STUDIES OF BRITTLE FRACTURE· PROPAGATION IN SIX FOOT … · Complete Fracture Test --A test in...

$: STUDIES OF BRITTLE FRACTURE· PROPAGATION IN SIX FOOT … · Complete Fracture Test --A test in which the fracture propagates across the entire plate 0 Str~ Test --A test in which$
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.- -', '-~ ~~~ CIVIL ENGINEERING STUDIES STRUCTUrtAL RESEARCH SERIES NO. 136

STUDIES OF BRITTLE FRACTURE· PROPAGATION

IN SIX FOOT WIDE: STRUCTURAL STEEL:, PLATES '.--- .-

By R. LAZAR

W. J. HAll

A TECHNICAL REPORT

for the

SHIP STRUCTURE COMMITIEE

under the

BUREAU OF SHIPS, U. S. NAVY

Contract NObs 65790 Index No. NS-731-034

Subproject SR-13 7

UNIVERSITY OF ILLINOiS

URBANA, ILLINOIS

STUDIES OF BRITTLE FRACTURE PROPAGATION

IN SIX Foor WIDE STRUCTURAL

STEEL PLATES

by

R. Lazar

and

W. J. Hall

A Technical Report

for th~

SHIP STRUCTURE COMMITTEE

under the

BUREAU OF SHIPS~ U. S. NAVY

Contract NObs 65790, Index No. NS-73l-034 Subproject SR-l37

Department of Civil Engineering University of Illinois

June 1957

I I f f ~

( le c .. c C ...

ii

TABLE OF CONTENTS

Page

I. INI'RODUCTION. . . . . · · · . · · · · · 1

l. General. . . . . . . . · · · . 1

2. Object and Scope . · · · · 1

3· Brief Review of Previous Work. 3

4. Acknowledgment . · · · · · 4

5· Nomenclature . .. · · · 5

II. DESCRIPrION OF ~IMENS AND APPARATUS. · · · · 6

6. Specimens and Material Properties. · · · · · · · · · · 6

7· Fracture Initiation. · · · · · 7

8. Cooling Apparatus. · · · · · · · · 10

9· Instrumentation. . · · · · · 10

(a) Sensing Devices. • 10 · · (b) Recording Devices. · · · · · · · · · · .. · 12

(c) Input Circuits · · · · · · · · · · · 14

(d) Measurement Procedure and Calibration. 15

(e) Data Reduction · · · · · · · · · · · .. · 16

10. Test Procedure . . · · · · 16

III. RESULTS AND INTERPRE1:ATION OF TESTS · 18

11. Test Records . · · · · · · . · · · · · 18

12. Striking Tests · · · 20

13· Complete Fracture Tests. 22

(a) Fracture Speed · · · . · 22

rI.

(b)

(c)

(d)

(e)

(:f)

TABLE OF CONTENTS (Conrt.)

Dlf,namic strain Measurements.

Crack Path and Texture .•

Semi-Killed Steel Tests ..

Secondary Cracks . . . . .

Steel Temperature During Test. .

l4. Fracture of the Pull Plate . • . • . .

SUMMARY • • •

BIBLIOGRAPHY. •

TAB~ •••••

FIGURES

iii

Page

24

29

30

31

31

32

34

36

37

Table

1

2

Figure

1

2

3

4

5

6

7

8

9

LISr OF TABLES

Title

Outline of Tests ...•.

Tensile and Charpy Data for Pull Plate steel. .

LIST OF FIGURES

Title

Typical Test setup and Properties of Rimmed steel

Fracture Paths and Properties of Semi-Killed Steel

Thermocouple Locations and Typical Temperature Traces

at Time of Test

Input Circuits and Recording Instrumentation

Instrumentation and Record - Test 13





10 Instrumentation and.Record Test 19

11 Instrumentation and Record - Test 21


13 Instrumentation and Record Test 23



iv

Page

37

41

Figure

16

LIST OF FlGURFS (Con 't. )

Title


17 Instrumentation and Record Test 31


19 strain Distribution at Various Times Test 23

20

2l

strain Distribution at Various Times - Test 25

strain Distribution at Various Times - Test 31

22 strain Distribution at Various Times - Test 32

23 Fracture Speed in Six Foot Wide steel Plates

24 Distribution of strain Across Plate for Various Loads During

Prestraining - Test 32

25 Typical' Photographic Records for Impact Tests

26 Photographic Records for Test 23

27 Typical Crack Paths

28 Crack Paths From Tests With No Records

29 Typical Crack Texture at Initiation Edge

30 Reinitiation of Fracture From Partly Submerged Crack - Test 18

31 Branching of Crack Near Center of Specimen - Test 20

32 Various Secondary Cracks

33 Pull Plate Fracture

v

1

.,

..J...

I. INTRODUCTION

General

The widespread acceptance of steel as a building material may be

attributed to many factors, foremost of which are its mechanical properties.

One of the most important properties of steel is its ductility 'Which permits

local plastic deformation while retaining the useful load carrying capacity

of the member. Normally, failure at ultimate load is characterized by a

ductile fracture involving a relatively large amount of deformation and

energy absorptiono However, under certain conditions of stress, tempera-

ture and geometry, the normal ductility of steel may not be developed aDd

the steel may suddenly, and. without any previous warning, fracture in a

britt.le manner.

Brittle fractures have a long history of incidence and are not

restricted to one type of' structure. storage tanks, pipe lines, bridges,

and. ships (at sea and at dockside) are typical examples of riveted and welded

structures which have failed in a brittle mamler. During the past fifteen

years J extensive research has revealed many of the factors that may contri-

bute to the initiation, propagation and J occasionally, arrest of brittle

fractures. However, a more thorough understanding of the brittle fracture

mec~~ism is required before satisfactory design procedures and construction

methods ror minimizing the possibility of brittle fracture can be developed.

20 Object and Scope

The object of this investigation is to study the propagation of

brittle fractures in wide structural steel plates. To date the primary effort

on the test program bas been to obtain measurements of crack speed and strain

2

response in the vicinity of the crack during the propagation of the frac

ture. Strain records, computed speeds~ and other results of the six foot

wide plate tests which were completed from November 29, 1955 through Novem

ber 15, 1956 as a part of this program, are presented and discussed in this

report 0

In the case of the tests described in this report, r~ed steel

was used for the seventeen instrumented tests, and semi-killed steel was

used for the four specimens of the pilot tests which were not instrumented.

All specimens were 3/4 in. thick and tested in the as-rolled condition

except for one specimen which was tested after being prestrained to approxi

mately tw'o per cent permanent elongation. Each specimen contained two

symmetrical notches, one on each edge; one notch was used to initiate the

fracture and the other notch was used to avoid eccentric loading of the

specimen. All of the specimens were tested at average stresses of 17.0 to

2005 ksi on the net section.

In fifteen-tests, twelve with instrumentation, a brittle fracture

was propagated completely across the plate at temperatures ranging from +5

to -ll degrees Fo Five tests (with instrumentation) were performed to eval

uate the effect of the fracture initiation method on the measured plate

response 0 This latter group of tests was performed at room temperature,

other conditions being similar to those existing for a complete fracture

test. The one additional test was an unsuccessful attempt to initiate a

brittle fracture in a plate of semi-killed steel.

The brittle f'ract'l;JXe of' a pull plate (A-285 Grade C Flange steel)

with no intentional stress concentration is also reported. This fracture

3

occurred at an average net stress of 32.0 ksi and at room temperature. The

crack initiated from the toe of a fillet weld on the plate edge and propagated

across the entire plate.

3. Brief Review of Previous Work

The first wide plate tests at the University of Illinois were con-

ducted under the direction of Professor W. M. Wilson in 1944-46 and involved

* static tests of internally notched steel plates of various widths (1). A

number of these tests resulted in brittle fractures at stresses slightly

above the yield strength.

In 1953, after the failure of two large oil storage tanks in England,

the Standard Oil Development Company undertook an extensive brittle fracture

test program (2,3) of various compositions of steel plate in widths ranging

from 10 in. to 72 in. In these tests the fractures, initiated by means of

an external impact in much the same manner as the tests described in this

report, propagated across the plates at stresses as low as 10,000 psi and at

temperatures in the range of -40 to 0 deg ~ Fe

With regard to the current program, another report (4) describes

the development work and the tests of two foot wide plate specimens which

preceded the work desc'ribed herein. A recent paper (5) presents a summary

of the foregoing work and includes a brief description of same of the six

foot wide plate tests reported herein.

other experimental and analytical work in the field of brittle

fracture mecbanics is reported in publications by G. R. Irwin (6), E. Orowan

* Numbers in parentheses refer to references listed in the Bibliography.

4

(7), A. A. Wells (8), and T. S. Robertson (9). MOst o~.the important work

in this field may be traced through the extensive bibliographies contained

in each of the cited references.

4. Acknowledgment

The tests described in this report were conducted as a part of a

program enti~led "Brittle Fracture Mechanics"- sponsored by the Ship structure

Committee through the Bureau o~ Ships, U. S. Navy, Contract Nabs 65790, Index

No. NS-731-0,34 (SR-137). The members o~ the Brittle Fracture Mechanics

AdVisory Committee to the Committee on Ship structural Design have acted in

an advisory capacity in the planning of this program.

The tests were per~ormed in the structural Research Laboratory,

Department of Civil Engineering, University of Illinois between November

1955 and November 1956. The project is uDder the general direction o~ N. M.

Ne'WIIl.a.rk, Professor and Head of' the Civil Engineering Department. The authors

wish to thank Dr. Newmark, W. H. MUnse, Research Professor of' Civil Engineer

ing" Ro J. Mosborg, Assistant Professor of Civil Engineering (Supervisor of

Project SR-l,34) and V. J. M:!Donald J Research Assistant Pro~essor of Civil

Engineering (in charge of instrumentation) for their helpful advice during

the course o~ the investigation. The authors greatfully acknowledge the

help of T. J .. Hall, T. M. l\Yna.m, W. H. Walker, J. No Chopy, and particularly

S. T. Rolfe, Research Assistants in Civil Engineering, who assisted in the

laboratory work and with the preparation of the figures.

This report has been drawn ~rom a M.S. dissertation of the same

title by R. Lazar which was submitted to the Graduate College of the Univer

sity o~ lllinois in 1957 (10).

5 · Nomenclature

The following terms are commonly used throughout the text.

Dynamic strain Gage -- SR-4 strain gage whose signal is monitored on

an. oscilloscope during the fracture test.

Static Strain Gage -- SR-4 strain gage read at selected static loads

by means o:f a portable strain indicator.

5

Crack Detector -- A single wire (6-in. gage length) SR-4 Type A-9 strain

gage which is mounted perpendicular to the expected crack path and

which is broken by the fracture. A rough measure of the crack

speed may be obtained :from a knowledge o:f the distance between

detectors and the t~e interval corresponding to breaking o:f adja

cent detectors.

Notch Line -- An imaginary horizontal line connecting the notches on

opposite edges of the specimen.

Submerged Crack -- A relatively short, arrested crack which does not

cleave through the plate surfaceo It is usually wedge driven and

characterized by a clearly defined depression on the plate sur

face.

Complete Fracture Test -- A test in which the fracture propagates across

the entire plate 0

Str~ Test -- A test in which the specimen is subjected to the notch

"'eci.t;e-i.mpact method of initiation at the usual test stress, but at

a temperature generally high enough to prevent complete fracture.

6

ll. DF..OCRIPrION OF ~IMENS AND APPARATUS

6. Specimens and Material Properties

All instrumented specimens were cut from 3/4 in. thick Lukens

rimmed steel plates, heat No. 16445, in the as-rolled condition and with

a nomina] width of 72 in.. The depth of ' the specimen insert was either 32

ino or 54 in. as explained in the next paragraph. The insert was welded

with double-V butt welds made with E7016 electrodes to pull plates in a

3,OOO.1000-lb. hydraulic testing machine. The welding was performed in

such a manner as to keep warping and residual stresses to a minimum. The

pull plates were approximately 6 3/4 f't. long, 6 ft. wide and 1 in. thick.

This made the dimensions of the test member 16 x 6 ft. or 18 x 6 ft. in

plan dimension, depending an the size of the insert, with the thickness

changing .from 3/4 in. to 1 in. at the pull plate insert junction. The net

width at the notch line was 2 in. or 2 1/4 in. less than the gross width

noted in Table 1 because of the notches on each edge.

Each insert originally was 54 in. deep with the notches placed 16

in. below the top of the insert for a complete fracture test and 27 in.

below the top for some of the striking testso If a striking test was to be

performed on the insert, it would always be performed before a complete

fracture test. Since the notch lines for these tests were generally 11 in.

apart (vertically), the insert was not materially affected by the striking

test with regard to subsequent complete fracture tests. In two cases a

striking test was performed on the same notch line as the subsequent com

plete fracture test, but from the opposite notch.. After the first complete

fracture test, the cracked portion would be cut out six ino below the test

7

notch line and. the remaining insert would then be 32 in. deep. The notch

line for the second complete fracture test would be at the center of the

remaining portion of the insert, or 16 in. from either the tap or bottom

weld. One insert (Test 32) was prestrained to approx:ilnately two per cent

permanent deformation before testing. The check analysis and mechanical

properties of the rimmed steel are presented in Fig. 1, together with a

line diagram of a specimen and a photograph of a typical test setup.

