Modeller User Manual_3

Annotating the Model

21

Chapter 3 LUSASFile TypesLUSAS uses a significant number of different file types for a varied range ofpurposes. This diagram shows the manner in which external files link with LUSASand related programs. The file types covered are summarised below.

q Model Files (mdl) are created by LUSAS Modeller and are used to store allmodel definition information.

q Analysis Data Files (dat) are created by LUSAS Modeller during thetabulation phase. They are required by LUSAS Solver in order to perform ananalysis.

q Results Files (mys) are created by the LUSAS Solver and contain all of theanalysis results for access by LUSAS Modeller. Results files are also referredto as plot files.

q Command Files (cmd, vbs, jva) contain a collection of LUSAS Modellercommands so that, when they are replayed, a sequence of operations may becarried out automatically. Command files can be recorded by LUSASModeller or edited directly using a text editor. See also LUSAS ProgrammableInterface.

q Session Files (ses) are created automatically by LUSAS Modeller every timeLUSAS Modeller is run. They contain a record of all commands issuedduring a session.

q Interface Files (dxf, igs, lyp, def, lms) allow graphical structuralinformation to be exchanged between LUSAS Modeller and externalpackages.

q Picture Files (pic) allow the screen contents to be saved in a neutral fileformat. Picture files are used to subsequently display the information or, inconjunction with the expose program, to create files which may be printed orplotted.

q Start-up Files (str) are user-defined files which are created to control theLUSAS Modeller initialisation sequence. They can contain system parameterinformation and/or LUSAS Modeller initialisation commands.

Chapter 3 LUSAS File Types

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Tip. All LUSAS file types assume the default extensions given in brackets. Whenspecifying filenames within LUSAS it is good practice to simply supply the filenamewithout the file extension. LUSAS will then supply the correct extension for the filetype being written which will ensure that existing files are not inadvertentlyoverwritten by specification of the wrong file type.

Model FilesModel files contain all the information regarding the current LUSAS database andsettings. The information is stored in an unformatted binary form and may only beaccessed using LUSAS Modeller. A model file is not saved automatically, LUSASModeller prompts on exit as a reminder to save changes to a model file.

File manipulation is controlled using sub-menu entries below the main File menu,giving access to the following facilities:

q New Prompts to close an existing model file if open, and opens a newmodel file. Model initialisation will delete all feature, attribute and utilitydatasets and re-read any start-up files carrying out any configurationinstructions contained in them.

q Save or Save As The current model may be saved to disk at any time byselection of either the Save option or the Save As... option. Save As allowsspecification of a alternative filename. If Save is used on a new model afilename is required. LUSAS will prompt for confirmation to proceed if anon-standard file extension is entered, or if a file already exists with the givenname.

Note. LUSAS stores all actions carried out during a session in a temporary sessionfile, which is deleted upon exit from the program. To avoid losing work carried outduring the session, the model should be saved to disk before exiting LUSAS.

q Open Previously saved model files may be opened by selecting the requiredmodel file using the File Selector dialog box. LUSAS may prompt forconfirmation before the currently loaded model is overwritten. Files may beopened with read only status to prevent accidental alteration.

q Close Closes the currently open file.Under the UNIX operating system, LUSAS will ensure binary-compatibility of modelfiles across different platforms. Model files may also be prepared such that they canbe accessed on a PC, using the system parameter NOTNAT. Setting this parameterto 1 in the LUSAS start-up file swaps the byte-order when the model is saved.

Analysis Data Files

23

Note. Model files are the only complete and fully upwards compatible form ofmodel storage. Use a compression utility such as PKZIP or gzip to make them assmall as possible before archiving them from disk.

Analysis Data FilesIn order to perform an analysis, the LUSAS model data must be converted to aLUSAS data file. The LUSAS analysis data file has a .dat extension.

Writing the LUSAS data file is controlled using the File > LUSAS Datafilecommands. This produces a data file in readable ASCII text format. If necessary, thefile may be edited with a standard text editor. The format of the analysis data file isdescribed fully in the LUSAS Solver Manual.The following options are available:

ProcessControl over data tabulated is available using four options:

q All itemsq Selected itemsq Visible items Parts of the model can be made invisible when they are formed

into groups.q Selection memory items

Datafile Type

q General analysis should be used for all analysis types except Influenceline analyses.

q Influence Lines produces a data file as above with additional filesdescribing influence line and search area information.

Datafile Options

q Solve now Initiates the LUSAS Solver and solves the datafile. Otherwisea datafile is written but not solved.

q Wait for solution LUSAS Modeller cannot be used while the solution isprogressing when this option is selected.

q Load results Automatically loads the results file over the model filewhen the solution has successfully completed.

q Plot File Configures the LUSAS data file to create a LUSAS resultsdatabase.

q Restart File Configures the LUSAS data file to create a LUSAS restartfile.

q Load output file Loads the output file created during the solution process.


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q Deformed (Geometry) Produces a data file containing the deformedshape from a previously run analysis. To create a data file containing thisinformation a model file and a results file must be loaded and the requireddeformed shape must be displayed. See the Case Study. Tabulating aDeformed Mesh below.

