUILDINGS, INSTRUMENTATION AND EQUIPMENT

5.1 INTRODUCTION

Development of the full range of capabilities incentrifuge modeling at WES will require carefulconsideration of the interaction between thecentrifuge, the containment structure and thelaboratory building. For example, future developmentof a capability to run substantial water flows througha model would be inhibited if adequate provision wasnot made at the design stage for water drainage fromthe centrifuge chamber.

Acutronic's Proposal 9530A shows the centrifuge locatedin a containment structure adjacent to the office andcontrol building. This containment structure will needto meet design criteria associated with a limit state

event such as the loss of the swinging platform and itspayload at 350g. In its detailed design it will needto provide adequate anchorage, even under thesestringent conditions, to ensure the centrifuge does notbecome disconnected from its foundation.

5.2 QUALITY ASSURANCE AND PROJECT MANAGEMENT

During ANS&A's Phase 1 activities attention wasfocussed on the outline design of the centrifuge. Oncethe detailed design phase has begun there will be aseries of decisions that need to be taken quite rapidlyas questions on the specification of the centrifuge and

its associated equipment arise.

These decisions will not be taken in isolation but willhave consequences for the containment and laboratorybuilding. Similarly, decisions concerning thecontainment and laboratory building will have aninfluence on the development of capabilities.

close management of these different activities will benecessary to ensure that, for example, calculationscarried out to meet Quality Assurance procedures forthe centrifuge, its equipment and instrumentation are

integrated with the design approach for the containmentstructure.

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5.3 PROCEDURBS

ANS&A will be responsible for carrying out the Quality

Assurance procedures for the centrifuge and for itemsof equipment and instrumentation. The informationarising from this process will become a part of thesafety information of the facility where it will beintegrated with further information on the containmentand laboratory building which will arise during thedesign and construction phases.

ANS&A is therefore well placed to assist WES with thecoordination and management of the overall project.The advantages of this approach are that prior to theappointment by WES of a mechanical or other engineer(who will untimately take responsibility within WES forall mechanical engineering and safety aspects of thecentrifuge facility and its operations) expert advicewill be on hand concerning the integration of thecentrifuge and the remainder of the facility.Information which will ultimately form part of thesafety information for the facility will need to beidentified and approved within the Quality Assurancesystem. This would be achieved most efficiently by thedevelopment of a single QA system.

Following commissioning of the centrifuge by Acutronic,

ANS&A will work with WES (during a period ofcustodianship) to achieve the outstanding capabilitiesplanned for the facility. Close involvement by ANS&Aduring the design and construction of the facility aswell as in the management of all early operations ofthe centrifuge, its instrumentation and equipment willgreatly racilitate that task. ANS&A will Ie responsiblefor the integration of the facility safety information.

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6.0 QUALITY ASSURANCE PROCEDURES FOR INSTRUMENTATION ANDEQUIPMENT

6.1 INTRODUCTION

Quality Assurance is as necessary for all items ofcentrifuge equipment and instrumentation as it is forthe centrifuge facility itself. New equipment,introduced to the facility, constitutes a change andcreates an increased risk of an accident. Themanagement of the introduction of new equipment orinstrumentation must therefore be rigorous, based onestablished procedures.

In section 3.0 of this report a specification for thegeneral QA requirements was laid down. This provided aframework of procedures for the management of changewithin the facility, applying equally to the centrifugeand to the introduction of any new equipment.

This section provides an interpretation of theseprocedures as they are applied to equipment andinstrumentation and gives some explanation of thebackground to the required calculation procedures.

6.2 FUNDAMENTALS

All equipment or instrumentation for use in acentrifuge facility will have an intended function andits designer will have had to consider the mechanicswhich underly that function. For example, in the caseof the centrifuge, the physics which lies behind theaccelerations acting on the rotating boom are wellunderstood. However, in the case of an instrument suchas a cone penetrometer, or in the case of an item ofequipment such as a downward hydraulic gradientconsolidometer these principles are not so wellestablished and careful consideration is needed beforesuch items of equipment can oe designed ndcommissioned.

