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PresentationPresentation of PAMof PAM--CRASH v2004CRASH v2004

Part 2: InputchecksPart 2: Inputchecks..

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General SituationGeneral Situation

Problem for industrial CRASH/SAFE simulation: Dataset is very large

Dataset is very complex

Dataset is assembled with components of Suppliers

Colleagues

Old models (cut and paste)

Dangerous and wrong definitions very difficult to find

Solution: Improve Solver data check

Solver has to be strict for data check

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V2004:V2004: Enhanced Data ChecksEnhanced Data Checks

To improve model quality for more stable and

accurate results.

All switch able checks are activated by default.

Switch able checks can be turned off to produce

results without changing existing data sets.

But it is NOT recommended, to turn off the switchable checks

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Data ChecksData Checks

+-------------------------------------------------------------+

! IMPORTANT - IMPORTANT - IMPORTANT - IMPORTANT - IMPORTANT !

+-------------------------------------------------------------+

! !

! THE FOLLOWING IMPROVEMENTS ON DATACHECK MAY STOP YOUR RUN: !

! !

! 1) AIRBAG SKIN AND CHAMBER ORIENTATION CHECK !

! 2) AIRBAG CLOSED VOLUME CHECK !

! 3) METRIC VERSUS INPUT MESH TOPOLOGY CHECK !

! 4) 4-NODE DEGENERATED HEXA ELEMENT !! 5) INTERNAL ELEMENT ANGLE 0 or 180 DEGREE !

! 6) FRAME TYPE 1 AND 2 USED BY KJOINT, JOINT, THLOC !

! 7) 10-NODE TETRA WITH BAD ELEMENT SHAPE (NEGATIVE JACOBIAN)!

! 8) KEYWORD MATCH WITH 8 CHARACTERS !

! 9) NON COINCIDENT NODES FOR SLIPRING DEFINITION !! 10) WRONG ANALYTICAL STRAIN RATE MODEL FOR MAT TYPE 25, 41 !

! 11) MATERIAL TYPE 301 WITH FAILURE AND ZERO DISTANCE !

! 12) NODE ID USED FOR MORE THEN ONE RBODY COG !

! !

! DATACHECKS 1, 2, 3, 4 AND 5 CAN BE SWITCHED OFF. !+-------------------------------------------------------------+

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10 Node TET Element with bad element10 Node TET Element with bad elementshapeshape

To avoid stability problems (neg. volume, timestep)

Two tests are implemented:

Position of the middle node

Calculation and check of the Jacobian at different

locations

Examples for bad position of the middle node:

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10 Node TET Element with bad element10 Node TET Element with bad elementshapeshape

Examples for bad Jacobian

Both checks cannot switched off but can be

influenced by parameters.

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44 -- Node Degenerated HEXA ElementNode Degenerated HEXA Element

Four node degenerated HEXA are too soft and not

efficient in terms of CPU time Therefore the new four node TET should be used.

Example for degenerated HEXA

Test can be switched off:

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2D2D--Element Check:Element Check:Internal angle 0 or 180 degreeInternal angle 0 or 180 degree

To avoid numerical problems (core dump, floating

invalid)

Contact algorithm (platform dependent): there is a

risc of 50% to get zero-area triangle in the contact-

algorithm

The error message given by the check:

*** ERROR *** QUAD 1 IS UNACCEPTABLE: TWO CONNECTED EDGES ARE

PARALLEL

Switched by

SHELLCHECK YES(/NO)

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Frame type 1 and 2 used by KJOINT,Frame type 1 and 2 used by KJOINT,JOINT and THLOCJOINT and THLOC

To avoid confusion with frame types Only Frame type 0 allowed for above entities (just to initialize)

During solution each entity treats and updates his own internal

frame What happens if the same frame is used for more then one

KJOINT?

To improve DMP performance Frame type 2 needs very expensive DMP communication even if

the frame is not used

Use the ESI-tool FIXFRAME to fix the model

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Wrong analytical strain rate model forWrong analytical strain rate model forMAT 25, 41MAT 25, 41

To avoid confusion for users

Solver switch to support analytical law, but no INFO

or WARNING for users in previous version

Was implemented for V2001 solver (global

analytical strain rate switch). Never updated for 2G

solver

only ISTRAT=1 allowed

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Material type 301 with failure and zeroMaterial type 301 with failure and zerodistancedistance

Distance needed to predict tension/compression.

Failure will happen only for tensile load

Previous version uses segment normal if distance

is zero. But no info or warning for users.

The check is only active, when ITENS=0

N d ID d f h i id

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Node ID used for more then one rigidNode ID used for more then one rigidbody COGbody COG

This is not allowed and may lead to wrong results.