Tip. During the tabulation process LUSAS will report its progress to the LUSASmessage window. If problems are encountered LUSAS will display warnings and/orerror messages in this same window. Such warnings and errors can be caused byinconsistencies in the model data which may produce erroneous analysis data files.These errors should be acted on before continuing with a LUSAS analysis.

Caution. Tabulating a deformed mesh will output the last displayed geometry asthe nodal coordinates, therefore pay special attention to any applied deformationscale factors.

Running a LUSAS Data CheckA LUSAS data check completes the pre-solution stage of a LUSAS analysis only.This is often a useful check on model integrity and applied boundary conditions asmodel summary information is written to the LUSAS output file and a LUSAS plotfile is created.

Specifying LUSAS Output OptionsLUSAS options controlling the information written to the LUSAS output file duringan analysis can be set from within File > Model properties. Options can also be setfrom the command line using the Set Options command. See the ModellerCommand Reference for more details of the options available.

Controlling Results Content of LUSAS Output FileThe results written to the LUSAS output file (not the LUSAS plot file) can becontrolled from the Output dialog, click on the Output button on the LUSAS datafiledialog. It is possible to request nodal and/or Gauss point output as well as turn ondisplacement and reaction output. By default no results are written to the LUSASoutput file.

Case Study. Tabulating a Deformed Mesh

In a buckling analysis, such as the self-weight of a conical roof, it is useful totabulate the deformed mesh of a linear static analysis as the starting point for thebuckling analysis. This can be achieved using the following procedure:

1. Carry out the initial linear analysis.

Results Files

25

2. Load the linear model file containing the pre-processing information from thelinear static analysis using File > Open.

3. Edit any properties and define any additional control datasets required.4. Load the results from the linear analysis using File > Open, change the file

extension to .mys then select the file to open.

5. Display the deformed mesh by adding the Deformed Mesh layer .6. Now tabulate the deformed mesh using File > LUSAS Datafile, and select

Deformed option from the LUSAS Datafile dialog.

Results FilesWhen an analysis is performed by LUSAS Solver it will create a LUSAS results file.The LUSAS results file, or plot file as it is sometimes referred to, has a .mysextension. A PLOT FILE line, requesting that a results file written, is automaticallyadded to a linear analysis data file during the LUSAS Modeller tabulation process.However, for an analysis that uses a control section, such as nonlinear, transient ordynamic analysis, it is necessary to specify how often results are required bysupplying a number of increments after which LUSAS Solver will write results to theplot file.

The information in the results file is stored in an unformatted or binary form andmay only be accessed using LUSAS Modeller. The plot file will contain the results ofthe analysis and sufficient model information to post-process the results. Full detailsof the finite element mesh (nodes and elements), material and geometric propertynumbers, support positions and equivalent nodal loads are stored in the results file.

To access results from the LUSAS analysis, files can be opened in a similar way tomodel files. See also Results Processing.

Note. Results files may be opened for write access, in a similar manner to modelfiles, allowing any defined combination, envelope or fatigue datasets to be saved withthe results file. Use the menu entry Files > Results File > Read With Write Accessto open the results file.

Command FilesCommand files may be created and used to store a sequence of LUSAS commandsfor replay at a later stage. Command files are particularly useful for subsequentreproduction of pictures or for storing combinations of commands which are usedfrequently. The following lists some suitable uses for a command file approach:

q Properties standard property definitions.q Mesh Divisions standard set of mesh discretisation datasets.


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q Command Sequences commonly used results assembly and displaysequences.

Command file manipulation is controlled using sub-menu entries below the mainFiles > Command File entry. See also Session Files and Open Recording. Thefollowing functionality is available:

q Open An existing command file is replayed by selecting it from the fileselector dialog box that results when the menu entry shown here is selected.Command files may be nested up to a depth of twenty files.

q Continue Entering a File Pause command in a command file will causeexecution to pause until this command is issued, when execution of the filewill continue from the position of the last FILE PAUSE commandencountered.

q Close will close a command file without continuing execution. Thiscommand can be issued only after a File Pause command has beenencountered in the command file.

q File > Save As If the .cmd extension is chosen this saves the currentlyopen model in the form of a command file, which when replayed willregenerate the current model definition. This can be a useful mechanism forrebuilding a corrupted model file. Saving the model as a command file canalso be used to merge the contents of two or more models into a singledatabase. Renumbering features will usually be required to ensure thatdatasets do not clash between models.

The parts of the model to save may be specified as all, selected items, visibleitems or selection memory items.

Note. Saving the model as a command file enables transfer of model data frommachine to machine or via electronic mail. This is because the command file isstored as readable ASCII text, whereas model files are stored in unformatted orbinary form. The command file is a compact form of model storage, but it is notdirectly upwards compatible and future versions of LUSAS may not read commandfiles saved in a previous version.

A useful feature of sub-session and command files is the use of the LUSASprogrammable interface language.