Four pilot tests were performed on a 3/4 in. thick USS semi-killed

steel plate, heat Noo 64 M 487, with a nomina..l width of six £'t. The check

analysis and mechanical properties of' this steel are shown in Fig. 2,

together with photographs of the crack paths resulting from the tests. ,

70 Fracture Initiation

One of the first problems encountered in any brittle fracture

propagation test program is that of finding a consistent method of fracture

initiation. Idea1.1y, the conditions .for the tests should be similar to

actual service conditions; this suggests limiting the stress to normal work

ing stresses and the temperature to ordinary service temperatures. However,

at present the static initiation of brittle .fractures under such conditions

cannot consistently be controlled in the laboratory. As a matter of inter

est, of' the forty-odd tests performed in the laboratory as a part of this

program only one failure involving static initiation occurred (this is dis

cussed in Section 14).

After some preliminary work (4,5) the so-called "notch-wedge

impact" method of initiation was perfected and used for all the tests. The

8

notch-wedge-impact method of fracture initiation involves the driving of a

wedge into a prepared notch in the edge of the plate. The driving of the

wedge causes a very high rate of strain at the tip of the notch and for

certain steels under selected conditions of stress and temperature, pro

vides a consistent method of initiating brittle fractures. Only once did

this method fail to initiate a brittle fracture with the stresses and tem

peratures employed in the tests. As explained in Section 12, this method.

of initiation apparently does not affect the propagation behavior of the

fracture significantly.

The notch used in Tests 12 through 25 bad a total length of 1 in.

The first 7/8 in. of the notch was four hacksaw blades in width (approxi

mately 0.141 in.), the next 1/16 in. was one hacksaw blade in width (approx

imately 0.034 in.) and the last 1/16 in. was a jewelers' saw-cut in width

(approximately 0.012 in.). For Test 26 and all subsequent specimens, a

notch baving a total length of 1 1/8 in. was used. The first cut was made

1 in. long, with all other dimensions remaining as noted above. The wedge

used was a standard. 1 in. octagonal cold chisel (included angle of tip was

approximately 160) cut to a length of' 4 3/4 in. and weighing 1.0 lb.

The impact was provided by a gas-operated piston device. The

activating pressure and the stroke of the piston can be varied to produce

any desired impaCt up to 3,000 :ft. lbo The pressure is supplied by bottled

nitrogen gas. A stroke of five in. and a pressure of 280 psi were used in

all the tests. This resulted in a theoretical energy output of approximately

1200 ft. lb. To absorb the reaction of the device during acceleration of

9

the piston, the device is tied to a weight (approximately 120 lb.) which

bears against the far side of the specimen at the notch line.

Several methods have been used to calibrate the piston device in

order to determine the amount of energy delivered to the wedge. The first

attempt involved the measurement of the velocity of the piston which was not

very successful. The most recent method is based on the deformation of brass

cylinders which are 1 1/2 in. long and 1 1/2 in. in diameter; this method is

not exact but gives satisfactory results.

The latter deformation method involves two steps: (1) tests in a

drop-weight machine to obtain the relationship of energy input versus defor

mation of the brass cylinders; and (2) tests of simj] ar brass cylinders with

the gas-driven piston device at various theoretical energy outputs, espe

cially the five inch stroke and 280 psi pressure used in all the tests.

These calibration tests showed that the piston device was occasionally deliv

ering a nruch lower energy output than anticipated, sometimes do'Wn to 40 per

cent efficiency. This fact may possibly account for the failure to initiate

and propagate a brittle fracture in Test 18. A general overhaul and slight

modification of the piston device was made between Tests 25 and 26 as noted

in Table 1. The recalibration results indicated that more consistent opera

tion was then obtained. The efficiency of the modified piston device as

determined by the deformation method was approximately ninety per cent, or

an actual energy output of about 1,080 ft. lb. for a theoretical energy

input of 1,200 ft. lb.

10

8. Coo~ing Apparatus

The cooling of the specimen to the desired temperature is accom-

plished by placing crushed dry ice into specially made 3 in. thick containers

vrhich are hung against the sides of the specimen. Each container is approx-

imately 2 fto by 6 ft. in plan dimension, and three containers are connected

to cover an area of 6 ft. by 6 ft. The tanks are shown in place in Fig .. 1. oJ·

The center tanks are recessed so that neither the ice nor the tanks come in

contact with the specimen near the gage locations. The specimen temperature

obtained by this method of cooling is quite uniform near the notch line,

varying only a few degrees across the entire plate. The thermocouple loca-

tions and typical temperature traces at time of test are presented in Fig. 3.

9 . Instrumentation

(a) Sensing Devices

The strain measurements were made 'with Baldwin SR-4 Type A-7 strain

gages (1/4 in. gage length). These gages were used to obtain both the static

a¢ dynamic gage readings. They were attached to the specimen using a thin

layer of Duco cement, dried as speCified" and then covered with a moisture-

proofing material.. To minimize temperature induced strains, care was taken

to ensure that an equal length of lead wire was used for each gage, and also

that the lengtb of' wire cooled with the specimen was constant for all the

strain gages.

The crack speed was measured through a system of' surface crack

detectors.. These detectors (-SR-4 TypeA-9 single wire strain gages, 6 in.

gage length) were cemented to the specimen using a thin layer of' Duco cement.

As the crack passed and broke the detector, an electrical circuit was

11

interru:pted. From a knowledge of the time corresponding to breaking of the

detectors, and the distance between the detectors, the average surface speed

of the crack may be computed.

The speed of the crack was also computed on the premise that the

strain signals peaked. at the instant the crack passed the strain gages. How

ever, observations indicate that the time of peaking is affected by the dis

tance of the crack path from the gage location. Therefore a slight error

was introduced when gages spaced at varying distances from the crack path

were used to calculate the speed.

It must be emphasized that these methods of s:peed measurements con

stitute an average surface measurement only, and thus may not give the true

speed of the crack front; also, the exact positions of neither the surface

crack nor the interior portion of the crack are known at the instant the

detector breaks or the strain gage peaks. Thus, in computing the crack

speeds it is assumed that all the detectors and strain gages (in this case,

strain gages close to, and a constant distance from, the crack) respond

similarly. These methods of speed determination were considered to be the

best available approximation. However the equipment limitations, the dif

ficulty in defining the actual crack, and the possible detector and strain

gage inconsistencies are recognized. All speeds noted herein are rounded

off to the nearest 50 f'ps.

Two types of triggers were used in these tests. A plate-surface

trigger (SR-4 Type A-9 strain gage denoted by T in the diagrams) was mounted

about one in. beyond the tip of the initiating notch; the breaking of this

gage by the fracture started the recording equipment. The plate-surface

trigger allows the use of a short time base for the test records (approximately

12

three milliseconds) since the crack is already started when the trigger

gage is broken. The external trigger, an electrical circuit activated by

movement of the wedge and denoted by EI' in the, diagrams, requires a longer

time base (approximately six milliseconds) to allow for the time lapse

between the triggering and the actual initiation of the fracture. The

external trigger permits the recording of signals from gages close to the

fracture initiation point; this is not possible with the plate-surface

trigger. In the latter case a short record is obtained while in the former

case a longer, more complete record is obtained. Figure 4 shows the trigger

circuit. In this diagram the triggering devices shown are a SR-4 Type A-9

strain gage, (plate surface trigger), a micro-switch (~) and a strip of

aluminum foil (the external triggers). Any one device can trigger the

circuit but all three types of triggers have been used as a safeguard in

recent tests.

Ten copper-constantan thermocouples are located at' various points

across the specimen to provide a temperature profile during cooling of the

specimen. These thermocouples are installed in No. 54 drill holes about 1/4

in. deep.

(b) Recording Devices

A maximum of nine channels of high-speed cathode-ray oscilloscope

equipment with photographic recording are presently available for strain

and crack speed signals.

eight of these ch:annels.

Four dual-beam cathode-ray oscilloscopes provide

The photograph in Fig. 4 shows nine channels of

oscilloscope equipment, the temperature recorder and calibrating oscillator-

13

All signals are recorded photographically as a ~ction of a

common time base supplied from the single channel oscilloscope. This same

oscilloscope provides all nine beams with the desired unblanking and inten

sifying signals used to minimize fogging of the record before and after

the test period.

The four traces from two dual-beam oscilloscopes are optically

superimposed on a single frame in the interest of maximum photographic

definition. Thirty-five millimeter strip-film. ca.m.eras (used as single

frame cameras) are employed with the dual-beam equipment and a single-frame

thirty-f'ive millimeter camera is used with the single-channel oscilloscope.

This equipment is shown in the block diagram in Fig. 4.

Six of the oscilloscope channels are sufficiently sensitive to

allow at least 1 1/2 in. of trace deflection for 1,000 microinches per inch

of' strain. The other three channels have about one-third this sensitivity.

Whenever possible the latter channels are used to record the highest electri

cal magnitudeso The frequency response of' the single channel oscilloscope

is flat from 0 to 1,000 kc 0 The response of' the dual-beam units is f'lat

f'rom 0 to 100 kc and decreases not more than fifty per cent at 300 kc.

Since the majority of' the records are two or more milliseconds long and the

recorded signals do not approximate step f'uDctions, the latter response is

considered adequate. For example, consider a time base of two milliseconds,

a frequency of' 100 kc per second and a scope f'ace four in. long. Each com

plete cycle or period should then be 0002 ino long 0 Since the recording

spot on the scope f'ace has to be of a definite size and intensity (approx

:i:ma.tely 0001 in. in diameter) to register properly on the film, the resulting

14

record at this high frequency would be a solid band, the height of which

would be the amplitude of the signal. Thus the band width or time defini

tion of the recording equipment surpasses the photographic or optical def

inition of the record. The band width; or frequency response, of the mea

suring gage and its associated wiring has been assumed to be in excess of

any of these values.

The temperature is recorded during the cooling process in order

that the cooling rate and the temperature gradient can be observed before

the test. For this purpose an automatic recorder which provides a sensiti

vity of about 1°F per 001 in. on the record is used. The various thermo

couples are sequentially sampled by a motor driven switch and direCtly

recorded in degrees Fahrenheito

(c) Input Circuits

The, signals fed to the cathode-ray recording equipment consist of

a sweep triggering pulse followed by strain and crack location signals. The

detectors, which fail as the crack crosses the plate, open an electrical

circuit 0 Each detector feeds to the recording channel a different step

voltage whose amplitudes are in the ratio of 1:2:4:8:16. Each step has a

different magnitude and can be identified with the particular detector to

which it is connected, thereby providing a positive identification of

sequence 0

The time base is initiated by the trigger. Opening the trigger

circuit removes the bias signal from a triggering thyratron and allows it

to start conducting. The step voltage, which results at the start of con

duction, is fed into the standard circuits of the single channel oscilloscope

15

unit. Reinitiation cannot occur until the thyratron is reset manually.

This prevents subsequent multiple sweeps which may be triggered by chatter

of the initiating wedge, accidental grounding of the broken trigger wire,

etc., which would obscure the traces of interest on the single recorded

frame"

The strain gages are connected in the customary wheatstone bridge

circuit.. Dul:r.Imy gages which complete the bridge circuit are mounted extern

ally to the specimen 0 These bridges are excited by direct current and their

outputs .fed to the recording channelso Typical input circuits are shown in

Figo 40

(d) Measurement Procedure and Calibration

The strain measuring channels are calibrated by shunting gages with

a resistance whose equivalent strain value is known or measurable. Both the

active arm and the adjacent dummy gage are shunted successively to obtain

compression and tension calibrations" Only one calibrating value is used

because other tests indicated that the linearity of the recording system

was adequate within the limit of' resolution of the record" Crack detector

calibration is obtained by successive~y opening switches in series with the

various detectors and recording the trace steps 0 The time axis is calibrated

by putting a time .signal of' known f'requency on all channels simultaneously

and photographing one sweep. This is done immediately a:fter the test is

completed ..

Although the deflection plates are connected in parallel and are

driven from a common amplifier, individual construction of' the various guns

and de~lection systems results in slight horizontal displacements between

16

the traces and .ill slight differences of de.flection with a simultaneous signal.

The stab"ility of gain magnitude and trace deflection in this system was

found to be satisfactory by a series of ,investigations and by the consistency

of trace lengths and locations in the various tests.

(e) J)3.ta Reduction

A feature of the data reduction that may not be a standard proce

dure is the method of tying the various traces together with respect to time

and the significance of the time axis values. In general, some arbitrary

point is taken along the time base and called zero time. This mayor may

not correspond to the earliest point on the recorded traces. The point is

selected near the early portion of' the sweep at the first peak of the time

calibration sinewave. This provides a convenient and definite reference

point common to all traces. The record is reduced in the customary manner

of reading signal amplitude against time, each trace being read with an

individual calibration on both the time and signal axes. The earliest time

noted for any record is same finite but unknown period of time after the

breaking of the sweep trigger wire, approxima. tely 20 microseconds 0 Thus the

earliest recorded time is a variable.. This time has been tacitly assumed

smalJ.. and occurs some finite time a.:f'ter the initiating wedge enters the

plate.