Never checked in previous 2G versions

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Keyword match with 8 charactersKeyword match with 8 characters

To be consistent with the manual

To make sure that a dataset passed the solver will

be processed by 3rd party pre processors/tools

(which strictly follow the manual) as well

Ai b Ski dAi b Ski d Ch bCh b O i t tiO i t ti

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Airbag Skin andAirbag Skin and ChamberChamberOrientationOrientationCheckCheck

Pressure and volume

calculation depends on

uniform airbag outer surface

orientation !

Element normals need to point

outwards Pressure direction wrong, for

elements with reversed

orientation

Consequence: different

mechanical behaviour


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Airbag Skin andAirbag Skin and ChamberChamberOrientationOrientationCheck (Check (contdcontd.).)

Possibilities to check

CrashSafeEditor

Mesh Normals Orientation Show

Normals are displayed in the graphical window Safety Airbag Definition Check

Warning message is issued

Solver

Error message in output listing (see below)

BEGINNING OF AIRBAG CHECK

CHECK FOR AIRBAG ID. 1

*** ERROR *** AIRBAG ID. 1 CHAMBER NUMBER 1 : ORIENTATION OF SURFACENOT UNIQUE

LIST OF ELEMENTS WITH INCONSISTENT ORIENTATION:

161 162 163 164 165

166 167 168 169

END OF AIRBAG CHECK


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Airbag Skin andAirbag Skin and ChamberChamberOrientationOrientationCheck (Check (contdcontd.).)

Force solver to ignore

Optional keyword

AIRBAGCHECK NO

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AirbagAirbag ClosedClosed VolumeVolume CheckCheck

Case 1:considerableinfluence Consequence of non-

closed volume

Volume calculation

wrong

Consequently pressure

calculation wrong Influence on results

depends on location of

elements

Case 2: supportingstructure may be

loaded

Case 2: influence notobvious (volume notclosed at inflatorlocation, hole fixed byBOUNC)

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AirbagAirbag ClosedClosed VolumeVolume Check (Check (contdcontd.).)


Mesh generation tool

Look for free edges

CrashSafeEditor Safety Airbag Definition Check

Warning message is issued

Solver


BEGINNING OF AIRBAG CHECK

CHECK FOR AIRBAG ID. 1

*** ERROR *** AIRBAG ID. 1 CHAMBER NUMBER 1 : VOLUME NOT CLOSEDHOLE IS COMPOSED BY THE FOLLOWING ELEMENTS:

131 134 135 136 161

162 225 228

END OF AIRBAG CHECK

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AirbagAirbag ClosedClosed VolumeVolume Check (Check (contdcontd.).)


Optional keyword

AIRBAGCHECK NO

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MetricMetric TopologyTopology CheckCheck

Background

Approximate and reference

mesh need to be topologicalyidentical, i.e. edge numbers

between both meshes must be

consistent

In case of disconnectedmeshes, corresponding edges

need to have identical length

If these requirements are

not met, unphysical initial

stresses occur

Approximate mesh

Reference mesh

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MetricMetric TopologyTopology Check (Check (contdcontd.).)


Mesh generation tool

Solver


BEGINNING OF METRIC CHECK

PARAMETER VALUES :

EDGE TOLERANCE FOR DISCONNECTED ELEMENTS .. 0.5000E-01

*** ERROR *** ELEMENT ID: 14 MESH TOPOLOGY OF INPUT FILE AND METRIC FILE

DOES NOT FIT. CHECK CONNECTIVITIES

*** WARNING *** EDGE LENGTH IS DIFFERENT BETWEEN INPUT FILE AND METRIC FILE FOR

DISCONNECTED ELEMENTS: 2 AND 3

*** WARNING *** EDGE LENGTH IS DIFFERENT BETWEEN INPUT FILE AND METRIC FILE FOR

DISCONNECTED ELEMENTS: 12 AND 13

END OF METRIC CHECK

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MetricMetric TopologyTopology Check (Check (contdcontd.).)


Optional keyword

METRICCHECK NO

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SlipringSlipring NodesNodes CoincidenceCoincidence CheckCheck

Slipring node (= structure

attachment node) and attached

node, need to be at the same

location

Otherwise constraint algorithm

does not work exact

$ idsr nodfx fric tol fract

SLIPR / 1 103 0.2 0.01 0.1

NAME slipring

$ELE 11 12

END

ELE 13 14

END

S

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KW SelectionKW Selection

The following data checks are improved:

KW selection ERROR because of non existing parts, nodes or

elements

Error message for elements with missing part definition

Documents

V2004