Tips for Writing Command Files

LUSAS command files can be written in an abbreviated form:

DEF POI 1 0 0

DEF POI 2 10 0

Command Files

27

DEF LI 1 1 2

DEF ME "line" BEAM 5 1@1 3@2 1@1

ASSI ME LI 1 1

DRA ME

DRA NOD LAB

or an expanded form:

DEFINE POINT PN=1 X=0 Y=0 Z=0

DEFINE POINT PN=2 X=10 Y=0 Z=0

DEFINE LINE BY_POINTS LN=1 PN=1;2

DEFINE MESH BY_NAME IMSH=1 FEATYP=LINE LNAME=BEAMNMBELM=5 RATIO=1@1 3@2 1@1

DRAW MESH COLOUR=100.100.100 LTYPE=0

DRAW NODEL LABEL HEIGHT=4.0 ROTATION=0.0COLOUR=0.100.100

There are several advantages in using the expanded form of command files. Allparameters are specified including default parameters, such as colours. This makesthe expanded form more readily understandable:

DRA ME => DRAW MESH COLOUR=100.100.100 LTYPE=1

Optional parameters can be omitted from a command file without the need to usecommas:

DRA ME ,, 1 => DRAW MESH LTYPE=1

Parameters from most commands may be specified in a non-default order:

DEF POI 1 5 10 8 => DEFINE POINT PN=1 Z=8 X=5 Y=10

Abbreviated commands may prove to be non-unique and cause errors in futureversions if new commands are added. It will therefore be easier to maintain upwardscompatibility between software versions if the full versions are used.

Case Study. Recording a Macro

A macro can be thought of as a series of commands that can be used again andagain. In LUSAS, macro recording is controlled using the command file facility. Acommand file may be opened at any time and a series of commands recorded. Oncestored, the command file may then be replayed at a later stage to execute thatrecorded sequence of commands. To record a macro, carry out the following steps:


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1. Create a command file using File > Command File > Open recording. You willneed to specify a valid filename. LUSAS will automatically append the correctextension (.cmd). You may find it useful to create a common area to store usefulmacro command files, e.g. c:\cmdfiles.

2. Execute the commands that are to be recorded. They will be recorded in LUSAScommand language in the opened command file.

3. Close the command file using File > Command File > Close recording.4. At this point the command file can be edited if alterations are required using a

text editor, for example to include a parametric capability or to add comments.5. When complete, replay the macro by opening it as a command file using File >

Command File > Open, or click on the command file open button .

Session Files and Open RecordingEach time LUSAS is entered a new session file, called LUSAS.ses, is created. Everysuccessfully completed LUSAS command, whether entered from the menus or viathe command line, is logged in this file using the LUSAS command language.

Any sub-set of commands may additionally be logged to an open recording commandfile. These files are of particular use in automatically generating command files.

The following functionality is available:

q Open recording a new sub-session file may be opened at any time byspecification of a valid filename. You will be prompted for confirmationbefore proceeding if a non-default file extension is specified or if the filealready exists.

q Close recording the sub-session file may then be closed after therequired sequence of commands or menu picks have been completed.

q Expand an existing sub-session file may have additional commands addedat a later stage using the Expand facility.

On a PC, up to four session files will be saved and renamed to LUSAS.bk1,LUSAS.bk2, etc. when a new session file is created. You can therefore recover fromerrors encountered in up to two sessions of work.

Case Study. Expanding Command Files into Session Files

To expand an abbreviated command file into the full form, carry out the followingsteps:

Print Files

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1. Open a new sub-session file using Files > Command File > Open recording.2. Invoke expanded files using Files > Command File > Expand.3. Open the abbreviated command file using Files > Command File > Open. The

commands it contains will be replayed and expanded into the active sub-sessionfile.

4. Close the sub-session file using Files > Command File > Close. The LUSASsub-session file, will now contain the full expanded form of the replayedcommand file.

Print FilesWhen any information is printed in LUSAS, it is sent by default to the text outputwindow. This output may alternatively, or in addition, be re-directed to a print file.A print file has a .prn extension.

Print file manipulation is controlled using menu entries below the main Files >Print File menu. The following facilities are available:

q Open The print file is opened by specifying a valid filename. LUSAS willprompt for confirmation to proceed if the specified file already exists or if anon-default file extension is used. All printed output is re-directed from thetext output window to the print file while it is open. Output to the screen canbe maintained while a print file is open by selecting the Print to Screen asWell when Printing to File button in the Files > Options dialog box.

q Close The print file may be closed at any time. With no print file open,printed output will be re-directed to the text output window.

q Annotate Lines of text can be added to the top of a print file beneath anyheader and title information. The annotation settings are controlled using themenu entry shown here. Apart from information advantages, print fileannotation can be useful for storing the contents of parametric variables,especially if they are required as input to a user-defined external program orawk script. See the chapter titled Parametric Language later in this manualfor full details.

Formatting Print FilesPrint file page layout format is controlled using the Files > Print File > PageFormat menu entry. Control of centre-, right- and left-justified headers, footers andtitles is provided. Headers and footers appear on every page while titles appear onthe first page only unless output on every page is requested. One blank line isautomatically added between header and title rows in the print file and two blank


30

lines are added below the title line before the printed output or any file annotationsbegin.

The following diagram shows where the specified text strings will appear on thepage.