10. Test Procedure

The notches are cut in the edge of the specimen insert after it

is welded to the pull plate in the testing machine. In the case of the one

prestrained plate, the prestraining was done before the notches were cut

into the plate edges. The strain gages were then attached and the

17

thermocouples installed. The strain gages were checked at room temperature

by cycling (ie. loading and unloading) the specimen to the test load.. This

was done in order to check the gages and the strain distribution in the

specimen. Since many of' the inserts were slightly warped, sizable strain

residuals were sometimes observed f'ollowing one load cycle. To reduce

these residuals the specimen was usually cycled f'our times but never stressed

higher than the test load~

All the wiring adjacent to the cooled specmen was sprayed with a

plastic compound to improve the insulation. Tbegages and wiring also were

covered with a plastic curtain to minimize the amount of condensation coming

in contact with the instrumentation. This curtain also prevented stray

pieces of' dry ice from coming into direct contact with the steel plate.

After the cooling tanks, gas-operated piston device, and reaction

weight were suspended from the upper pull plate, the instrumentation was

connected and checked. The dry ice tanks were f'illed, and as the desired

test temperature was approached, the test load was applied to the specimen

and the recording devices were calibrated. As the specimen reached the tem

perature selected for the test, the gas-operated pis~on device was pressur

ized and fired.

Tbe static strain gage readings were recorded as soon after the

test as possible. In the case of complete fractures an estimate of the resid

ual strains in the plate may be made from these readings. Also at this time

a check of the dynamic strain gages was made to aid later interpretation of'

the test records.

18

llI. RESULTS AND INTERPRETATION OF TESTS

11. Test Records

The results of the instrumented tests are shown in Figs. 5 through

22. The tables in each figure indicate the position of the strain gages,

crack detectors, trigger, the vertical position (Y ) of the crack with resc

pect to the notch line, the strain level for each strain gage at test load,

crack speeds as determined from the detectors, and the test conditions. A

record of the strain-time relationships as obtained from the ~ic strain

gages is shown. In all cases the strain traces are plotted to start at a

strain level corresponding to the initial test load strain; thus, the strain

values shown may be considered as absolute strain values. The detector

breaking time is indicated on the record to denote the approximate location

of the crack front.

The quality of the records from the tests varies considerably.

Typical enlarged photographic records of strain traces are presented in Figs.

25 and 26. These were considered to be of good quality. Poor records may

result from many causes, for example, faulty or late triggering, incorrect

focus of the camera or the oscilloscope, or poor lead wire connections. A

record is considered poor also when the strain traces overlap on the record-

ing film to such an extent that it is not possible to determine exactly to

which strain gage the ensuing trace belongs. This generally occurs in the

latter part of the record if it occurs at all. A partial record is one on

which some of the strain traces are recorded, while the remainder are not.

This may be due to a number of factors which cause a failure of the gage or

19

gages, for example, condensation on exposed lead wires, or equipment failure

during the tests.

The strain signal in most records is an erratic, oscillating trace

after the first 1.5 to 2 milliseconds, ie. after the plate breaks completely

(for an example see Fig. 13). This oscillation may be the result of such

factors as motion of gage lead wires, ringing of the plate due to the impact

force, vibration of the two parts of the plate, etc. Many of the strain

signals have high frequency noise superimposed on the actual signal (for an

example see Fig. 18). Normally the noise level was very low and has been

ignored in plotting the record in order to clarify the resulting trace. In

the few cases that a high noise level was recorded the disturbance occurred

at the same time and to about the same degree on all the traces. This was

attributed to an electrical disturbance since all gages are fed from a com

mon source and. are grounded in cozmnon.

To study the strain behavior in the vicinity of the fracture, the

strain gages must be located close to the anticipated fracture path. The

effect of a fracture passing either through or very near (within 1/4 to 1/2

in.) a strain gage may affect the recorded traces in several ways. The

trace for such a gage often exhibits an extremely rapid rise and leaves the

scope face (for the sensitivities used in these tests), and mayor may not

return within the duration of the record. Also, since all the gages have a

common ground wire, the destruction of one gage may cause a voltage jump (or

occasionally noise) in the other gages (for an example see Fig. 14).

20

12. striking Tests

The object of this series of five tests was to evaluate the effect

of the notch-wedge-impact method of crack initiation on the strain response

of the specimen. In the striking tests the specimen was subjected to the

notch-wedge-impact method of crack initiation, but at a temperature gener-

ally higher than the temperature for the complete fracture tests in order to

prevent crack initiation. The standard notch, wedge, and theoretical impact

force was used in these tests. The stress varied from 18.0 to 18.5 ksi; the

temperature was approx:i.mately 750F for four of the tests (Tests 16, 17, 21

and 30) and approx:i.JIla.tely O~ for one test (Test 18).

In three of these tests the strain response in the general vicinity

of the notch was studied. Test 17 (Fig. 8) initiated a 1/2 in. submerged

crack and all gages showed an :i..Imnediate response, several as high as 250

microinches per inch. Test 21 (Fig. ll) showed no sign of any submerged

cracks but all gages showed an immediate response, some as much as 220 micro-

inches per inch of strain. It is of interest to note that gages 3 and 9,

back to back on the specimen, show strain changes of opposite signs. No

record was obtained in Test 16 because of a ~aulty trigger circuit.

The other two tests of this series were concerned with the strain

response of gages located on the fracture-test notch line; the same gages

were subsequently used in a complete fracture test. Test 18 (Fig. 9) is the

only six foot ,"'ide plate specimen which thus far has failed to fracture com-

pletely" under normal fracture conditions. As explained previously in Sec-

tiOD 10, this may be due to the gas-operated piston device delivering a

slightly reduced starting energy. The test resulted in a partly submerged

i I

C

I c

1 i • c ~

~ til

t • c c <:

J

.../

21

crack" approximately 2.3 in. long. This crack is considerably longer than

the cracks :formed by similar tests at room temperature. With the exception

of gage 1, the gages showed strain responses o:f not more than 50 microinches

per inch. Gage 1 peaked to approximately 1,000 microinches per inch, and.

retained about 300 micro inches per inch o:f permanent set, probably because

of its proximity to the crack. Test 30 (Fig. 16), at room temperature, did

not show a~ signs of a submerged crack. The strain response was not over

50 microinches per inch for any gage. The notches used for Tests 18 and 30

were the source of secondary cracks when the inserts were later fractured

completely in tests in which the fracture was initiated from the opposite

companion notch.

It was concluded from the above tests that the present notch-wedge

impact method of fracture initiation produces a relatively small strain res

ponse as compared to the strain response which is recorded during the frac

ture tests. The records indicate that the impact is felt throughout the

plate; however J the strain magnitude, particularly at the center and far side

of the plate, is small.

A question which remains unanswered by these tests is how far must

a crack be driven by the impact force to enable the fracture to propagate

across the entire plate. Obviously, other factors such as stress (or strain

and related strain energy-), temperature, and :imparted :iIrIpact energy-, influ

ence the propagation. The formation (or non-formation) of submerged cracks,

and the variation of their length under similar physical test conditions"

admittedly are not completely understood; on the basis of Test 18, it would

seem that in the range of' stress and temperature in which these tests are

22

being conducted~ the relationship between external impact energy-and driven

crack length must be fairly critical.

13. Complete Fracture Tests

(a) Fracture Speed

The speeds of propagation of the brittle fracture on the plate

surface for the six foot wide plane plate tests are shown in Fig. 23. The

speeds as measured by the crack detectors varied from 2,150 to 3,800 f'ps and.

from 1~800 to 7,550 fps as measured by the strain gages. This wide variation

in speed occurs despite the fact that all the tests were performed under sim

ilar test conditions. However, seventy-five per cent of all recorded speed

data is in the 2,100 to 3,900 f'ps range.

The crack detector.s spaced at intervals of approximately 12 in.

appear to give more consistent values of speed than the strain gages. Ninety

five per cent of the computed speeds from crack detectors are in the 2,100

to 3,900 f:ps range, while only fifty-five per cent of the computed speeds

from strain gages are in this range. other evidence of inconsistencies in

the two methods of measurement may be seen in Test 15 where the speed of the

crack across the latter part of the plate was 4,350 fps on the basis of the

record :from the vertical dynamic strain gages on the east face of' the plate.

For this same distance on the same section of plate, the crack detectors,

also on the east Side, gave an average speed of 2,600 f'ps. The vertical

strain gages on the west side show a speed of 2,100 f'ps in this region. In

Test 19~ the vertical strain gages indicate a speed of' 7,550 fps, the hori

zontal strain gages 4,850 fps, and the crack detectors approximately 3,500

£':ps. In this particular test, the speed for the section between detectors

23

D and E is omitted; detector E was broken in two places, once by the main

f'racture and once by a second.a.r.Y fracture, and it is not known which break

occurred first. All these gages (detectors and strain gages) were located

in the same section on the east face o:f the plate. Again in Test 31, the

speeds on the :first half o:f the plate agree closely with each other and with

other speeds recorded on this section of the plate, while· on the second half

a considerable di:fference in values was noted. However, the speeds as deter

mined by the detectors :for Tests 13, 14, 15, 19, 22 and 31 all agree fairly

well with each other.

The speed of fracture propagation appears to reach a constant value

within the first :four to six inches of the fracture. Test 32 indicates a

speed of 3,150 :fps in the first foot of the plate. Tests o:f this and other

investigations (4), also indicate this same tendency. In most cases the

magnitude of the speed (approxiIDately 3,500 fps) as measured with the crack

detectors, remained about the same as the crack propagated across the plate

spec linen 0

A study of all the speed data from tests of six foot wide plates

(including speed measurements made as part of the Crack Arrestor study, Proj

ect SR-134) in.dicate no definite speed versus average static stress, or speed

versus average temperature relationship, although the average net stress

rang~d from 18 to 33 ksi, and the temperature ranged :from +5 to -33°F. A

slight increase of speed for lower temperature and higher stress seems to

be apparent :from the Crack Arrestor tests, but this is not consistently

observed. The speed of fracture propagation on one test of a semi-killed

steel plate (Project SR-134 data) was not noticeably dif~erent from the

speed of fracture noted in the rimmed steel plate tests.

24

In conclusion, considering each specimen individually, and the

group of specimens as a whole (all tested under similar conditions), it

appears that brittle fracture speeds measured by widely spaced crack detec

tors on the plate surface are more uniform than those computed £'rom simi

larly spaced strain gages. The variation in measured speed is often more

apparent over short lengths o~ the plate. However, there is no reason to

believe that the fracture progresses uniformly across the width of the

plate. It is conceivable that, as the inner portion o~ the fracture pro

ceeds across the width of the plate, the surface may open intermittently;

i.e. the sur~ace fracture may start, skip a section, and then continue on

with the skipped section breaking slightly later. This concept might help

explain why adjacent or back-to-back strain gages do not peak at the same

time, and may also explain many of the apparent inconsistencies in speed

measurements. However, for the tests made under approximately similar con

ditions of stress, temperature, and impact, it seems reasonable to expect

that the average speed of propagation £'rom plate to plate should be approx

imately the same. In any evaluation of the speed data, it must be recog

nized that the methods used provide only app~oximate measurements, but were

felt to be the best methods available (Refer to Section 9 for a discussion

of speed measurements).

(b) Dynamic Strain Measurements

strain-time relationships are shown for ten tests, Figs. 5 through

18. The majority of the strain measurements were made with vertically oriented

25

strain gages in the vicinity of the crack path. Also, several strain traces

from horizontally oriented gages and one strain trace £'rom a gage oriented

450 to the vertical were obtained in the vicinity of the crack.

During the course of the fracture, the vertically oriented strain

gages in the vicinity of the crack path display a similar behavior in that

the signal peaks when the crack approaches or passes the gage location. How-

ever the precise position of the fracture at the time the peak is reached,

is uncertain. The peaks for back-to-back gages, and gages mounted on the

same side and only 0.5 in. apart, were found to be as far apart as 0.3 milli-

seconds (Figs. 5 and 7). In Test 13 (Fig. 5) it is interesting to compare

the signals from strain gages 2 and 4 which were mounted back-to-back at the

center of the plate. The difference in time between the peaking of the two

gages is about 0.4 milliseconds, which for ~~ average speed of crack propa-

gation of 3,400 f'ps would indicate one side of the fracture preceeded the

other by 16 inches. In addition there is a sizable (1,200 microinches per

inch) difference in the amplitude of the strain peaks.. Also in this tes-t,

gage 2 was approached by the crack path before detector C, but the strain

gage peaked 0.16 milliseconds after the crack detector broke.

The foregoing is one basis for the suggestion that the fracture

of the plate surfaces may not be continuous and symmetrical. In addition,

it is found that upon recovery, some of these gages show an increase of

strain over the initial strain, several strain gages show a decrease, and

several show no change at all. To some extent, but not entirely, this dif-

ference in behavior may be correlated with the distance of the strain gage

from the fracture, but just as likely may be related to stretched lead wires,

etc., as discussed later in this section.

.1

The magnitude of the peaks follows no set pattern) although in

comparable records (Tests 23, 24, 31 and 32) there seemE to be a slight

increase in the magnitude of the strain peak for gages located closer to

the fracture path. However this behavior is not consistent" as back-to

back gages which are the same distance from the crack) sometimes have peaks

of greatly differing magnitudes 0 This inconsistency in strain magnitudes

has been noted particularly in records from tests in which the crack passed

through at least one strain gage~ This effect was discussed in Section 11.