-he principles of a particular class of centrifuoemodel test are usually explained in the theses cfresearch students or in the proceedings of specialtyconferences 'r Ln specialty journals; in all theseexamples there is public debate and peer review.However, with the diverse, and in some cases possiblyclassified, range of capabilities that are expected to

42

ANS&A Report 26-01-R-u01

be developed at WES these opportunities to scrutinisethe theory behind equipment development may be lacking.For this reason it is particularly important toconstruct and enforce a rigorous and formal assessmentof the function and performance of equipment proposedfor use on the centrifuge facility.

For example, in cases such as those identified above,it will be necessary to generate a statement of theprinciples underlying an item of equipment in a waythat is intelligible both to the engineers andscientists who are intending to use that equipment andto the engineers and operators who are responsible forthe safe operation of the centrifuge. In some cases itmay be necessary for a special study to be made withexperiments and calculations to prove that principlesthat are stated will apply to the item underconsideration.

6.3 REQUIREMENTS OF EQUIPMENT QA

Quality Assurance procedures applied to equipment andinstrumentation will provide a structured dpproach totheir safe management and utilisation. The use of a QAproject file for each item of equipment orinstrumentation will address five major requirements.These are:

1. To provide a statement of purpose for theequipment or instrumentation;

To provide a statement of the mechanics andphysics that underly that purpose;

3. Tc provide approved calculations or demonstrationsof the strength or power and performance of theequipment;

4. To record the manufacture, commissioning,utilisation and modification of the equipment;

5. To record the performance and maintenance of theequipment.

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6.4 CALCULATIONS FOR SAFETY OF EQUIPMENT

Section 7.4.3 describes in detail the nature of thestress checking calculations required for equipment todemonstrate its safety in centrifuge flight. Thecalculations which are required for QA purposes,concerned primarily with safety are thus based as faras possible on full plastic stress redistribution.Where an item is made of ductile plastic material itsstrength is therefore determined by a calculation ofupper and lower bounds to plastic collapse loads.

Where an item is made of brittle material a calculationof maximum stress and of risk of failure is required.A calculation of stiffness involves knowledge ofelastic properties of the materials from which the itemis made. These calculations can be verified by physicaltests of deflections under load. However it isimportant to state that if in fact a measureddeflection, for example of a icaded platform, agreeswith an elastic finite element calculation, this doesnot prove that the item is safe. There miay be a stressconcentration that will in time initiate cracking, butdoes not affect deflections.

The uncertainty surrounding stress concentrations inbrittle materials is a further reason why theconsequences of failure of such items needs to becarefully defined. In particular it must beestablished that failure of a brittle item will notlead to consequential failure of other items.

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ANS&A Report Z6-01-R-001

7.0 SAFETY OF OPERATIONS

7.1 INTRODUCTION

In 1980 Professor Schofield delivered the RankineLecture to the British Geotechnical Society in which hedescribed the operations of the Cambridge GeotechnicalCentrifuge Centre I . The Appendix to the Rankine

Lecture presented in detail the requirementsestablished at Cambridge University for the safeoperation of the beam centrifuge facility.

The design, fabrication, installation, commissioningand operation of a centrifuge and its associatedequipment and instrumentation represents a processwhich is vulnerable to catastrophic accident. Therehave been several examples of centrifuge accidents inrecent years, such as at the Sandia Laboratory and atNASA AMES. It is significant to note that both of these

involved large centrifuges at US lovernment

laboratories. Both of these accidents were avoidableand it is therefore essential that the new WEScentrifuge facility is subject to a management systemwhich establishes an effective safety regime for all

operations.

In this report a distinction is drawn between general

requirements for safe work practices within a

laboratory and requirements which are specific to the

centrifuge facility. For example within the new office

and control building the power supplies, cranes and

other mechanical and electrical equipment will all pose

hazards in a general sense to workers and to visitors.