Page layout settings are not used when saving the model as a command file using theFiles > Command File > Save Whole Model.

Macro fields can be used when specifying field content to represent values such asthe page number, date, software version in use, etc. Control is also provided forsetting page width and page length using the required number of columns and linesrespectively. The currently supported macro fields are shown below:

Macro Description

$CD LUSAS database creation date

$CV LUSAS database creation versionnumber

$DT Current Date

$LV LUSAS version number

$MD LUSAS database modified date

$MV LUSAS database modified versionnumber

$PN Page number

$PT LUSAS problem title

$VN LUSAS version number

$Evuser Accessed system environment variableuser.

Tip. Environment variables may be used in page format macros. This may beuseful for automatically picking up the name or telephone extension of an engineerand adding it to printed output using a standard company page definition. Theenvironment variable may consist of any valid text string. On a PC, environmentvariables are set using the DOS set command, and under UNIX the setenv commandis used. For full details of how to set environment variables consult thedocumentation supplied with your system.

To remove all page format information select Files > Print File > Disable PageFormat.

Print Files

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Case Study. Page Formatting of Text Output

The page format of the standard output of any LUSAS print command can be set asfollows:

1. Choose to set the page format using File->Print File->Page Format.2. Set the number of columns to 80. Set the number of lines per page to 60. In the

left justified header field add a title, e.g. BEAM RESULTS. In the right justifiedheader field add the date by entering the macro $DT.

3. Enter LUSAS $VN in the left justified footer field. This will include the LUSASversion number in this position. Add Page $PN in the right justified footer field.This will include the current page number. In the left justified title field add $PTwhich will insert the main problem title from the analysis data file. Finally, selectthe Add a Page Throw Character option and OK the dialog box.

4. Annotation can be added to the print file using File > Print File > Annotation Ifrequired. Annotation will appear in the print file below any header fields.

5. Print some results to the file, for example print displacements using PostView >Nodal Results > Print Components.

6. Close the print file using Files > Print File > Close.

The resulting text output will be formatted as follows:

BEAM RESULTS24/02/97

LINEAR STATIC ANALYSIS OF A CURVED CANTILEVER

LINEAR/DYNAMIC ANALYSIS

Current Results File = /gillian/anderson.mys ID 0

Current Selected Load ID = 1

Displacement Components In Global Axes

Node DX DY THZ DURSLT

1 .0000E+00 .0000E+00 .0000E+00.0000E+00 .0000E+00

3 3.420 -4.799 -.2740E-01.0000E+00 5.893

4 .6200 -.1629 -.1520E-01.0000E+00 .6410


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5 1.901 -1.044 -.2364E-01.0000E+00 2.169

6 3.005 -2.711 -.2692E-01.0000E+00 4.047

7 .0000E+00 .0000E+00 .0000E+00 .3147E-01 .0000E+00

8 .0000E+00 .0000E+00 .0000E+00 .7655E-01 .0000E+00

9 .0000E+00 .0000E+00 .0000E+00 .9843E-01 .0000E+00

10 .0000E+00 .0000E+00 .0000E+00 -.1048.0000E+00

LUSAS 12.1-0Page 1

About Interface FilesInterface files are used to transfer external drafting, modelling or material data inand out of LUSAS. The full model or a portion selected using the selection memorycan be exported for use in third party graphics and analysis package files.

The currently supported list of interface file formats is as follows:

q DXF AutoCAD Drawing Exchange Format. AutoCAD and DXF aretrademarks of Autodesk, Inc.

q IGES Initial Graphics Exchange Specification. IGES/PDESq PATRAN Neutral file format for inputting phase I geometry information and

outputting phase II mesh information. PATRAN is a registered trademark ofthe MSC Corporation.

q CACE-Drape which allows LUSAS to export mesh data to the CACE-Drapepackage for composite material definition and import and tabulate theresulting composite material lay-up information.

Import and export of interface data is accessed from the File menu. The followingoptions are available:

q File > Import controls import of an Interface file into LUSAS byselecting using the menu entry shown here. After all feature entities havebeen imported, a feature MERGE will be carried out according to the settingof the merge parameter.

About Interface Files

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q File > Export controls export to an Interface file from LUSAS.

A file extension will be assumed if none is specified. For DXF files an extension of.dxf will be assumed, for a PATRAN neutral file a .def extension will be assumed,for an IGES file a .igs extension will be assumed and for a CACE-Drape file a .lypextension will be assumed. Filenames are case sensitive in the UNIX operatingsystem.

Note. DXF and IGES files often contain much more detailed information than isrequired to create a finite element model, so a certain amount of model tidying mustbe expected after carrying out an import. Tidying may involve splitting complexfeature geometry into simpler building blocks to aid meshing, or conversion of splineand bicubic surface data into straight Lines, arcs and planar surfaces. See TidyingImported Lines and Surfaces for details of Line and Surface conversion.

DXF Interface FilesDXF ImportThe AutoCAD Drawing Exchange Format or DXF file, as it is more commonlyknown, can be used to import and export data to and from LUSAS.

DXF entities supported by the LUSAS DXF import facility are listed in the tablebelow.