The magnitude of peak strains from gages further away from the

crack path is less than the peak strain for gages located very near the

fracture path~ For example J the magnitude of the :peak strain was approxi

mately 1,400 microinches per inch for gages three to four inches away from

the crack path in Test 23, and approximately 1,100 microinches per inch for

gages six to seven inches away from the crack path in Test 320 This would

j.:c.dicate a rapid decrease in magnitude of the strain peak for points :further

away (vertically) from the horizontal fracture; this corresponds to observa

tions reported in Reference (4). It is important to note that the peak

strain magnitude does not show any definite correlation with the gage posi

tions across the plate 0 It. was anticipated that~ as the crack progressed

aGross the plate, it would produce strain peaks o.f lncreasing magnitude;

however, neither this nor aD-0'~ other particular tendency vras observed.

Arter reaching a peak value j the strain signals move tow~rd the

zero strain level. However:many of the traces d.id not return precisely to

this \~lueas noted in Figsa 5, 6 and 120 This variation in leveling-off

or TL~l strain may be caused in part by such effects as the relaxation of

27

residual strains, inelastic strain resulting from fracture, and stretching

of the lead wires after fracture. Also, a comparison of strain readings

made immediately before and ·after the test, with gages used for static mon

itoring purposes, reveals an erratic array of residual strain values; how

ever, in the majority of cases in which the gages were at some finite dis

tance from the crack (greater than 1 to 2 inches) and did not have pulled

lead wires, etc., the residuals (final strains) were smallc

It has been observed that the static strain level at test load

sometimes varies considerably both across the width of the test plate and

through the thickness. Across the width of a plate on one side only,

excluding that region immediately adjacent to the notches, base strains

have been found to vary by as much as 200 microinches per inch. In the

thickness direction a difference in strain values of as much as 200 micro

inches per inch has been noted for an average strain level of approxiInatel:y

600 mic.roinches per inch. The strain response during crack propagation has

been studied to try to ascertain the effects of these large differences in

base strain; it is believed that both the differences in dynamic peak

values and the time lag in peaking of back-to-back gages may be affected to

.some degree by the variation in base strain~

Test 32 (Figs. 18 and 24) was performed on a steel plate prestrained

to approximately two per cent strain. It was believed that the prestraining

would reduce the strain differential in both the width and thickness direc

tions and thus gages mounted back-to-back would have records which would be

in better agreement, both as regards time of peaking and magnitude of strain.

The test results indicate that the magnitudes of the strain peak were quite

28

uniform ~or back-to-back strain gages, but the time o~ peaking was still

inconsistent. In this test, gage 6 peaked a~ter gage 1 and gage 7 peaked

a~ter gage 2, but gage 8 peaked be~ore gage 4. This one test would seem

to indicate the dif~erences in dynamic peak strain magnitudes and the time

lag in peaking o~ back-to-back gages are probably not a~fected markedly by

the variation in base strain.

The distribution across the plate of vertical strain at various

times during the fracture is sho'WIl in Figs. 19 through 22 by bar graphs.

Figures 19 and 21 seem to indicate that a vertically oriented strain gage

located close to the crack path (up to 2.3 in.) is unaware of the approach

ing fracture until quite suddenly the strain trace exhibits a rapid rise

followed by a rapid drop, i.e., there is little change in the strain level

on the uncracked portion of the plate until some time just prior to peaking.

This would indicate that even though there is a reduction in the net section

as the crack progresses across the plate, the strain (and corresponding load)

on the remaining section does not have time to change; thus, there is no evi

dence of a gross redistribution of load on the net section during the frac

ture process. A study of' strain response patterns in Figs. 19 through 22

suggests a strain concentration (associated with the crack front) which tra

vels across the plate, leaving a brittle fracture in its wake.

Some of the tests contain records from gages 8 and 9 which were

located about 104 inches below the notch line, as sho'WIl in Figs. 10 and 12.

The gages are vertically oriented, and in order to eliminate the effect of

bending in the plate, the response from back-to-back gages is averaged elec

trically. The response of these gages is very similar in both tests. Both

29

gages begin to show a decrease in strain at the moment the record commences,

with the gage nearest the striking edge dropping off more rapidly than the

other gage; the rate of change in strain increases, particularly after about

half the plate is fractured. A record of these gages from another test (Proj-

ect SR-134 data) with a longer sweep time indicates that these two gage sig

nals oscillate for some time after fracture, and eventually approach the zerc

load strain value.

Tests 19 and 22 (Figs. 10 and 12) show the records for strain gages

oriented horizontally. The strain records for these horizontal gages are

somewhat different than those observed in the two foot wide tests (4). In

the latter case, the records usually indicated a reduction in the initial

compressive strain as the fracture approaches the gage, followed by a sharp

compressive strain peak at the time the companion vertically oriented gage

peaked in tension. This general type of behavior is seen in Fig. 12, but

not in Fig. 10; in the latter case, there is a large tension peak at the

time there ~ould normally be a compression peak. Although the precise rea

son for this difference in behavior is not known in this case, it may be

due in part to the fact that the fracture passed very close to the particu

lar gage in Test 19 (Fig. 10).

Tbe behavior of a gage oriented 450 to the vertical is quite simi

lar to t~t of ~n adjacent vertically oriented gage, except that it peaks

somewhat l~ter. A typical example is shown in Fig. 12.

( c ) C r-iC 1: Fa th and Texture

The fracture paths have not shown any tendency to follow a parti

cular direction. The great majority of the fractures slope upward from the

point of initiation, then level off or wander. Several crack paths for 6

30

ft. wide plates are shown in Figs. 27 and 28. The crack paths shown in Fig.

28 are from the tests in which no strain records were obtained. The maximum

deviation of a crack path from the notch line for the wide plate tests was

approximately 7.3 in. (Test 32).

The texture of the brittle fractures may vary considerably from

test to test and from one part o.f' the plate to another. The texture of the

fracture surface may range from very flat and smooth (chevrons indiscernible)

to very coarse (chevrons may protrude up to approximately 1/8 in.). Typical

examples of crack texture may be observed in Figs. 29 through 32. In some

specimens the fracture texture is so coarse that small pieces of metal are

torn completely away from the parent plate. The texture for tests of rimmed

steel, prestrained rimmed steel and the semi-killed steel was similar in

that it could not be correlated with other test conditions or results.

It was thought that some correlation might exist between the tex

ture of the fractured surface and the speed of propagation, namely, the

smoother the texture, the faster the speed, and vice-versa. However no def

inite correlation is evident at this time. Measurements indicate a reduc

tion in thickness in the region of coarse texture of .010 in. to .020 in.

(1 to 2 per cent of plate thickness) while there is only .001 in. to .004

in. reduction in ~hickness (0.1 to 0.3 per cent of plate thickness) in

regions of fine texture. This was noticed in the tests of semi-killed

steel specimens also.

(d) Semi-Killed Steel Tests

Four tests (Tests 26 to 29) without instrumentation were conducted

on a semi-killed steel with a Charpy V-notch 15 ft. lb. value of OOF, to

31

determine the stress level necessary for fracture propagation. An interest

ing feature of these tests was that Test 26 at 17,000 psi and -loF did not

fracture, while Test 29 at 17,000 psi and -20 F did fracture. In these tests

the original insert was 3/4 x 60 x 72 in. and after each test the fractured

portion of the plate was cut out and the remainder rewelded to the pull plates

so that the insert for Test 29 was only 3/4 x 16 x 72 in.

Complete fractures were obtained in the last three tests (See Table

1, Tests 27, 28 and 29) leading to the conclusion that the test conditions

required for propagation of a brittle fracture in this semi-killed steel

approach those of the rimmed steel presently used.

( e) Secondary Cracks

A secondary crack is a brittle fracture generally initiated during

the test from the notch opposite the test notch. The chevron markings indi

cate that these secondary cracks propagate toward the advancing brittle

fracture from the notch opposite the point of initiation. They either

arrest within the plate or terminate by joining the main fracture. Typi

cal secondary fractures are shown in Fig. 32. Figure 30 shows the far edge

of the specimen for Test 18 after fracture. The submerged crack from the

previous test on this insert, which propagated only 2.3 in. as shown by the

arrow, reinitiated and joined the main fracture which approached from the

left. Figure 31 shows a close-up of the specimen from Test 20 (Refer to Fig.

29 for the crack path) where the fracture started to branch. There is no

strain record for this test.

(r) Steel Temperature During Test

On several spec:imens an attempt has been made to collect data

involving the change in temperature resulting from the fracture phenomena.

32

Several cooling records beginning a few minutes be.fore the test and extend

ing for several minutes afterward are shown in Fig. 3. Changes of as much

as several degrees F have been noted in a number of the tests immediately

following fracture, but the results are inconsistent and at this time no

conclusions may be drawn.

14. Fracture of the Pull Plate

This fracture resulted during the prestraining of the specimen

insert for Test 32. The fracture occurred at room temperature (approxi

mately +790F) and at an average stress of 32 ksi. The fracture initiated

from the toe of a weld on the edge of the pull plate. The weld held a

bracket which was used to support the initiation and cooling eqUipment for

the regular tests. There was no external load on the bracket at the time

of failure. A secondary crack about three to four in. long was initiated

from the toe of a weld on the opposite edge of the pull plate.

The brittle fracture had a distinct shear edge or thumbnail at

the beginning (see Fig. 33). The texture of most of the fracture varied

from coarse to very coarse.

T~i~ pull plate has a long strain history, but the addition of the

welds on tee edges was quite recent. The original check analysis and tensile

properties ~re shown in Fig~ 33c Recent tensile and Charpy V-notch data are

presente~ iL T~t}e 2~ The recent tests show a lower yield strength, and a

higher ffiJ.ZX.J.:: strength" than originally reported. Of particular interest

is the exhaustion of ductility which is indicated by the strain correspond

ing to the beginning of strain hardening (€sh). This value is tabulated in

Table 2 and indicates that the previous strain history of the plate had

33

exhausted roughly one-half of the foregoing strain (€sh) normally available.

The Charpy V-notch data appear to be in line with other data for the same

type o.f steel as reported by the Standard Oil Development group (3).

34

IV. SUMMARY

A fundamental study of the propagation of brittle fractures in

six foot wide steel plates is described in this report. The plates were

tested under similar stress and temperature conditions, and the fractures

were initiated at an edge notch by a wedge subjected to an impact. The

specimens were instrumented to provide a record of strain response and

crack speed as the fracture propagated across the plate.

Striking tests, in which the specimen was not fractured, indicate

that the strain response resulting from the impact-wedging action is rela

tively small when compared to the strain response recorded during the frac

ture process. Although the records indicate the impact is felt throughout

the entire plate, it appears that the strain at the center and far side of

the 6 ft. wide plate is not materially affected by the wedging action.

The majority of the strain and speed measurements recorded in the

fracture tests have been made in the immediate vicinity of the fracture

path. Strain magnitudes exceeding 2,500 microinches per inch have been

measured on the plate surface near the fracture, with negligible permanent

set remaining after fracture. In general, the nearer a vertically oriented

gage is to the fracture path, the sharper and greater the magnitude of the

strain pulse; as the distance increases, the strain pulse extends over a

longer period of time, but the precise shape of the pulse depends on the

distance from the fracture path. Thus far vertically oriented strain gages

in front of the crack indicate that there is negligible strain redistribu

tion on the remaining section ahead of the crack.

35

strain signals from gages adjacent to the fracture and. mounted back-

to-back on the plate, or immediately adjacent to each other, attest to the

discontinuous nature of the surface fracture; in terms of fracture length the

time lag between strain trace peaks in the case of gages mounted back-to

back has amounted to a differential crack length on the two surfaces of as

much as 16 in. Such measurements may help to explain man;y of the inconsist

encies of speeds and strain patterns which have been observed. Fracture

speeds ranging from 1,800 to 7,550 have been measured, with seventy-.five

per cent of the speeds within the range of 2,100 to 3,900 f'ps. Although a

number of inconsistencies in the speed measurements have been noted, the

speed measured from crack detectors has been ~airly constant across the

plate 0 However, no definite speed versus strain, or speed yersus tempera

ture relationship is apparent as yet.

In the wide plate tests, the fracture appearance in many specimens

has varied from extremely smooth to coarse, but no correlation has been

observed between the fracture appearance and the measured speed or strain

response. Studies show that the smooth texture is accompanied by negligible

reduction in plate thickness while the very coarse texture is generally

associated with reductions in plate thickness of one to two per cent.

The brittle fracture of a pull plate with no artificial stress

concentration is reported. This plate failed at room temperature, in a

brittle manner, and at an average stress of 32 ksi (eighty-six per cent of

the original yield strength).

BIBLIOGRAPHY

1. Wilson, W. M., Hechtman, R. A., and Bruckner, W. H., "Cleavage Fractures of Ship Plates.," Univ. of ill. Eng .. Exp. Station Bull. No. 388, 95 pp., (1951) .

