Presentation of PAM-CRASH v2004. Part 2: Inputchecks. Part 2: Inputchecks

Transcription

1 Presentation of PAM-CRASH v2004 Part 2: Inputchecks Part 2: Inputchecks. 1

2 General 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 2

3 V2004: Enhanced 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 switch able checks 3

4 Data 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.!

5 10 Node TET Element with bad element shape 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: 5

6 10 Node TET Element with bad element shape Examples for bad Jacobian Both checks cannot switched off but can be influenced by parameters. 6

7 4 - Node 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: 7

8 2D-Element Check: Internal 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 contactalgorithm The error message given by the check: *** ERROR *** QUAD 1 IS UNACCEPTABLE: TWO CONNECTED EDGES ARE PARALLEL Switched by SHELLCHECK YES(/NO) 8

9 Frame type 1 and 2 used by KJOINT, JOINT 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 9

10 Wrong analytical strain rate model for MAT 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 10

11 Material type 301 with failure and zero distance 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 11

12 Node ID used for more then one rigid body COG This is not allowed and may lead to wrong results. Never checked in previous 2G versions 12

13 Keyword 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 13

14 Airbag Skin and Chamber Orientation Check 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 14

15 Airbag Skin and Chamber Orientation Check (contd( contd.) 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 SURFACE NOT UNIQUE LIST OF ELEMENTS WITH INCONSISTENT ORIENTATION: END OF AIRBAG CHECK 15

16 Airbag Skin and Chamber Orientation Check (contd( contd.) Force solver to ignore Optional keyword AIRBAGCHECK NO 16

17 Airbag Closed Volume Check Consequence of nonclosed volume Volume calculation wrong Consequently pressure calculation wrong Influence on results depends on location of elements Case 2: supporting structure may be loaded Case 1: considerable influence Case 2: influence not obvious (volume not closed at inflator location, hole fixed by BOUNC) 17

18 Airbag Closed Volume Check (contd( contd.) Possibilities to check Mesh generation tool Look for free edges CrashSafeEditor 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 : VOLUME NOT CLOSED HOLE IS COMPOSED BY THE FOLLOWING ELEMENTS: END OF AIRBAG CHECK 18

19 Airbag Closed Volume Check (contd( contd.) Force solver to ignore Optional keyword AIRBAGCHECK NO 19

20 Metric Topology Check Background Approximate and reference mesh need to be topologicaly identical, i.e. edge numbers between both meshes must be consistent In case of disconnected meshes, corresponding edges need to have identical length If these requirements are not met, unphysical initial stresses occur Approximate mesh Reference mesh 20

21 Metric Topology Check (contd( contd.) Possibilities to check Mesh generation tool Solver Error message in output listing (see below) BEGINNING OF METRIC CHECK PARAMETER VALUES : EDGE TOLERANCE FOR DISCONNECTED ELEMENTS E-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 21

22 Metric Topology Check (contd( contd.) Force solver to ignore Optional keyword METRICCHECK NO 22

23 Slipring Nodes Coincidence Check 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 / NAME slipring $ ELE END ELE END 23

24 KW 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 24