DXF Entity Imported as LUSAS Feature

POINT Point

LINE Straight Line

3DLINE Straight Line

ARC Arc Line

CIRCLE Two arc Lines

POLYLINE Spline Line

SOLID Straight-edged Surface

3DFACE Straight-edged Surface

TRACE Straight-edged Surface

POLYGON MESH Multiple straight-edged Surface

POLYFACE MESH Bicubic Surface

Extended Entities

Not supported.

Tip. Units and entity orientation can be modified by defining a local coordinate setand making this the default before importing. For example, the units may be


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changed from mm to m during conversion by defining a scale local coordinatedataset with x, y and z scale factors of 1e-3. The entity orientation may be changedfrom landscape to portrait with the aid of an XY rotation local coordinate datasetwith an angle of 90 degrees.

Notes

q The amount of information which may be transferred via the DXF file islimited due to limitations in the DXF file format (for example, a volumecannot be expressed in standard DXF data).

q AutoCAD version 13 uses DXF extended entities for some items. LUSASdoes not support import of extended entities and will warn to this effect if anAutoCAD version 13 DXF file is detected.

q Closed surfaces are not translated by LUSAS.q Closed poly-lines and three-sided polygon meshes are not translated.

DXF ExportA DXF interface file may be created from LUSAS for use in an external program.LUSAS datasets are converted into their equivalent DXF entity. Control over theamount of information exported is provided, i.e. All or Active features and/or meshmay be specified. This is valid for both pre-processing model files and results files.The following parameter is available on the export dialog to control creation of DXFfiles:

q Level Indicator indicates whether Features Only, Mesh Only orFeatures + Mesh are to be exported. The level indicator is only requiredwhen a model file is open and features are active. When no model is active,such as during post-processing, only the mesh is exported. Additional optionsare available to include Volume mesh entities in the export process. Onlyelement faces are exported when exporting Volume feature mesh records.

LUSAS feature types supported by the DXF export facility are listed in the tablebelow:

LUSAS Feature/Mesh Exported as DXF Entity

Feature LINE (straight) 3DLINE

Feature LINE (arc) ARC

Feature LINE (spline) POLYLINE

Feature SURFACE (straight-edged) 3DFACE

Feature SURFACE (general curved) 3DLINE/ARC/POLYLINE

Mesh LINE (linear or quadratic edge) 3DLINE

Mesh SURFACE (linear or quadratic face) POLYFACE MESH


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LUSAS Feature/Mesh Exported as DXF Entity

Mesh VOLUME (linear or quadratic face)

PLOYFACE MESH

Note. The exporting of models generates DXF files containing structuralinformation only. This facility is not intended for exchanging graphical information,for this purpose picture files should be used.

For further information on the DXF file format, users are referred to the AutoCAD Reference Manual.

IGES Interface FilesThe IGES interface only supports import of fixed length ASCII IGES files. Allcurve and surface geometric type entities are translated into LUSAS except entitytype 130 (offset curves). See the table below for full details of supported IGESentities.

No model scaling is carried out during import. Any active Local Coordinate datasetswill be ignored. All IGES solid geometry, annotation, line type and font data is alsoignored. The boundary lines of a trimmed surface are translated into LUSAS but arenot formed into a surface as the IGES surface may contain holes which are notsupported by the LUSAS Surface type.

The following parameters are available on the import dialog to control import ofIGES files:

q Number of Points Along Splines and Number of SplinesAcross Surfaces large numbers of LUSAS features can be generatedduring the import process. These command parameters are provided on theimport dialog to reduce the numbers of features defined to some degree. Bothparameters have a default value of 10, a value of 0 will allow LUSAS todecide how many features to use.

q Level Number to Process each entity in an IGES file can have alevel number associated with it. Different views or models can be stored in thesame file on different levels. This parameter allows selection of one or all ofthese levels. The default value is 0 which translates all levels in the file. Seethe related tip below.

q Minimise Number of Splines turns on/off a facility to minimise thenumber of points defining a spline without loss of definition. When turned on,this facility will slow down the import process considerably.

q Translate Annotation Type Geometry Entities turns on/offtranslation of annotation type geometric entities. Annotations in an IGES file,


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such as lines or boxes are usually flagged as an annotation and LUSAS can beset to read this type of entity or they will be ignored.

Tip. To find out what level numbers exist in an IGES file a spurious number can beinput such as 10001. LUSAS will proceed with the import and output a summary tothe text window. This summary will contain a list of the level numbers. The file maythen be repeatedly imported using different individual level numbers to view thecontents of each level.

The LUSAS merge tolerance is set from the IGES file global parameters if theMinimum Resolution parameter is specified in the file.

IGES Entity Description Imported as LUSAS Feature

100 Circular arc Arc Line, or if the subtended angle islarge, several arcs defining a singlecombined line.

102 Compositecurve

Combined Line.

104 Conic arc Spline Line

106 Copious data Combined Line defined by manystraight lines or a single surface.

108 Plane Surface.

110 Line Straight Line.

112 Parametricspline curve

Spline Line or a single combined linedefined by many splines.