2. Feely, F. J., Jr., Hrtko, D., Kleppe, S. Ro, and Northup, M. S., "Report on Brittle Fracture Studies," The Welding Journal, 33 (2), Res. Suppl., 99-s to lll-s, (1954). -

3. Feely, F. J., Jr., Northup, M. S., Kleppe, S. R., and. Gensamer, M., "Studies on the Brittle Failure of Tankage Steel Plates,n The Welding Journal, 34 (12), Res. Suppl., 596-s to 607-s (1955). -

4. Hall, W. J., Godden, W. G., and Fettahlioglu, O. A., "Preliminary Studies of Brittle Fracture Propagation in structural Steel," Technical Report for the Ship Structure Committee under the Bureau of Ships, u. S. Navy, Contract NObs 65790, Civil Engineering Studies, Struct. Res. Series No. 123, 'Uni v. of D.l., June 1957.

5. Hall, W. J., Mosborg, R. J., and M:!Donald, V. J., "Brittle Fracture Propagation in Wide Steel Plates, n The Welding Journal, 36 (1), Res. Suppl., l-s to 8-s (1957). -

60 Irwin, G. R., uFracturing and Fracture DynamiCS, n Trans. Am. Soc. Metals, 4OA, po 147 (1948) .. See also Irwin, G. Ro, and Kies, J. A., "Critical Energy Rate Analysis of Fracture Strength, It The Welding Journal, 33 (4), Res. Supplo, 193-s to 198-s (1954).

7.. Orowan, E., "Fundamentals of' Brittle Behavior of' Metals," Symposium on Fatigue and Fracture of Metals, Wiley, New York, 1952, p. 139.

80 Wells, A. A., liThe Brittle Fracture Strengths of Welded Steel Plates, n

Paper No. 6 at the Meetings of' the Institution of Naval Architects in London, England (M:1rCh 22, 1956) ..

9. Robertson, T. S., "Propagation of Brittle Fracture in steel, tt Journal Iron and steel Institute, Vol. 175, 1953, p. 361.

100 Lazar, R., "Studies of' Brittle Fracture Propagation in Six Foot Wide Structural Steel Plates," M.S. Thesis submitted to the Graduate College, University of illinois, (1957).

TEST (FIG.) PIATE DESIGNATION ANDmTE OF TEST

TABLE 1 OurLINE OF TEffrS

INITIAL LOAD

(KIPS)

srRESS ON NEr SEr!TION

(KSI)

AVERAGE TEMP. (OF. )

REMARKS

The tests w'ere conducted on six foot wide specimens of rinnned steel in a 3,000 ,000 lb hydraulic testing machine. The test piece is an insert 3/4 x 54 x 72 in. welded to one inch pull plates to give a specin~n six feet wide by 18 feet long in plan dimension (exclusive of the pull heads). Following the first fracture test on a given specimen, the .fracture is generally cut out and the remaining portion of the insert (32 in. x 72 in.) used for a second test. The former size of insert is designated by an (A), the latter by a (B) in the remarks column. Notch length I in. Dimensions as noted in Section 7 of text.

12

13 (5)

14 (6)

15 (7)

16

17 (8)

ZlFl-l 11-29-55

ZlFl-2 12-7-55

Z2Dl-1 1-10-56

Z2ffi-2 1-19-56

Z2D2-Impact 2 3-20-56

Z2D2-Impact 1 3-20-56

1065.0

1065·0

96000

960.0

990.0

990.0

20.0

20.0

18.0

18.0

18·5

18·5

-10

0

-8

-5

Room temp. (approx. 71~)

Room temp. (approx. 74-)

(A) Complete fracture. Record lost.

(B) Complete fractQ~e. Good record.

(A) Complete fracture. Record extremely poor; considerable noise.

(B) Complete fracture. Fair record.

(A) Final load -- 990.0 kips. No record obtained. Submerged crack 1/2 in. long.

(A) Final load -- 990.0 kips. Good record. Crack 3/8 in. long on cn,st side and l/e in. :~_uX)g on ,·rest side.

\..N --~

TEST (FIG.)

18 (9)

PLATE DESIGNATION AND DATE OF TEST

Z2D2-1 3-28-56

INTrIAL LOAD

(KIPS)

990.0

TABlE 1 (Continued)

ffi'RESS ON NEl' SEJTION

(KSI)

18·5

AVERAGE TEMP. (oF. )

-t8

REMARKS

(A) Final load -- 990.0 kips. Good record. Submerged crack 2 in. long. Essentially a striking test at low temperature.

Notch length changed from 1 in. to 1 1/8 in. Dimensions as noted in Section 7 of the text.

19 (10) Z2D2-2 1070.0 20·5 -7 (A) Complete fracture. 4-20-56 Good record.

20 Z2D2-3 960.0 18.0 0 (B) Complete fracture. 4-30-56 Record lost. Evi-

dence of branching at center of plate.

21 (11) ZlCI-Impact 960.0 18.0 Room temp. (A) Final load -- 960.0 6-14-56 (approx. 85) kips. Good record.

No submerged cracks.

22 (12) ZlC1-1 960.0 18.0 -10 (A) Complete fracture. 6-14-56 Good record.

23 (13) ZlCl-2 960.0 18.0 -11 (B) Complete fracture. 6-25-56 Good record, except

part ",as lost. ~ m

TEST (FIG.)

24 (14)

25 (15)

PlATE DESIGNATION AND DATE OF TFSr

ZlC2-1 8-1-56

ZlC2-2 8-14-56

INITIAL LOAD

(KIPS)

960.0

960.0

TABLE 1 (Continued)

srRESS ON NEI' SEr!TION

(KSI)

18.0

18.0

AVERAGE TEMP. (oF. )

5

2

REMARKS

(A) Complete fracture. Record quality excellent,' validity questionable.

(B) Complete fracture. Good record except part was lost. Duplicate test of ZlCl-2.

The following series of four tests were conducted on six ft. w~de semi-killed steel specimens with the same notch dimensions as above. No instrumentation. Modification of gas operated piston device made here (See Section 1 of text).

26 (2)

21 (2)

28 (2)

29 (2)

X2El-l 9-11-56

X2E1-2 9-11-56

X2El-3 9-14-56

X2E1-4 9-20-56

890.0

1050.0

945.0

890.0

11·0 -1

20.0 5

18.0 -4

11·0 -2

(A) Final load -- 890.0 kips. No submerged cracks.

(A) Complete fracture.

(B) Complete fracture.

Plate X2El-3 (previous test) was cut in half to obtain 16 in. insert. Complete fracture.

\,J-l \0

TEST (FIG.) PIATE DESIGNATION ANDMTE OF TESl'

mrrIAL LOAD

(KIPS)

TABLE 1 (Continued)

srRESS ON NEI' SOOTION

(KSI)

AVERAGE TEMP.

- (OF.)

Instrumented tests resumed on six foot wide rimmed steel specimens.

30 (16)

31 (17)

32 (18)

Z2C2-Impact 10-25-56

Z2C2-1 10-25-56

Z2C2-2 11-15-56

960.0

960.0

960.0

18.0

18.0

18.0

Room temp. (approx. 78)

-3

-1

REMARKS

(A) Final load - - 960.0 kips. Good record. No sub~rged cracks.

(A) Complete fracture. Good record.

(B) Prestrained specimen. - Complete fracture ~:' Good rec ord .

.ro

41

TABLE 2 TENSILE AND CHARPY mTA FOR PULL PIATE STEEL

A285 Grade C Flange steel Tensile and Charpy Specimens were cut from mid-width of plate adjacent to fracture

(a) Tensile Data (0.505 in. dia. round test coupon)

Yield strength, Lower (ksi) M3.ximum Strength (ks i) Elongation in 2 in. (per cent) Reduction in Area (per cent) Strain at beginning of, strain

hardening (€sh) in. lin.

(b) Charpy V-Notch 1)3.ta

Avg. of 2 Specimens Parallel to direction of rolling (Vertical)

32.2 65.2 38 56

0.008

One Spec imen Transverse to Direction o,r rolling

30.2 64.6 36 51

0.005

Spec imen Axis parallel to direction of rolling and transverse to fracture. V-Notch axis perpendicular to plate surface.

Temperature

+196 +190 +180 +160 +120 +100 482 +58 +4D +20 ·.··;:0 -40

Absorbed Energy

48 46 44,47 31,35,40 24,25,26 18,18,20 15,15,16 11,12,12 7,8,8 5,5,6 4,5',Q,7 4,4,4

cb PULL HEAD

j.- 6'--

PULL PLATE

1M THICK

INSERT SPECIMEN

3/4" THICK

PULL PLATE I" THI~K

PULL HEAD

9

J 1

SIX-FOOT WIDE SPECIMEN IN 3,000,000 - LB. MACHINE LINE DIAGRAM OF PLATE SPECIMEN

FIG. I

CD -l

~ LL.

>-(!)

cr w z w a w CD cr 0 (f) CD <t

40

30

20

10

o -30

I ;.--~

I / I : /0 ~

~ 0

yf0

f

o +30 +60 +90 +120

TEMPERATURE 0 F

CHARPY V-NOTCH IMPACT RESULTS FOR RIMMED STEEL

TENSILE TEST DATA FOR LUKENS RIMMED STEEL

HEAT NO. 16445 DIRECTION YIELD ULTIMATE ELONGATION REDUCTION

OF ROLLING STRENGTH STRENGTH IN 2 IN. OF AREA KSI KSI 0/0 0/0

PARALLEL 34.7 68.1 36 58

NORMAL 35.2 68.7 31 52

CHECK ANALYSIS OF LUKENS RIMMED STEEL

HEAT NO. 16445

C Mn P S Si CU Cr NI AI

0.18 0.42 0.013 0.031 0.02 0.23 0.07 0.14 0.003

TYPICAL TEST SETUP AND PROPERTIES OF RIMMED STEEL

TEST 26-

TEST 28-

TEST 29-

FIG. 2

FRACTURE PATHS - SEMI-KILLED STEEL

m 120 ...J

l-LL.

80 >-(!) a:: UJ :z UJ

Cl 40 UJ ro a:: 0 en ro

) . /: ~

~ :/

-~ 1_· ~ <{

0 -30 o +30 +60 +90

TEMPERATURE of

CHARPY V-NOTCH IMPACT RESULTS FOR SEMI-KILLED STEEL

DIRECTION

OF ROLLING

PARALLEL

NORMAL

C

0.20

Mn

0.76

TENSILE TEST DATA FOR US S SEMI-KILLED STEEL

HEAT NO. 64M487

YIELD ULTIMATE ELONGATION

STRENGTH STRENGTH IN 2 IN.

KSI .KSI %

34.9 66.7 39

34.3 60.1 39

CHECK ANALYSIS OF US S SEMI-KILLED STEEL

HEAT NO. 64 M 487

P

0.019

S

0.040

SI

0.03

Cu

0.04

Cr

0.02

Ni

0.16

REDUCTION

OF AREA %

65

59

AI

0.002

- TEST 27

FRACTURE PATHS AND PROPERTIES OF SEMI·KILLED STEEL

y

'3 '6

, 2 , 5

Y

WEST SIDE

TEST 15

~- DIRECTION OF FRACTURE

NO. I

2

3

4

5

~ 7 8

NOTE:

x in

6.0

6.0

6.0

18.0

IB.O

IB.O ---36.0

66.0

THIS

USED

y TEMP. AT in TIME OF TEST

-1.0 -3.B

-7.0 -2.3

5.0 -7.0

-1.0 -2.0

-7.0 -3.2

5.0 -9.3 -1.0 - 3.7

-1.0 -5.6

THERMOCOUPLE LAYOUT

FOR TESTS 12 -18

THERMOCOUPLE LOCATIONS AND TEMPERATURE - TEST 15

NO. X Y TEMP. AT in in TIME OF TEST

I 6.0 4.0 -13.8

TEST 23 2 6.0 -4.0 -12.0

3 21.0 4.0 -11.3

4 21.0 -4.0 -10.0

l "I -=- ~ '~ ____ '_" ___ ~-=: 5 36.0 4.0 -10.8

-X 6 36.0 -4.0 -11.0

I ' 2 • 4 ' 6 ' 8 '10 7 51.0 4,0 -10.6

8 51.0 -4.0 -lOA

I

I

DIRECTION OF __ 9 66.0 4.0 -13.0 FRACTURE 10 66.0 -4.0 -9.B

WEST SIDE NOTE: THIS THERMOCOUPLE

USED FOR TESTS

THERMOCOUPLE LOCATIONS AND TEMPERATURE - TEST 23

r----i-_ TEST 24 - ..... 5 I ------

.1 TEST 25

--~---- -----~-----~-----I

I O~--

...... -THERM. 7-3.1 in.BELOWCRACK ----

. TEST 15

r-~ _ - - - I-- ------1 )J--5_ '{ / ----I \ I

W ,) a:: TEST 23 THERM.7 - 0.4 in. BELOW CRACK

LAYOUT

19 - 32

~ \ I -,O------------=~_~'------T-~~~\.r~----~-------r------+------+------+-----~ ~ -15' ~ / - ----

_201~ ____ ~~-~J~--~In_--~~-_.~T,H-ER-M-.-6-J=~4-in-B-EL~0~IW_C_R_A_C~K~ ____ ~ ____ ~ -l .:'" rES TIME OF FRACTURE

o 1.0 2.0 3.0 4.0 5.0 6.0 7.0 B.O 9.0 TIME- MINUTES

TYPICAL TEMPERATURE TRACES AT TIME OF TEST

FIG. 3 THERMOCOUPLE LOCATIONS AND TYPICAL

TEMPERATURE TRACES AT TIME OF TEST

SIGNAL 4

SIGNAL 5

SIGNAL 6

SIGNAL 7

SIGNAL 8

SIGNAL 9'1

SWEEP TRIGGER

NOTES:

SINGLE BEAM C.R.O.