Clearly WES will require the new laboratory' to conform

to its own safety regulations and to any applicanle

federal state or local regulations.

This report will concern itself with management safety

systems which relate to the centrifuge rac1lity and its

cperation. The approach adopted here is to identify

separately the questions of management r hanae,

normal operating procedures and training.

Schofield, A.N. (1980),

Cambridge Geotechnical Centrifuge Operations, ceotechnique

30, No. 3, 227-268.

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7.2 SAFETY INFORMATION

7.2.1 General

Within the centrifuge facility there will be arange of hazards from equipment and materials.For example there will be hazards to safety fromchemical contamination, dust and explosives. Adocumented compilation of safety informationshould be developed and maintained for thefacility describing the hazards presented by allmaterials and equipment. This would includetoxicity information, physical properties,corrosivity data and so on. The safetyinformation should also include information onmechanical design of equipment.

7.2.2 Mechanical Design Information

All systems of equipment, such as the centrifugeand custom built model test equipment, should bedocumented and design details maintained as pastof the facility safety information. Inrormationon the centrifuge would include design drawingsand calculations, material certificates,fabrication records and safety information onsystems for shutdown and inter-lock. Informationon off-the-shelf items such as pumps or craneswould include the manufacturer's specificationsand instruction manuals.

7.3 HAZARDS ANALYSIS (HAZAN)

Prior to first start-up of the centrifuge i HazarasAnalysis (HAZAN) should be performed for the facilitywith the object of minimising the likelihood .naconsequences of an accident.

The HAZAN should consider accident scenarios and assesszheir likelihood and conseauences. Changes wnich couldreduce these risks would be identified. As thecentrifuge will be a new facility particular attentionshould be paiz to the design process and to any changesin the design team or in the design which may have hadanforeseen consequences.

The HAZAN should be performed by a team knowledgeablein engineering, centrifuge modelling, storage and useof explosive and toxic materials, mechanical design and

46


operations. At least one member should be experiencedin HAZAN techniques, and at least one should not have

participated in the design process.

A written report would present the team's findings andrecommendations which should be implemented by the

facility management team. Depending on the changes intechnology or use of the facility the HAZAN should be

reviewed at intervals not exceeding three years, but

more frequently if appropriate.

7.4 MANAGEMENT OF CHANGE

7.4.1 General

Accidents are frequently caused by change and themanagement of change is therefore a critical partof the safety process. Thus the start-up of thefacility itself, the proof testing of newequipment, the arrival of a party of visitors areall examples of change which create an increasedrisk of accident. Management of change coversthree broad topics: facility management, equipmentqualification and safety checks, both before aflight and after any changes that may have beeninduced by events occurring in flight.

7.4.2 Facility management

In the Appendix to the Rankine Lecture amanagement structure comprising a Director,authorised engineers, centrifuge operators andresearch workers was defined as applicable to theCambridge beam centrifuge facility. :n recentyears the increased workload and :ompiexity ofmodel tests in Cambridge has led to i furtherposition of Beam Manager who takes day-to-dayresponsibility for the safety of the facility onbehalf of the Director.

At the WES facility it is anticipated that asimilar group of 'resident' experienced workersand 'temporary' visiting workers will evolve overlime. The large size of the facilit- mnd cf theiodel test equipment will also lead to operationswhich are similar in style to those at Cambridge.A similar management structure to Cambridge istherefore proposed for WES, with the followingduties and responsibilities. While the centrifuge

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L .m , lmmmmm ~mmmmmam mmmm m~m


7.4.2 (contd.)

is under the custody of ANS&A the functions of theDirector, Centrifuge Manager and CentrifugeEngineers, will be discharged by ANS&A.

Director The Director of the WES CentrifugeCenter will retain overallresponsibility for the facility and itsoperations, including the authorisationof centrifuge engineers and modelers.

Manager The facility Manager of the WESCentrifuge Center will be responsiblefor day to day administration and safetyof operations, including the testprogramme.