114 Parametricspline surface

Many single patch bicubic Surfaces.

116 Point Point.

118 Ruled surface Surface.

120 Surface ofrevolution

Surface or bicubic Surface for eachLine swept. If the sweep angle is largethe sweep is taken in two or threestages to generate two or threesurfaces for each swept line.

122 Tabulatedcylinder

Surface.

124 Transformationmatrix

Read from the file and used in thetranslation but not stored in theLUSAS database.

126 Rational B-spline

Spline Line or single Combined Lineof splines.


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IGES Entity Description Imported as LUSAS Feature

128 Rational B-spline surface

Bicubic Surface.

130 Offset curve Currently unsupported.

140 Offset surface Surface for each surface that is offset.

142 Curve on aparametricsurface

Line depending on the parent line(boundary line of a trimmed surface).

144 Trimmedparametricsurface

Surface depending on the parentsurface (support surface of a trimmedsurface).

PATRAN Interface FilesAbout PATRANPATRAN is an external pre-and post-processing system. The PATRAN neutral filecontains the full finite element model information. The Neutral file is split into twodata categories: Phase I contains the definition of the geometric entities, and Phase IIcontains all of the finite element (node and element) information.

PATRAN ImportPhase I data (geometric entities) is read from the PATRAN neutral file. Phase II datais ignored. The following table shows the supported Neutral file packet types forimport into LUSAS:

Packet Title LUSAS Equivalent

25 Title Used for information purposes only.

26 Time/Date/Version

Used for information purposes only.

31 grid Point.

32 line Spline Line defined by 2 Points.

33 patch Bicubic Surface defined by 4 splineLines.

34 hyperpatch Volume.

47 trimmed surfaceBicubic Surface and spline Linesdefining the trimmed regions.

Tip. Imported PATRAN data is particularly suited to tidying, since all definedgeometry is spline data. See Tidying Imported Lines and Surfaces for more details.


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PATRAN ExportThe LUSAS PATRAN interface exports only phase II data (node and elementinformation). Both the undeformed and deformed mesh may be exported. If adeformed shape is required, a LUSAS results file must be loaded in addition to therelevant model file.

LUSAS load types supported by the PATRAN export facility are listed in the tablebelow:

LUSAS Load Type PATRAN Neutral Packet

PDSP (Prescribed variable) Type 8.

CL (Concentrated load) Type 7, 15.

ELDS (Element loads) Not supported.

UDL (Uniformly distributed load) Type 6.

FLD (Face load) Type 6, 16.

CBF (Constant body force) Not supported.

VELO (Initial velocity) Not supported.

SSI, SSIE, SSIG (Initial stresses and strains) Not supported.

SSR, SSRE, SSRG (Residual stresses and strains)Not supported.

TEMP (Nodal temperature) Type 10.

TMPE (Element temperature) Type 11.

ENVT (Environmental temperature) Not supported.

TDET (Temperature dependent ENVT) Not supported.

RIHG (Rate of internal heat generation)

Not supported.

The following table details supported and unsupported Packet Types in the PATRANNeutral File exported by LUSAS.

Packet Title Description

01 Nodal Data Fully supported.

02 Element Data To orient joint elements a Coordinate Frame (05) isassigned to each joint element. In PATRAN 2.5 thisCoordinate Frame is assigned to the joint by writing theCoordinate Frame ID in the Congruent element ID field. InPATRAN 3 this is not the case since each joint element hasits own geometric dataset in which the Coordinate Frame iswritten. The format is controlled via the system variableELMPRP.


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03 MaterialProperties

Isotropic, 2D and 3D anisotropic, field isotropic and 3Dorthotropic materials are all supported. All nonlinearmaterials are partially supported. The mass Rayleighdamping constant in LUSAS is mapped onto the Structuraldamping coefficient (CE) in PATRAN. The stiffnessRayleigh damping constant will be lost during export.Plasticity, Hardening, Creep, Damage properties andcomposite materials are not supported.

04 ElementProperties

The formatting of this packet may be affected by changingthe system variable ELMPRP. In PATRAN 2.5 format theitems are ordered as follows: material ID, geometricproperties, or for joint elements: material ID, jointproperties, geometric properties. In the case of joints thefirst item does not reference a PATRAN material ID butdefines the joint property ID used in the MATERIALASSIGNMENTS data chapter within LUSAS. In PATRAN3 format the items are listed as: geometric properties, or forjoint elements: joint properties, geometric properties,coordinate set.

05 CoordinateFrames

If joints are exported a coordinate frame will be created foreach joint element. These packets may be distinguishedfrom user-defined coordinate frames by looking at the lastentry of the Header Card. Coordinate frames associatedwith joints will all have 1 in the last position (N5) of theHeader Card while user-defined coordinate frames have 0.