NOTE B •

------: /

TRACES I TO 4

TRACES 5 TO 8

CAMERA

35mm

NOTE A

CAMERA

35 mm

NOTE A

CAMERA

35 mm ~ TRACE

r::=- ~TIMEBA~E 9SIGNALS N~T:: CHANNELS

'--------. UNBLANKING SIGNALS J I TO 8 (NOTE C)

B. UNIT MODIFIED TO ALLOW C. ALL HORIZONTAL

A. CAMERA SHUTTERS MANUALLY OPERATED

ONE SWEEP WHEN DEFLECTION PLATES TRIGGERED. MUST BE DRIVEN BY A COMMON MANUALLY RESET BEFORE AMPLIFIER. PRIOR TO AND FOLLOWING

TEST. RETRIGGERING.

BLOCK DIAGRAM OF RECORDING EQUIPMENT

~ TRIGGER SIGNAL TO SWEEP GENERATOR

THYRATRON

a:: o f~

GEN ER AL VIEW OF RECORDIN GINS TRUME NTATION

~r----7--~L--7~--~~~L-~~-r--~~~--~~--~

MANUAL TRIGGER

TRrGGER ,..- ~-- -TRIGGER SHORTED

{

I FOIL I FOR CALIBRATION

TRIGGERING LL' DEVICES \.lSW~

SR4 A9 3V

-II +

TRIGGER CIRCUIT

a::

z o ~ <t a:: CD ::J <t U

3V DC

GAGE CIRCUITS

DEI DET DET DET A B C D

CAL. CAL. CAL. CAL. A B C D

-1=-

4-0

-----.J -.l CRACK DETECTOR CIRCUITS

FIG. 4 INPUT CIRCUITS AND RECORDING INSTRUMENTATION

UTPUT

Y

733/8" ====i r-------------------~~------~I ~~~~~-~~~1--,-1-...,

ZIFI-2

16"

~f~ (f~A B (4) C 0 16' E -L _ -:L - - - "- - - -~-<: - X r; Jfit='.I -------r----~'::.---------=t=------~~---------7---

1/ I 212 I

32"

v

TEST CONDITIONS STATIC STRAIN GAGES DYNAM I C STRAIN GAGES

AVERAGE NO. ORIEN - X Y INITIAL ORlEN- X Y Yc INITIAL

STRESS 20 KSI TATION in. in. STRAIN NO.

TATION in. in. in. STRAIN

TEMPERATURE = O°F 10 V +3.5 +1.0 +860 I V 12.0 +1.0 +0.7 + 630

II V + 11.5 +1.0 +680 2 V 35.5 +1.0 +2.7 +715 THEORETICAL IMPACT = 1200 FT LB 12 V +36.0 +1.0 +720 3 V 60.0 +1.0 +3.0 + 660

13 V +59.5 +1.0 +660 4 V 35.5 +1.0 +2.7 + 720

14 V + 3.5 +1.0 +700 o GAGES ON EAST FACE 15 V + 11.5 +1.0 +570 t:) GAGES ON WEST FACE 16 V +59.5 +1.0 +650

5000

NOTE : DETECTORS BROKE AS IND ICATED BY

2500 VERTICAL DASHED

rrCD @H' 4 " LINES II ,i; II II , ,

::t: 2000 I! : : t.) :' i \ z a,-. I 1\ I

~ W I /r® ::t: t.) f500 I \ z I

\ i ! I 0

I

a:: I i i I t.) I ) l I ,-::E : j \ f \ 1 1000 I I

i ~ 1~~ :--z \ I <i .1i ~ ~-- ...... -11 /1:" a:: F':"<~ ',,?, " .J \ - / ' "\ I, .... ._--, ... ,:.

~\ " \ \ I )< __ .~!'J t (f) 500 , ----\ ---\-- --,-~ J \ / "

jJ 0

I\. .

A f3 IC 10

II I I

- 5000

: 0.5 1.0 1.5 2.0 2.5 3D 3.5

TIME - MILLISECONDS

FIG. 5 INSTRUMENTATION AND RECORD TEST

DETECTORS

X NO. SPEED

in. A +12.5 B +24.5

3750

3400 C +36.5

0 +48.5 3450

E +60.5

4.0

13

TEST CONDITIONS

AVERAGE STRESS = IB.O K S I

TEMPERATURE = - BO F THEORETICAL IMPACT = 1200 FT LB

o GAGES ON EAST FACE () GAGES ON WEST FACE

2000

::x:: 1500 (,)

~ "-en w ::x:: (,) 1000 z (5 0:: U

i I

Y

~733/B"--------I Ir-- I

" ," " I

Z2DI-1

CD T A BAC D;tt @ 122 134

fC---"-~-i~--------i------ --------" --r-=- ---- --, - - . - - - .- "---

_ 3 .... " 0

'4) \1.9) \!§!

WEST FACE

.' vA

TT I

16"

1 IX

5 4"

I

STATIC STRAIN GAGES DYNAMIC STRAIN GAGES

NO. ORIEN- X Y INITAL TATION in. in. STRAIN

NO. ORIEN - X Y Yc INITIAL TAT ION in. in. STRAIN In.

10 V 1.0 +1.0 +1340 I V 36.0 +6.0 '+1.5 +160

II V 3.5 ... 1.0 +570 2 V 36.0 + 1.0 +1.5 +300

12 V 35.5 ... 1.0 +320 3 V 36.0 -4.0 +1.5 +450

13 V 59.5 +1.0 ~460 4 V 60.0 + 1.0 +1.4 +480

14 V 3.5 +1.0 +1120

15 V 35.5 +1.0 ... 770 16 V 59.5 ... 1.0 1"790

II

i I /@

~ l /® i (\ II r.... I

'-/ I )~/ \ /

Ii '\ 1\ J ' r, ; I {\ I i I

l!

500 Z <i 0:: ~ (f)

0 ~~ ~\ 1\ 'J !\j

i'V \ / V

j ~/l rv ~I

~ ( \ I

-500

-1000 o

\\ V I

Inl ~'l I t i I\!\

IA ""\ ,B) ~ ,~f \ ~ ~ ~ I ~' I j( : I I I l: : I i

0.5 LO L5 ~O ~5

TIME-MILLISECONDS

FIG. 6 INSTRUMENTATION AND RECORD

j ! l~ j " {

V 3.0 3.5 4.0

TEST

DETECTORS

NO. X

SPEED in.

A 12-5

B 24.5 3700

C 36.5 2850

D 48.5 3450

E 60.5 3250

14

TEST CONDITIONS

AVERAGE STRESS = 18K S I

TEMPERATURE = - 50 F

THEORETICAL IMPACT = 1200 FT LB

o GAGES ON EAST FACE C' GAGES ON WEST FACE

FIG. 7

:::t: (.)

z

" (/) LLI :::t: (.)

Z o a:: (.)

:I I

Z <l a: .... (/)

Y

I

73 3/~

.1 Z2DI-2

r

T • B J D ~ 16"

~~-+-==+----~-----~+--:~4 =----<" -Lx

I

NO.

10

II

STATIC

ORIEN-TATION

V

V

(6 3 7' 32" - \!..1

WEST FACE I ."

I v

STRAIN GAGES DYNAMIC STRAIN GAGES x Y INITIAL in. in. STRAIN 3.5 +1 +800 3.5 +1 +1110

CD

A B C

NO. ORIEN- x Y Yc INITIAL TATION In. in. In. STRAIN

I V 35.5 +1 -0.6 + 640 2 V 36.0 +1 -0.6 + 490

3 V 36.0 -4 -0.6 .. 780

4 V 59.5 +1 +0.9 .. 660 5 V 60.0 +1 +0.9 .. 670 6 V 3!s.f5 +1 -0.6 + 540 7 V 59.5 +1 +0.9 .. 510

I I j NOTE: DETECTORS BROKE

o

AS INDICATED BY -

VERTICAL DASHED

LINES.

E 0~--~-r--~~-r--~~--~~~----4-----~

J I J J I I

I I I

i : : o 0.5 1.0 1.5 2.0 2.5

TIME - MILLISECONDS

INSTRUMENTAT10N AND RECORD TEST

DETECTORS

X NO.

in. SPEED

A +12'.5 .8 +24.5 3050

C +36.5 2800

0 +48.5 2800

E +60.5 2400

15

1~~~'-------73 3/8"~'-------------------------I~ ___ , ____________ J~\~ ______________ ,;.,~I

ET CD®. -?-~~-

([®

Z2D2-IMPACT-I II 27" I

I I ~X54"

I

(@ (@ ------ 0 -- --- --~---- I

@ (j)

93"

® f--- - --- I ---- - - ---- --I-~-

A

v

TEST CONDITIONS STATIC STRAIN GAGES DYNAMIC STRAIN GAGES AVERAGE OR/EN- X Y INITIAL STRESS = 18.5 KSI NO. TATION in. in. STRAIN

TEMPERATURE =74°F 10 V 36.4 0 1'600 II V 7.0 0 1'680

THEORETICAL 12 V 36.4 0 -t630 IMPACT =1200 FT LB 13 V 66.4 0 +S80


CD

-150 "'='" I ,

Z :I: 0 U(i)

~ ~ -170~ ....... _. -'-_~_

OR/EN- X Y INITIAL NO.

TATION in in. STRAIN I V 3 0 +820

2 H 3.5 0 -ISO

3 V S -4 .... 610 4 H S.S -4 -170

S V 7 0 .... 640

6 H 7.S 0 -ISO 7 V 66.4 0 .... 480 9 V 18.7 -93 +500

®

rl:"O ~ @_ o 640Li~--~~~~======~====~======~=====i======~====~~--~ ex: ~ Z-250

~o

I~ ZW <ig: o:::~ .... 0 (/)U

/~~~~- ---~ -15 0 k-~----lW--I--+---+---+----+---+---+----=-t-----l

480~ ____ ~ __ ~=-~ ____ ~ ______ ~~CV=7 __ ~ ______ ~ ____ ~ ____ ~ ____ ~ ~ ~~-----~-~----~------i------1------i------i-

® 500 ""V

o 1.0 2.0 3.0 4]) 5.0 6.0 7.0 8.0

TIME - MILLISECONDS

FIG. 8 INSTRUMENTATION AND RECORD TEST 17

ET

y

Jr--. --733/8" ------+ij It -.J'

Z202-1

A B C D E

C?-~I -~- +--ttl~ct @ @ @

:;0.,-0 --- -----0 -- - -- --tr-C:

Q~ ~~ t@

WEST FACE

® ®

D 1[':4' 104"

--- I -- -- ---- 1--- --c-

TEST CONDITIONS STATIC STRAIN GAGES DYNAMIC STRAIN GAGES

AVERAGE STESS = 18.5 KSI

TE MPERATURE =+ 8°F


o GAGES ON EAST FACE C:: GAGES ON WEST FACE

Z :x: 0 u U5 ~ z

w

510

570

"' '1+250 - 200 C/)

W :x: u fo z (5

! a: 1-250 530 U

::=E z 52

I C/) C/)

Z w a:

<t a.. 540 0: ::=E t- O en U

400

430

NO. OR IEN- X Y INITIAL TATION in. in. STRAIN

10 V 6.0 -II +470

II V 36.0 -II +590

12 v 66.0 -II +590 13 V 6.0 -II +620

14 V 36.0 -II +630

15 V 66.0 -II +680

.,r-/'J{

J ~~ CD

®

Q)

-- @

@

@

®

o 1.0 2.0 3.0 4.0

TIME -MILLISECONDS


NO. ORIEN- X Y INITIAL TATION in. in. STRAIN

I V 3.0 0 +510 2 V 36.5 0 +570 3 H 37.0 0 -200 4 V 64.2 0 +530 5 V 70.2 0 +540

8 V 18.7 -104 +400 9 V 54.7 -104 +430

-

5.0

TEST 18

• ( ~ ( .. C .. .. c a

1

y

~------------------~~

73318'~

TEST CON OITIONS

AVERAGE STRESS ,. 20.5 KSI

TEMPERATURE --7 e F

THEORETICA L IMPACT . 1200 FT LB

o GAGES ON EAST FACE

() GAGES ON WEST FACE

::J: U Z

~ W ::J: U Z

o a: u ~ I

Z

<x: 0::: t(J)

FIG. 10

~-----.--

Z2.D2 2 I 16"

EAST FACE

® ® - t-- _. - ~ ." -+

" v


ORIEN - X Y Yc INITIAL NO. TATION in. in. in. STRAIN NO.