Engineers Engineers employed by WES who havesufficient experience of centrifugemodel testing to give engineeringapproval to the tests cf others, totrain other users or operators, tooperate the centrifuge themselves or toact as centrifuge modelers themselves.The approval of a pre-flight safetycheck will only be made by an authorisedcentrifuge engineer who is not also thecentrifuge modeler.

Operators Engineers or technicians employed by WESwho have sufficient experience ofcentrifuge operations zo advise andassist other authorised users, to verifytest documents, to mount packages, tostart the centrifuge and to undertakeactivities as directed by an authorisedcentrifuge modeler within an agreedprogramme.

Modelers Research workers, engineers or visitorswith sufficient experience of theoperation of the centrifuge to proposeand undertake programmes of approvedmodel tests. It is the responsibilityof the centrifuge modeler to prepare,and to gain authorisation for, a pre-flight safety check.

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L.


The wide range of capabilities available on thecentrifuge will mean that users of the facilityare changing frequently. The list of authorisedengineers, operators and modelers will onlyinclude those with current experience and with aneed for authorisation; authorisation will only be

given by the Director.

The pre-flight safety check, described in Section7.4.4, is a critical aspect of the management of

change. Its authorisation by the facilitymanagement will permit the initiation of a model

test series on the centrifuge.

7.4.3 Equipment qualification

The initial or proof test flight of new equipmentis one of the most severe aspects of change thatcan endanger the facility. The qualification ofnew or modified equipment prior to use is

therefore of paramount importance.

To obtain written approval from an authorisedcentrifuge engineer for equipment to be used on

the centrifuge a stressing check for the equipmentmust be carried out.

7.4.3.1 Stress checks for centrifuge equipment

Self-weight loading under high gravities iscalculated on the basis either of theacceleration of each mass at its actual radiusor on the basis of all masses at a nominal

radius of 6 m for the Acutronic 684-1centrifuge.

Calculations will assume that all containersare filled with saturated soil to their maximumworking level and that this soil may becomefluidised and apply pressures equivalent to a

fluid of density 2100 kg/m3 .

Fluid reservoirs or supply lines should beassumed to be filled either back to the rotoraxis and above or to their vent levels if theyare vented into the chamber.

In the Rankine Lecture the 'first flight' of an

item of equipment was described as a prooftest. As a proof test constitutes the

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7.4.3.1 (contd.)

deliberate introduction of change theauthorisation and execution of a proof testflight was defined rigorously. For the WESfacility the concept of a proof test isextended to cover all centrifuge flights thataccelerate any exposed equipment to within 20%of its maximum past g level. This class of testis called a gmax test and operating proceduresfor these tests are defined in Section7.4.3.2

Centrifuge flights which accelerate equipmentto 80% of its past maximum g level or less areclassified as gnorm tests and are subject tothe normal operating procedures described inSection 7.5 .

This differentiation of higher/lower riskflights is based on safe working practiceswhich have evolved at Cambridge and at othermajor centrifuge centres. At these facilitiesexperience has led to a policy of testingmodels at the lowest practical g level based onconsiderations of model size. It has beenfound from experience that within 20% of theproof test acceleration operator stress risesrapidly and the concentration of the modelershifts from concern over the quality of themodel under test to concern over the structuralintegrity of facility.

In general, then, the maximum q level forstress checking and equipment design will be1.25 times the planned test g level. Tn

circumstances where it is absolutely necessaryto use the centrifuge facility or its equipmentnear to their maximum design capacity tneregulations relating to gmax tests ;ill beadopted and the maximum g level for stresschecking will correspond to the test g level.

Following the guidance above on self-weightloading, equipment design will be approved onthe basis of calculations showing full plasticstress redistribution at the maximum design glevel. Elastic calculations will providevaluable information on stiffness and

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7.4.3.1 (contd.)

deflections of equipment under high g but willbe regarded as insufficient for theauthorisation of exposed equipment for testing.

Standard properties for common materials willbe adopted as follows:mild steel specific gravity 7.83, working

stress 136 MN/m2 ;

dural specific gravity 2.82, workingstress 130 MN/m 2 .