06 DistributedLoads

Slidelines are represented in PATRAN by pressure loads.Master slidelines are assigned a Load Set ID in the range1000-1999 and the corresponding slave slidelines areassigned a Load Set ID in the range 2000-2999. If elementswith midside nodes are used then constraint equations willbe set up to ensure that the displacement of the midsidenode is linear with respect to the corner nodes. All slideproperties will be lost when exporting. The magnitude ofthe applied pressures within this load case represents acode: pressure = nnnst, where nnn indicates the slidelinenumber, s indicates master (1) or slave (2) and t indicatesthe slideline contact type: sliding (1), sliding with friction(2), tied slideline (3) and sliding only with no lift-off (4).Thermal surfaces will not be exported unless they form athermal gap/contact or radiation surface. If elements withmidside nodes are used then constraint equations will beset up to ensure that the displacement of the midside nodeis linear with respect to the corner nodes. Thermal gaps andcontact surfaces are exported as a nodal pressure load withLoad Set ID in the range 3000-3999. Gap and contact


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Packet Title Descriptionproperties will be lost. Radiation surfaces are representedin PATRAN by assigning a nodal pressure load with LoadSet ID in the range 4000-4999. Each radiation surface willbe converted to a unique pressure load set. Radiationproperties will be lost except for the emissivity which iswritten into packet 18 directly after each pressure value inthe file. Radiation symmetry definitions will also be lostduring export.

07 Node Forces Concentrated loads (CL) in a structural analysis are writtento this packet.

08 NodeDisplacements

Spring supports are not supported by the PATRAN NeutralFile format and will be converted to restrained supportfreedoms with zero displacement.

09 Bar ElementInitialDisplacement

Not supported.

10 NodeTemperatures

In a field analysis prescribed variables (PDSP), supportconditions in field problems as well as temperature loads atnodes (TEMP) are all written here.

11 ElementTemperatures

Temperature loads for elements (TMPE) are written to thispacket. Temperature loads at nodes (TEMP) and forelements (TMPE) generally have eight components inLUSAS while the PATRAN equivalent, 10 and 11, does nothandle initial temperatures and gradients. Therefore onlythe first component (the current temperature) will beexported. Also, TMPE loads in LUSAS may be applied to aselection of nodes with different temperatures within theelement. In 11 only one temperature value (the averagednodal value) is applied to all nodes within the element.Because of this limitation in the PATRAN Neutral Fileformat users should use TMPE loading with caution.

12 DOF Lists Not supported.

13 P/MECHANISM Entities

Not supported.

14 MPC Data User-defined as well as automatically created constraintequations will be written into this packet.

15 Nodal HeatSource

Concentrated loads in a field analysis are written to thispacket.


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16 Distributed HeatSource

Face loads in a field analysis are written here.Environmental temperature loading (ENVT) is notsupported by the PATRAN Neutral File format. Theconvective heat transfer coefficient as well as the radiationheat transfer coefficient is however exported into PacketTypes 17 and 18. The radiation heat transfer coefficient isdivided by Stefan Boltzmanns constant to obtain aneffective emissivity.

17 ConvectionCoefficients

Convection Coefficients will be written when exportingenvironmental temperature loads (ENVT).

18 RadiationEmissivityValues

This will be written when exporting environmentaltemperature loads (ENVT) and when exporting radiationsurfaces.

19 View FactorData

Not supported.

21 NamedComponentDefinition

The mesh node and element information is extracted fromthe named features and exported into this packet.Component names will be truncated if the name is morethan 12 characters long.

25 Title Card Supported.

26 Summary Data The PATRAN release number may be set to either 2.5(default) or 3.0 by changing the system variable PATVER.

There are two system parameters that will affect the format of the resultingPATRAN neutral file:

q PATVER Version number printed in the summary. The default value is 2,which will print 2.5 in the summary data packet. If data from PATRANversion 3 or higher is required, this parameter should be set to 3.

q ELMPRP controls the formatting of the element properties (04) andelement data (02) packets, which are different for PATRAN version 2.5 and 3and above. If the PATRAN neutral format for version 3 or above is required,this parameter should be set to 3. If this parameter is not set, or if it is set toanything other than 3, then a PATRAN 2.5 neutral file will be created.

System parameters can be set in a start-up files.


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CACE-Drape Interface FilesAbout CACE-DrapeLUSAS is able to export mesh data to the CACE-Drape package for specification ofcomposite material properties and lay-up information. The resulting information canbe imported and tabulated to the LUSAS data file for analysis.

Note. Since CACE-Drape is used for thin laminates only, solid compositeelements may not be used with this facility.

CACE-Drape ImportThe following parameter is available on the import dialog to control import ofCACE-Drape files:

q Type of Data specifies the type of data to be imported. Options are ReadNew Data to be used if a new file is to be read or Delete Existing Data if theexisting stored CACE-Drape data is to be deleted. LUSAS will alwaystabulate using the CACE-Drape data, in preference to any compositeassignments to the features, as long as the data exists in the LUSAS database.To revert to using the LUSAS data use this facility to delete any previouslyimported CACE-Drape data.

When importing data from CACE-Drape into LUSAS, no checks of the elementtopology or geometry are made. LUSAS assumes element number 3 from CACE-Drape corresponds to the current element number 3 in LUSAS.

Data from CACE-Drape is used to tabulate the LUSAS data chapters shown in thetable below.