ORIEN- X Y INITIAL TAT ION in. in. STRAIN

10 V 1'7.0 -11.0 + 700 I H 36.0 0 -toO.6 -340 II V +36.S -11.0 + 620 2 V 36~ 0 +0.6 +470 12 V +66.4 -11.0 + 590 3 H 60.!5 0 0.0 -30

13 V + 6.0 0 +S80 4 V 61.0 0 0.0 +550 14 V +70.4 0 +870 5 V 36.5 0 1'0.6 +940 IS V + 7.0 -11.0 +710 8 V .54.7 ~04. 0.0 +490 16 V +36.S -11.0 +670 9 V 18.7 -104. -0.6 +490 17 V +66.4 -11.0 +710

2500

1500

I I I ~\ NOTE:DETECTORS BROKE

20 0 0 I-------+--jl-I,I\ --+: T-, +------t- AS IN D I CA TED 8 Y -

L ~: VERTIcAL DASHED

)'\ :\ :' ,I "

LINES

/( " :' I ::

) \ I'

I Ill:

500 :--.~ ___ -- __ _ ~V \

I

500 F=-=~t>~ ~ f-<® 0./ ~-........ ~j--...-,~"----,~ ~AIB Ie IDEI' V---" :: : : :;r-~ 1'-----""

I I I I I : I I : I

-500 0 0·5 1·0 1·5 2·0 2·5 3'0

TIME- MILLISECONDS

INSTRUMENTATION AND RECORD TEST

DETECTORS

X SPEED NO.

in. A +10.5

B +19.5 3750

C +37.5 3800

0 +54.0 3450 I

E +69.5

19

lY I \-. ----------731/4"

.--------~-------------------~ ~\\\\\\\\\\\\\\\\\

ZICI-IMPACT -rr (161 115, 1141 I I

::J'---D@ ------~t0--------/~--. -, r I lP:® @ ,I,,, I 54"

E'~:l ·;-C2~-------------------c ! J x

~~ (~)

EAST FACE

'\\'\\\\\\\

I


AVERAGE NO. ORIEN- X Y INITAL ORIEN- X Y INITIAL

STRESS = IS.OKSI TATION in. in. S:rRAIN NO. TATION in. in. STRAIN

10 V 61.25 +11 +630 V 4.0 +3 '+640 TEMPERATURE = S5° F II V 36.0 +11 +560 2 H 4.5 +3 +160

THEORETICAL 12 H 35.75 +10 -160 3 V 5.0 0 -170 IMPACT = 1200 FT LB 13 v 13.25 +11 +620 4 H 5.5 0 +620

14 V .61.25 +11 +420 5 V 4.0 -3 -150

15 V 36.0 +11 1'540 6 H 4.5 -3 +440

0 GAGES ON EAST FACE 16 v 13.25 +11 +570 7 V 9.0 0 +420

() GAGES ON WEST FACE 8 H 9.5 0 +410 9 V 5.0 0 +360

Q) 640

® 160 ---~

-170 @ - -.,... "' ....

Z :x: 2 ....... @ u(/) 620 ZZ "'-" -LIJ

~r" ® ~ 0 -150

0 ~ -250 -0

@ ::1:-I~

ZLIJ 440

-I----' -0:: <ta. 0::::1: 1-0 CJ)u (f)

420

I ....

@ 410

'\oJ'

®

------

360

0 1.0 2.0 3.0 4.0 5.0

TIME -MilliSECONDS

FIG. II INSTRUMENTATION AND RECORD TEST 21

yjl------73 1/4" I II....--------v"'-----

ZICI-I

T A B c

L ~-- ---t----------- 1 - ~-r =~f---=----T ---- ;~ 2

TEST CONDITIONS AVERAGE STRESS = 18 KSI

TEMPERATURE = -10 0 F



(; GAGES ON WEST FACE

FIG. 12

:L: U Z

"C/) LIJ :L: U Z o a: 52 ~

I z <i 0:: l(/)

WEST FACE

® -.------- I

1\ v

STATIC STRAIN GAGES

x Y in. in.

10 V 12.0 0

II V 36.0 0

12 H 37.5 -1.0

13 V 60.0 0

14 V 12.0 0 IS V 36.0 0

16 V 60.0 0

INITIAL STRAIN

+630

-1-560

-160

+620

+420

+540 +570

® 1000~

X

/~ I I I \

I I I \

1.0

® 1--

DYNAMIC STRAIN GAGES

NO ORIEN• TATION

x Y in. in.

Yc INITIAL in. STRAIN

I V

2 D 3 H

4 V

lS H 8 V 9 V

37.0 0 +3.5 + 640

37.lS "O.S +3.5 + 160

~7.s 0 +3.5 -170 61.0 0 +3.5 + 620 61.5 0 +3.5 - ISO

18.6 -104 . '1'2.4 + 42lS S4.6 -104 '1'3.5 + 390

NOTE: DETECTORS BROKE

/.5

AS INDICATED BY VERTICAL DASHED LINES.

2.0 2.5

TIME - MILLISECONDS

INSTRUMENTATION AND RECORD TEST

DETECTORS

NO_

A B

c D

E

22

X in.

12.5 24.5

36.5 48.5

60.5

SPEED

3300

Y

t 731/41~

II rv- ~i

I

TEST CONDITIONS STATIC STRAIN GAGES DYNAMIC STRAIN GAGES AVERAGE ORIEN- X Y INITIAL

NO. ORIEN - X Y Yc STRESS : 18 KSI

NO. TATION in. in. STRAIN TATION in. in. in.

TEMPERATURE :, -II 0 F 10 V 14.5 0 +620 1 V 8.0 0 0.3

II V 35.5 0 +660 2 V 15.0 0 0.7 THEORETICAL 12 V 56.5 0 +630 3 V 22.0 0 1.3 IMPACT = 1200 FT LB 13 V 14.5 0 +530 4 V 29.0 0 2.2

14 V 35.5 0 +530 5 V 36.0 0 3.0 15 V 56.5 0 +570 6 V 43.0 0 3.4

7 V 0 3.5 30.0 o GAGES ON EAST FACE 8 V 37.0 0 3.5 ':) GAGES ON WEST FACE 9 V 64.0 0 3.5

I U ~ '(J) W I U Z o a:: u ~

I z ;;X a: .... (/)

1500r------r------H---~~~--~------4_----_4------4_----~

/\/@C;; ®I\ ® { \ /\ (/ /

looor-----+-----+/~-~il~4h~41--~----_+----~~----+_--~

~5' !0.'/: \ .,y. \ /1 \

t=;;;S;;::::1;_ ~- -:: - . - )< A 500~----_r~~~r+~vL+H--+_~~----4_----_4------4_----~

",~~ \ I I I ~tt::r-=~ _/' -__ --~

[\--\"-r-----r-- -t------~ 0r-----_r------r-----~q_~~------4_----_4------4_----~

'v'-'~_<::::~ -::::==::~. ~~,

-500r-----_r------r-----1-----~------4_----_+------4_----~

-1000 0~----0~.~5------1.~0----~1.~5-----2~.-0-----2J.-5-----3~.0------3~.5----~

TIME - MILLISECONDS

INITIAL STRAIN .+ 6/0 + 820

+ 620

+630

+670 +670

+640 +630

+620


y

r--------73 114"'-------------..J

II -----vI' ZIC2-1

1 CD @) ® --- -1------ -1- - -- - -1----- 16" T

~. ® ® ® -1x -~=--.~-:.---""-=_=._'=III----_==_=_==__~~.........c

@ @ @ (l3) @ t~

-I- :-1- -t- --@ ® ®

54"

WEST FACE ~ I vA

TEST CONDITIONS STATIC STRAIN GAGES DYNAMIC STRAIN GAGES AVERAGE STRESS = 18 KSI

TEMPERATURE = + 5° F

THEORETICAL IMPACT = 1200 FT L B


\~~ GAGES ON WEST FACE

10RIEN-NO. TATION '

10 I v II I v 12 I V

13 I V

14 I V

15 I V

'I

I I

x y INITIAL in. in. STRAIN

12.5 0 +480 3S.!i 0 +470 SO.!i 0 +490 12.5 0 +S40

3S.5 I 0 "'S30 SO.5 0 +610

NO. ORIEN - 1< y Yc INITIAL TATION In. in. in. STRAIN

I V 12.0 + 8.0 ' +O.!i +570

2 V 12_0 0+0.5 +470

3 V 12.0 -16.0 +O.!i +570

4 V 36.0 +8.0 -0.3 +550 5 V 36.0 o -0.3 +480

6 V 36.0 -16.0 -0.3 +540 7 V 60.0 + 8.0 -0.1 +555 8 V 60.0 o -0.1 +500 9 V 60.0 -16.0 -0.1 +540

200Ga------r---~/+·T_~--+_--_+----~---~--~--~ ® / \~

Z <t 0:: l(/)

r-.. / : -- ----, ---"j :

1500; \ I

\/----r---_ " '/

t :' ®', \ v-(v l : y-.. /1

1000: ~: f ~/ .--I . \~ ..... ,' ,t.._ --" ....

I ;t-.) _-_. ~ I 500 ~t::~( . ---~ f

\ I-,,\:.t-\j§J -- -i;

./', /, ,~-~--- r-- '-v'

- , -,,---------/' ~--_/' \ ...... -------

@ __ <~<~:::~ .):---___ -_ -_.J'

O------r~~~~--_+---=+_--_4----~-----~----~ -", CD ,~\

\~---- I \ -- --------"_,,J" \\, ..... , ... '-,_ .... __ ... _____ " .... _ ....... ___ ............. ___ _

-500r------r----~------1_----_+------+_----_+------+_----~

-10000~----~0~5~--~I~.0~----~1.5~--~2~.0~----2~.~5-----=3~.O~--~3~.5~--~

TIME MILLISECONDS


y

Ir--__________ /'--73 114"~

32" ® ® ® ® ® ® ET __ =>---"'-'"I"'---::OI==--::I-=-:..-)=---=1)-::.--==-II-::.-..::.:..:r.::--=u .... .::---=J::.-:..--~-i: -.----X i

@ ® @ I @ (~ @j I~"

WEST FACE

I


AVERAGE STRESS = 18 KSI

TEMPERATURE ::-. + 2° F

TNEORETICAL I M PACT = 1200 FT LB


C GAGES ON WEST FACE

2500

fj) 'I

2000 I U

~ 'I

" ...... " : ' en

w 1500 , , I u Z

I 0 c::

I I , CD : :

LX' ' , / l/

~ 1000 ~

I ~ <l

!-"-<---~ -

1 I

0:: 500 .....

ff)

'-0

NO. ORIEN- X Y INITAL TAT ION in. in. STRAIN

10 v 14.5 0 +610

II V 35.5 0 +590 12 V 56.5 0 +560 13 V 14.5 0 +570 14 V 35.5 0 +610

15 V 56.5 0 +610

(i.,@ " ,;

@) II ',~ il Ii I' , . i

~ !( , ~

" n I. , \ I i I I,

J I

II I I ,I I ) , } ; I I I I

I I J , ' I ' , \ '

I .': ( 1 I / \ ,

I ' ,

... / i / I f'l._ -I I

, I i ~--- .. I .. .' ~ \, --- ---- '---

- ---- -....... -

f--~-C:::::-"'=

----- --- ---::::-::~

NO. ORIEN - X Y Yc INITIAL TATION in. in. in. STRAIN

I V B.O 0 +0.5 + 590

2 V 15.0 0 +0.8 + 610

3 V 22.0 0 +0.7 +610

4 V 29.0 0 +0.7 +560

5 V 36.0 0 +0.9 +600

6 V 43.0 0 + 1.0 +610

7 V 50.0 0 +0.9 + 620

8 V 57.0 0 +0.9 + 610 -9 V 64.0 0 +0.8 + 610

.--.-----:::--:: t;~:-~7- r---~::: ---:.:.-~- -- --' ./ ----/ --- ---------~ "'--,

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

TIME -MILLISECONDS


y !f------------73 114"!..-' --------1

1 'Ir--

Z2C2-IMPACT 11 CD @® Q@ @@ 00 @ Q3) ~ P--~-O-+--I-[}----Or ---01--1-0 _._c= --1 x 1

'r~):7: @', 'i?;:g· @: ~[g'

54 N

EAST FACE

T EST CONDITIONS STATIC STRAIN GAGES DYNAMIC STRAIN

AVERAGE STRESS = 18.0 KSI

TEMPERATURE = 78° F



~ u ~ z " 0 en U5 UJ ~ Z U UJ z

1:"0 0 n:: u i 0 1-250 0 Z 10 0 II U5 ~ en u w z a::

a.. ~ 0 U

Z <{ a:: I-CJ)

NO. ORIEN-TATION

10 V

II V 12 V 13 V 14 V 15 V 16 V 17 V 18 V 19 V

560 .~

560 r--------' i

i i

i

520

,

470

460

i 490

650

I I

I 710

i

o 1.0

X Y INITAL in. in. STRAIN

ORIEN-NO.

TATION 13.3 0 ... 530 I V

25.3 0 +510 2 V

36.3 0 "i-480 3 V

49.3 0 "i-480 4 V

61.3 0 ... 510 5 V

13.3 0 1"640 6 V

25.3 0 +690 7 V 36.3 0 ... 730 B V 49.3 0 +710

61.3 0 't"660

CD ---v-- c- •.• _ o.

.~ ®

~ -

I

@ ~ -

I ! @

® "-"

...... ® -:::.

(J)

®

2.0 3.0 . 4.0 5.0

TIME - MILLISECONDS


X Y in. in. 9.3 0

16.3 0

23.3 0

37.3 0

51.3 0

58.3 0 16.3 0 37.3 0

-=-

--

~ .-

TEST

GAGES

INITIAL

STRAIN +560

+560

+520 +470

+460

"i-490 "i-650.