These working stresses, to be used with fullplastic stress redistribution, include a safetyfactor of 2.5 .

Bolts, such as Unbrako type, are consideredductile if not stressed above 30 MN/m 2 intightening up and are designed for 275 MN/m 2

under maximum design g loading. This workingstress includes a safety factor of 3.5 . If

highly torqued, to ensure a seal or frictionjoint, bolts must be discarded after 30 uses.

Where perspex is used for windows it must be

secured by a metal frame with rounded edges notless than 6 mm radius. The perspex must bekept free from scoring. Under maximum design gloading perspex is considered to have aspecific gravity of 1.3 and may reach 7 MN/m2 .This includes a safety factor of 2 and a stressconcentration factor of 2. In other conditionsthe stress concentration factor may rise to 3.5or greater and the working stress will bereduced accordir ly.

The design of windows as flat plates will

follow RoarkI . For example Roark Case 70 givesstresses and deflections in a flat plate undertriangular loading with all edges fixed. For

Young, W.C. (1989),

Roark's formulas for stress and strain, 6th Edition,McGraw-Hill.

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the calculation of deflection perspex will beassumed to have a Young's Modulus of 2.8 GN/m2 .

The objective of the authorising engineer inthis process is the prevention of secondarydamage to the centrifuge facility throughfailure of equipment components. Plasticitycalculations with a requirement for materialductility provide a safe and simple approach tostress checking, allowing for the detection of

overstressing through deflection rather thanthrough brittle fracture.

7.4.3.2 Centrifuge flights under gmax conditions

The term gmax is used to identify centrifugeflights where the structural integrity of thefacility is deliberately put at risk in orderto fully achieve the maximum capabilities ofthe centrifuge and its equipment.

This section describes the management of a gmaxtest. Pre-flight safety checks are consideredin Section 7.4.4

During the gmax flight the centrifuge will beunder the command of the Authorising CentrifugeEngineer, who will be present at all times.The flight will follow a previously agreedprogram of activities as directed by theAuthorised Centrifuge Modeler. The CentrifugeOperator will seek approval from the CentrifugeEngineer for each instruction. Eachinstruction will be noted in the flight log.

At the end of the flight the CentrifugeEngineer will sign the flight log as a true andaccurate record of the flight.

The agreed program of activities may include ahigh g proof test of equipment followed by aslowing of the centrifuge to conduct a modelexperiment. If the centrifuge acceleration isreduced to 80% of the flight maximum or lessand the Authorising Engineer is satisfied as tothe continuing safety of the facility theEngineer may declare that gnorm procedures areto be followed for the remainder of the flight.

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Any change in flight status will be noted inthe flight log.

7.4.4 Pro-flight safety check

Prior to each flight the Centrifuge Operator willcarry out a Safety Check. This will include thefollowing :

7.4.4.1 Inspection of documentation

For gmax flights, the documentation willcomprise

1. A summary sheet giving the total mass of thepackage, the required fixed counterweight,the likely change in balance during theflight, the previous maximum g level, theservices required and the flight programme.

The summary sheet will be signed by theCentrifuge Modeler and by a CentrifugeEngineer.

2. A flight manifest detailing all componentsof the model test equipment, their massesand centroid position. The likely change inbalance during the flight for each componentwill be identified and the overall change inbalance calculated. The manifest should besupported by sketches of the model testequipment clearly indicating the coordinateaxes and direction of travel.

3. Stressing calculations separately approved

by a Centrifuge Engineer qualified in theappropriate field. These calculationsshould be in accordance with therequirements of Section 7.4.3.1 . Stressingcalculations are not required for gnormtests.

7.4.4.2 Loading of equipment

The Centrifuge Operator will be responsible forloading all test equipment onto the centrifugeand for ensuring that it is adequately secured.The weight of the equipment and the fixedcounterweights will be positively checked bythe Operator against the Flight Summary.