LUSAS Data Chapter Details

Geometric Properties Containing total element thickness

Composite Geometry Containing ply thickness ratios

Geometric AssignmentsAssigning geometric properties toelements

Material Properties Defining orthotropic plane stressproperties

Composite MaterialProperties

Defining ply material, orientation angleand name

Composite AssignmentsAssigning composite geometry/materialsto elements.


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CACE-Drape ExportOnly node and element data is exported. Control over data exported is availableusing four options:

q All itemsq Selected items Parts of the model currently selected with the mouse.q Visible items Parts of the model can be made invisible when they are formed

into groups.q Selection memory items Geometry held in selection memory.

Tidying Imported Lines and SurfacesWhen geometry is imported into LUSAS, Lines are often created as splines andSurfaces as bicubic Surfaces. This can create cracks in the LUSAS model as splineswhich are physically coincident may have different tangents and twist vectors. Atidying procedure must be used to simplify the features to use simpler formulationswhere applicable. This facility can be used on all Line and Surface datasets. Afeature does not have to be imported to be suitable for conversion.

Splines approximating to straight Lines or arcs and Surfaces approximating to theLUSAS special case Surfaces (Cylindrical, Conical and Spherical) can be convertedinto their simpler regular equivalent.

Individual Line and Surface conversion can be accessed via Geometry > Line >Convert and Geometry > Surface > Convert respectively.

Whether splines are converted to straight lines or not is controlled by the StraightLine Tolerance. Whether splines are converted to arcs or not is controlled using theAllowable Variation in Spline Radius (%). Both may be specified after issuing thecommand.

Case Study. Removing Cracks from Imported Data Using Convert

Using a combination of Incremental Rotation and convert lines, cracks introduced byvariations in spline definitions may be removed. The following procedure should beused:

1. Carry out the Import of the PATRAN neutral file using File > Import.

2. Use the dynamic rotation tool 3. to draw the model outline. This will visualise the cracks.4. Tidy the imported lines using the Geometry >Line > Convert command. This

will convert any splines within the specified Straight Line Tolerance to straightlines and those within the Allowable Variation in Spline Radius to arcs.


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5. Merge the features and redraw the outline. If any Lines have not beenmerged try increasing the tolerances (File > Model Properties, Geometry tab)and try again.

6. Tidy any Surfaces required using the Geometry >Surface > Convert command.7. View the model again using dynamic rotation.

Picture FilesAbout Picture FilesPicture files may be used for storing graphical information in a neutral format forsubsequent redisplay in LUSAS or for conversion to plotter-dependent graphics files.Picture files are stored in readable text format using the format shown in the tableoverleaf.

Manipulation of Picture FilesPicture files may be save using the File > Picture Save menu entry in either .pic or.wmf format.

Note. Picture files are written only during the graphical operations that drawinformation to the screen, they cannot be opened in retrospect once the requiredpicture has been created.

Warning. If the screen is erased, either wholly or partially, while a picture file isopen, the picture file will be initialised and all previous contents will be lost. Thismistake is especially easy to make when working with sub-windows. Also, if asection of the screen is selectively erased by use of annotation in the backgroundcolour this will be recorded by the picture file, but its treatment when obtaining ahardcopy is plotter dependent.

Picture File FormatPicture files are stored in readable text format. The individual picture file records usethe following general format:

code, r1, r2, r3, r4, i1, i2, i3

format (i5, 4f10.3, i10, 2i5)

This information can be used to write programs that will read information stored inthe picture file and carry out additional processing. The information is stored inpackets of data as defined in the following table.

Picture Files

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Code Function Parameters Description

1 Move r1, r2 Moves to the drawing location specified by the x(r1) and y (r2) coordinate (mm).

2 Draw r1, r2 Draws a line from the current position to thedrawing location specified by the x (r1) and y(r2) coordinate (mm).

3 Symbol r1, r2, r3,r4, i1

Plots a LUSAS built-in symbol at a specifiedscreen position.

4 Character r1, r2, r3,r4, i1

Plots an ASCII character at a specified screenposition with: x coordinate (r1), y coordinate(r2), rotation angle in degrees (r3), characterheight in mm (r4) and ASCII character code(i1).

5 Colour r1, r2, r3 Percentage colour content with: red % (r1),green % (r2) and blue % (r3).

6 r1 Percentage of colour spectrum (r1)

7 r1, r2, r3,r4, i1

Colour number (i1). Real numbers (r1-r4) notused.

8 PolygonFill

r1, r2, r3,r4, i1, i2, i3

Creates a colour-filled multiple-sided polygonwith: colour number (i1), number of vertices(i3). Integer (i2) and real numbers (r1-r4) arenot used.

9 r1, r2, r3,r4, i1

Creates a colour-filled multi-sided polygon with:number of vertices (i1). Real numbers (r1-r4)are not used.

0 r1, r2 Creates a polygon vertex with: x and ycoordinate (r1-r2). Must be used in conjunctionwith and appear immediately after code 8 or 9above.

10 WindowCoordinates

r1, r2, r3,r4, i1

Indicates window size and status with:coordinates (r1-4) and flag to indicate status(i1). Status flag indicates new window (i1=0) orfull screen (i1=1).

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