+710

30

y1 .... ·------73 1/4"

-J' "

Z2C2-1

A B C D E

E.T. @P-~-~~~~F~ Q5 1§ fj) C!:~ ~B ~(~

WEST FACE ,\'

'] .J'

T EST CONDITIONS STATIC STRAIN GAGES DYNAMIC STRAIN GAGES

AVERAGE NO. ORIEN- X Y INITAL NO.

ORIEN- X Y Yc INITIAL

STRESS ::: IB.O KSI TATION in. In. STRAIN TAT ION in. in. in. STRAIN

1 V 15.0 0 +0.1 -t-490 TEMPERATURE = - 3° F

THEORETICAL

10

II

12

v V

V

12.0 0 24.0 0

37.0 0

+510 +480 2 V 22.0 0 +0.1 +460

+480 3 V 36.0 0 +0.9 +470 IMPACT ::: 1200 FT LB 13 V 48.0 0 -t-5/0 4 V 50.0 0 +1.6 +520

14 V 60.0 0 +530 5 V 57.0 0 +1.8 +560

15 V 12.0 0 +660 6 V 64.0 0 +2.3 +1560 o GAGES ON EAST FACE 16 V 24.0 0 +710 7 V 36.0 0 +0.9 +710

17 B V 57.0 0 +1.8 +6150 o GAGES ON WEST FACE V 37.0 0 +730 18 V 48.0 0 +690

FIG. 17

19 V 60.0 0 +640

3500~----+------4-------~---~---41~~~~---~-----~---~

3000~-----+------~------r-----r--~--+-----'-+------~----~

~J i

2500r-----~-----~------r_----_+--!~~4------4-----~----~

J

I. \ I ~@ 2000r-----_+------1_------r_-----r-+-r~~lfi~ ,~~~~~~~~4_--~~

i VI ~V-i !/® J r I'V

1500r----_+------1_------r------r~+---~1I------+_----~-----~

.. il I A 1000~:----_+------1_-----r_----_r¥/~--_7~------+_----~-----~

j"'>J1/ .... i') - _.- -'-'- -- _.- -!---:rr-./ ~ ---------r------~----------./'-),

~oo ._'0 . ._ _ •..••. __ ... __ ,_._ ........ ~

~-'

°0~---~0~.5~-~1~.0~-~1.~5--~2.~0---~2~.~5--~3.~0~-~3.~5--~4.0

TIME -M 1 LLiSECONDS

INSTRUMENTATION AND RECORD TEST 31

DETECTORS

NO. X

SPEED in.

A 12.5

B 24.5 3450 2150

C 36.5

0 48.5 2400 3250

E 60.5

TEST CONDITIONS

AVERAGE STRESS = 18 KSI

TEMPERATURE = -1 0 F


o GAGES ON EAST FACE C GAGES ON WEST FACE

1000

NO.

10

" 12

13 14

15 16

17 18 19

Y

1--------73 1/4''--' ----------~

~-------------~~--------~

WEST FACE I ~~~~~ J


NO. ORIEN - X Y Yc INITIAL TAT ION· in. in. in. STRAIN

ORIEN X Y INITAL TATION in. in. STRAIN

v 12.0 0 +490 1 V 15.0 0 +2.0 +570

V 24.0 0 -+510 2 V 36.0 0 +6.6 +550

v 37.0 0 +550 3 v 50.0 0 +7.2 +550

V 48.0 0 +520 4 V 57.0 0 +7.1 +540

V 60.0 0 +540 5 v 64.0 0 +6.8 +510

V 12.0 0 +550 6 V /5.0 0 +2.0 i'610

V 24.0 0 -+510 7 v 36.0 0 +6.6 + 630

V 37.0 0 +620 8 V 57.0 0 +7.1 + 570

V 48.0 0 +510 V 60.0 0 -+640

~ r @

Cf /\1 j\ ,\

500

II / ~n ~ r-' \ \ .. ~ ~.-I-...I \ .

I (.)

0 ~ ....... en w

\ , ,-

~ 1 t----.... --- -.... ~ ~ ./"'0.. ~

: ~ ... . "-'.\' 17-.----..... ~::::::-:=:-----.-. . ,:",---._..--

\ ~/ '"' ..... -~/ /----.... , . r-:::-"..-=---:J::.~ ;:--:;::--=~/- --- -----~

I (.) Z 0 a:: (.)

~ CfJ 0 I

z 1000 <{ a:::

f'l ~ (~

j l\ /{ I-(f)

500 ~\ / ./ \

~ '\ ' ~ .... ~~

i

o

-500 o

FIG. 18

\ -v \ \ \, \ I

~ \ \ j

'l ~ \ r, .....---.-~ , ' , "--__ 0, . -~~- p-.::;::.;:.- - -, I ..... /~"'--

,}

0.5 1.0 1.5 2.0 2.5 3.0

TIME - MILLISECONDS

INSTRUMENTATION AND RECORD

~ -~ ~

3.5

TEST

DETECTORS

X NO. in. SPEED

A 2.0 3150

B -'2.5 C 24.5 D 36.5 E 48.5 ;

F 605

32

I <.:> ~ '-(f) W I <.:> z 0 a:: <.:> ~ I z <r 0:: I-Cf)

(REFER TO FIG. 13)

T=O.OO 0

T=0.25 0

T= 0.50

EDGE OF PLATE GAGE

5 6 7

.-8 9

O~----------------~--~--~--~--~--~

T=0.65 0 0 0 It)

+

0

T= 0.85 g 0 It)

I

I T= 1.05 0

I T= 1.16 r. v

-- EDGE OF PLATE

5 6

T=1.23 I 0

GAGE

7 8

-9

T= 1.40 I 1 O~--------~~~~~~

I T=1.54 I 0

T=1:68 I I I 0 I

I I T=1.80 I I 0 .

T=2.00 I I 1 0 • I

FIG. 19 STRAIN DISTRIBUTION AT VARIOUS TIMES TEST 23

!)

i ~

EDGE OF PLATE r EDGE OF PLATE

GAGE ( REFER TO FIG. 15) GAGE I 2 3 4 9 I 2 3 4 9

T = 0.00 0

T = 0.20 0

T= 0.90 0 .

I

I T= 1.00

I 0 - .. I T =0.40

::t: 0 c..> ~

" 0 en I.Ll 0 ::t: IC) c..> + z (5

T= 1.65 a::

I c..> T=0.42 0 ~ 0 - I 0 • I

z <t a: 0 I- 0 CJ)

IC)

I

I T= 0.60

0 ""

T=0.65 T=1.77 ,., II

0 -"" .. II .. T: 1.82 I 0 • . T= 2.20 I T= 0.80 a II

0 I

FIG. 20 STRAIN DISTRIBUTION AT VARIOUS TIMES -- TEST 25

EDGE OF PLATE EDGE OF PLATE

GAGE (REFER TO FIG. 17) GAGE

I 2 3 a 7 4 5 a 8 6 7 5 8 8

T = 0.00

0

T = 1.32

0

T = 1.47

T = 2.31

0

0 :I: U ~ '- 0 T = 1.60 C/) w 0 :I: In U + z 6 0 a: u ~ 0

I z ~ a::: 0 .- 0

In en I

T = 1.67

I T = 2.45

0 0

-

T = 2.59

0 T = 2.20

0

FIG. 21 STRAIN DISTRIBUTION AT VARIOUS TIMES -- TEST 31

EDGE OF PLATE EDGE OF PLATE

GAGE (REFER TO FIG. 18) GAGE

156 257 3 458 5 156 2 e 7 3 458 5

T= 0.00

O~-----JL---------~----~--~--~--~

T = 0.97

o f

T = 0.36

O~ ____ ~~ ________ AL ____ -J __ ~ __ ~ __ -4

T = 1.17

~ r

T= 0.46 0

0 I

:::t: Co)

~ ....... 0 CJ') IJ.J 0 :::t: 10 Co) + z

T= 1.26

I 11 t

(5 ex: Co)

~ 0

I T = 0.52 0 Z ~ a:: 00

I .... 0 10 en I

T = 1.44

~ • f

0

T= 1.70

J1 r I • 1

T = 0.65

I 0 I 0

T = 2.00

n f

. I r I o

FIG. 22 STRAIN DISTRIBUTION AT VARIOUS TIMES - TEST 32

w (!)

o w

o

3750 3400

TEST

NO.

NOMINAL TEMP.

STRESS KSI DEGREE F

1-------- ______ ?_2 Q.~ ______________ ~~ 13 20 o

3700 2850 3450 3250

3050 2800 2800 2400

4350 ON EAST FACE f- -2H)o-or,rWtsi-FA~ ]

14 18 -8

15 18 -5

3750 3800 34_~

J

en t-Z I.LI 60 ~ W a: ;:> Cf)

~ w ~ 40

u.. 0

ci z 20 -.J

~ 0 t-

u.. 0 0

~ 0

FIG. 23

3750

2

I--

r---

r----

J (\J

I -

75!0 1--------- --------~

r----~~~Q----- - ... ,

~-----g~~~-- ---- ~ 3900. 26~ 0 4850 365Q -=----,..-- +-- --t-o- --.;

3 4 5

DISTANCE - FEET

6

FRACTURE SPEED MEASUREMENTS

NOTE:

19 20.4 -7

22 18 -10

23 18 -II

24 18 +5

25 18 + 2

31 18 -3

32 18 -I

NOTE: --S PE ED DETECTORS

- - - - - STRAIN GAGE

I 2.5 STRAIN GAGE MEASUREMENTS

~ 2.1 ORACK DETECTOR MEASUREMENTS

n I J - ..

~ <:t It) CD I'- CD I I I I I I (\J r0 ..;t It) CD I'-

i SPEED XIOOO FPS.

MEASURED SPEED DISTRIBUTION

FRACTURE SPEED IN SIX FOOT WIDE STEEL PLATES

z 3: 0 :I: U)

(!)

z c ~ 0 ..J

0 t-

(!)

z c z 0 0-U)

UJ a: a: 0 (,)

-c:

~ :::l..

z <t a: t-en

E~ST FACE)

WEST FACE

STRAIN DETERMINED BY

SR-4 TYPE A-7 GAGE

10,000 EAST FACE~ •

20,800

WEST FACE~ 20,000 I y-"\ I

;/. I 2300 k /' I

SpOO ( I llMMEDIATEL Y / I BEFORE FRACTURE I 18,000 / OF PULL PLATE) I I I I I

6,000 f I

" 16,000

4,000

14,000

2,000 r 1 I __ =-- 12,000

1,000

0

/'- ..... / ......

/ ............ "- LOAD = 1700k /

/ /

1,000

8,000 0

I'oo:r--__ -LO!.?-=~~::>!j

6,000

I'OOO~ ________ . ___ ~~~_D_=U ~~~j I I I I I I I I I 0 I

___ ~ ___ ~_A~=:~:k ] I

'.oo:b I I

--..,j,

06 6 5 4 3 2 I 0 5 4 3 2 PLATE WIDTH (FT) PLATE WIDTH (FT)

FIG. 24 DISTRIBUTION OF STRAIN ACROSS PLATE

VARIOUS LOADS DURING PRESTRAINING TEST

0

FOR

32

TEST 18

TEST 30

·FIG. 25 ,TYPICAL PHOTOGRAPHIC RECORDS FOR IMPACT TESTS

-FIG. 26 PHOTOGRAPHIC RECORDS FOR TEST 23

TEST 15

TEST 19

TEST 32

FIG. 27 TYPICAL CRACK PATH.S

TEST 12

TEST 20

FIG. 28 CRACK PATHS FROM TESTS WITH NO RECORDS

TEST 24

TEST 32

FIG. 29 TYPICAL CRACK TEXTURE AT INITIATION EDGE

Z2D2-1 NObs 65790

18 K51. O°F 1200 FT - La 28 MAR.. -56

FIG. 30 REINITIATION OF FRACTURE FROM PARTLY

SUBMERGED CRACK ... TEST I 8

FIG. 31 BRANCHING OF CRACK NEAR CENTER OF

SPECIMEN TEST 20

ZIFI-2 NObs 65790

ZOKSI- 1200n·L8-(Jf TESTED 7 DEC. J55

h' l:. ;·--'i .. ~.:!~~,~

\ 't' 1· ',' . ;:;}":r¥-':-,, ,

;:

1

t i

I-I

~~ __ -=-4 ____ ._.

Z2DI-NObs G5790,

18 ~Sl 1200fT-LB O· F TESTED 19JAN.'56

FIG. 32 VARIOUS SECO~JDARY CRACKS

TEST 13

TEST 14

TEST 15

FRACTURE PATH

LOWER PORTION OF FRACTURED PULL PLATE SHOWI N G STR AI N LI N ES

FRACTURE SURFACE IN REGION OF INITIATION

TENSILE TEST DATA FOR A 285 GRADE C FLANGE STEEL

YIELD

STRENGTH

KS I

.37.2

ULTIMATE

STRENGTH

K S I

58.3

ELONGATION

IN 2 IN.

31

CHECK ANALYSIS OF A 285 GRADE C FLANGE STEEL

C Mn P S

0.25 0.49 0.016 0.040

FIG. 33 PULL PLATE FRACTURE

STUDIES OF BRITTLE FRACTURE· PROPAGATION IN SIX FOOT … · Complete Fracture Test --A test in...

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Transcript of STUDIES OF BRITTLE FRACTURE· PROPAGATION IN SIX FOOT … · Complete Fracture Test --A test in...