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7.4.4.3 Systems safety check

Immediately prior to centrifuge start, the

Centrifuge Operator will evacuate the secure

areas, inspect the model and the centrifuge andcheck that the chamber is clear of looseobjects. The centrifuge operator will note in

the log the details of the flight, includingthe names of those present. The centrifugeoperating systems will be checked and warningsystems initiated in a prescribed sequence.

7.5 NORMAL OPERATING PROCEDURES

Under gnorm conditions the Centrifuge Engineer need notbe present in the control room. However, it isrequired that the Engineer be "on call" at all timesduring a gnorm flight; it is the responsibility of theCentrifuge Modeler to provide the Operator withinformation on the location and availability of theengineer prior to the start of each flight.

During the gnorm flight the Centrifuge Operator willfollow instructions from the Modeler provided thatthese fall within the agreed flight programme andsubject always to being satisfied as to the safety ofthe facility. The Centrifuge Operator may stop thecentrifuge at any time if there is cause to suspect amalfunction or to prevent an accident.

;ith these exceptions, the safety manaqement or a gnormflight will be identical to that of a gmax :light.

7.6 TRAINING

The training of new Modelers, Operators and Engineerswill be carried out under a defined programmeobjectives. The most effective form of training ;w1i

involve periods of formal instruction and periods -n

which trainees work alongside experienced Modelers,Operators or Engineers.

Centrifuge Engineers and Operators will be trained inaccident and emergency procedures.

Authorisation of Centrifuge Modelers, Operators andEngineers is the responsibility of the Director.

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Refresher training will be provided as required, and inparticular on each occasion when a change in operatingprocedures or new equipment is introduced.

Individual training records will be maintained as partof the Safety Information of the facility.

7.7 EMERGENCY RESPONSE AND CONTROL

An emergency which arises during whilst the centrifugeis not operational will be covered by the general

procedures established for the facility.

There are a large number of hazards associated with

equipment and materials, some of which have been

outlined above, which could contribute to an increasedrisk of accident. However human factors, such asfatigue brought about by the stress of long runs, maybe equally serious in threatening the safety of thefacility and must be considered carefully in anyaccident scenario.

A plan to deal with emergencies which occur whilst thecentrifuge is operational will be established and theCentrifuge Operator will be responsible for taking thenecessary actions.

7.8 INVESTIGATION OF ACCIDENTS

All incidents which did result in an accident, or couldreasonably have resulted in an accident, will be

investigated by a team appointed by the Director.

The findings of the investigation will be recorded andkept as part of the Safety Information of the facility.

A system will be established to ensure that agreed-uponactions which arise from the investigation areimplemented.

7.9 AUDIT

An audit of the Safety Management Systems will becarried out periodically to ensure their effectiveoperation. The interval between audits should notexceed three years. The Audit team will be appointed by

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the Director and their report will be kept as part of

the Safety Information of the facility. A system willbe established to ensure that agreed-upon actions thatarise from the audit are implemented.

7.10 DISCLOSURE OF INFORMATION REGARDING SAFETY

The intention of WES to create a world class facility,and to attract internationally distinguished visitorsin many fields of activity to WES, may lead to aconflict of interest. On the one hand generally itwill be of advantage to WES to receive expert commentand advice and therefore to disclose details ofcentrifuge model test operations to visitors. On theother hand in particular instances it will be in thenational interest of the USA or in the local interestof WES not to discuss details of model test operationswith visitors.

In all cases there must be full disclosure of alloperations to one or more members of the WES SafetyAudit team: in particular all blast, shock or otherserious loading or toxic contamination must be keptunder review by the Audit team and must be fullydocumented. In any case, where an item of equipmentthat is made available to a visiting centrifuge modelerhas been subject to blast, shock or other seriousloading or toxic contamination in the past, there mustbe a disclosure to the visitor of any matter which may4eopardise the visitor's project or themselves.

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DTI 26-01-R-001 SAFETY FACTOR ANALYSIS FOR CENTRIFUGE SYSTEMS FINAL TECHNICAL REPORT by A N...

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