element sizes in crash calculation - dynamore gmbh
TRANSCRIPT
Element Sizes in Crash Calculation
Dipl.Dipl.--IngIng. . UdoUdo JankowskiJankowski, , Dr.Dr.--IngIng Martin MMartin Müüller ller BechtelBechtel, Dipl., Dipl.--Ing. Ing. Manfred Manfred SansSans, Tecosim GmbH, Tecosim GmbH
4. LS4. LS--DYNA Forum, 20.DYNA Forum, 20.--21. Oktober 2005,21. Oktober 2005, BambergBamberg
Agenda
Tecosim-best partner for simulation
Introduction
FE Experiments with varied parameters
Analysis of Results/ Conclusion
Outlook
Investigation on mesh density in LS Dyna
© 2005 Copyright by DYNAmore GmbH
4. LS-DYNA Anwenderforum, Bamberg 2005 Modellierung
I - I - 33
AMG
AutolivBayer AGBentlerBertoneBosch/ BlaupunktDegussa-Hüls AGDynamit NobelEADSFaureciaGetragHella KGJohnson ControlsKarmannLearMagnaThyssenkruppTRW AutomotiveMahleMANMannesmann/SachsSiemens VDOWagon Automotive
Audi AGAdam OPEL AGClaasDaimler ChryslerDaihatsuFiatFORDGeneral MotorsHONDAISUZUKIAJohn DeereJaguarLandroverNissanPORSCHE AGToyota
LeonbergLeonberg Basildon (UK)Basildon (UK) Coventry (UK)Coventry (UK)
Rüsselsheim
Köln
Locations & References
Igenie OfficeIgenie OfficeTokio (Japan)Tokio (Japan)
CAE PortfolioCAE Portfolio
SafetySafetyCRASHCRASH
NVH / DurabilityNVH / Durability
CFD
PowertrainPowertrain
Multi Body Systems Multi Body Systems (MBS)(MBS)
Software devSoftware devOptimizationOptimization
CPU time
0
100
200
300
400
500
600
700
800
900
1 2 3 4 5 6 7 8
CPU #
CPU
tim
e [s
] standardscale_cscale_c2scale_xscale_y
SeatsSeats
CAE Portfolio
© 2005 Copyright by DYNAmore GmbH
Modellierung 4. LS-DYNA Anwenderforum, Bamberg 2005
I - I - 34
Any sufficiently advanced technology is indistinguishable from magic.
„Profiles of the future“ (1961) by Arthur C. Clarke (2003)
Introduction
Why do we simulate?Why do we simulate?
Introduction
Cost effectiveCost effective
FastFast
Proven methodProven method
We cannot test!We cannot test!
© 2005 Copyright by DYNAmore GmbH
4. LS-DYNA Anwenderforum, Bamberg 2005 Modellierung
I - I - 35
Number of Elements for a FE Crashmodel BIW
0
500000
1000000
1500000
2000000
2500000
1999 2000 2001 2002 2003 2004
# of Elements
Introduction
How should a mesh look like?
Introduction
TEC|ODM Mesh Element size 12 mm TEC|ODM Mesh Element size 4 mm
TEC|ODM Mesh Element size 6 mm
© 2005 Copyright by DYNAmore GmbH
Modellierung 4. LS-DYNA Anwenderforum, Bamberg 2005
I - I - 36
Simple box crash experiment:Box section 50 mm x 80 x 500mm, t= 1.0mm, mild steel
Varied parameters:
average edge length 15/10/5/2,5mmmesh orientation 0deg/ 25degdifferent mesh/ integration method: Belytschko-Tsay/ Fully IntegrationVaried number of spotweldsWith and without mapping or stamping dataRenumbering and move in space
Objective:
Is the result depending on the element length?
Is the result depending on the element orientation?
How does mapping influence/stabalise the results?
How do small changes in the input influence the results?
FE Experiments with varied parameters
v10_1: 10mm mesh, 0degmax internal energy 6766Nmmmax displacement 278mm
analysis: defomation plots
FE Experiments with varied parameters
© 2005 Copyright by DYNAmore GmbH
4. LS-DYNA Anwenderforum, Bamberg 2005 Modellierung
I - I - 37
V10_1n: 10mm mesh, 0 deg, full integrationmax internal energy 6499Nmmmax displacement 241mm
analysis: defomation plots
FE Experiments with varied parameters
v10_2: 10mm mesh, 25degmax internal energy 6439Nmmmax displacement 295mm
analysis: defomation plots
FE Experiments with varied parameters
© 2005 Copyright by DYNAmore GmbH
Modellierung 4. LS-DYNA Anwenderforum, Bamberg 2005
I - I - 38
V10_2n: 10mm mesh, 25 deg, full integrationmax internal energy 6272Nmmmax displacement 286mm
analysis: defomation plots
FE Experiments with varied parameters
v10_3: 10mm triangle meshmax internal energy 6428Nmmmax displacement 215mm
analysis: defomation plots
FE Experiments with varied parameters
© 2005 Copyright by DYNAmore GmbH
4. LS-DYNA Anwenderforum, Bamberg 2005 Modellierung
I - I - 39
v10_4: 10mm mesh, 25deg, more spotweldmax internal energy 6560Nmmmax displacement 265mm
analysis: defomation plots
FE Experiments with varied parameters
V10_4n: 10mm mesh, 25 deg, more spotweld, full integrationmax internal energy 6741Nmmmax displacement 295mm
analysis: defomation plots
FE Experiments with varied parameters
© 2005 Copyright by DYNAmore GmbH
Modellierung 4. LS-DYNA Anwenderforum, Bamberg 2005
I - I - 40
v10_5: 10mm mesh, 0 deg, more spotweldmax internal energy 6565Nmmmax displacement 262mm
analysis: defomation plots
FE Experiments with varied parameters
v10_6: 10mm mesh, 0deg mapped stamping data MpCCI
max internal energy 6658Nmmmax displacement 235mm
analysis: defomation plots
FE Experiments with varied parameters
© 2005 Copyright by DYNAmore GmbH
4. LS-DYNA Anwenderforum, Bamberg 2005 Modellierung
I - I - 41
v10_7: 10mm mesh, 25deg mapped stamping data MpCCI
max internal energy 6350Nmmmax displacement 243mm
analysis: defomation plots
FE Experiments with varied parameters
v10_6n: 10mm mesh, 0deg mapped stamping data DYNAIN
max internal energy 6468Nmmmax displacement 250mm
analysis: defomation plots
FE Experiments with varied parameters
© 2005 Copyright by DYNAmore GmbH
Modellierung 4. LS-DYNA Anwenderforum, Bamberg 2005
I - I - 42
v10_7n: 10mm mesh, 25deg mapped stamping data DYNAIN
max internal energy 6376Nmmmax displacement 233mm
analysis: defomation plots
FE Experiments with varied parameters
Analysis: comparison of Displacement10mm meshing
0,00E+00
5,00E+01
1,00E+02
1,50E+02
2,00E+02
2,50E+02
3,00E+02
3,50E+02
0,00
5,00
10,0
0
15,0
0
20,0
0
25,0
0
30,0
0
35,0
0
40,0
0
45,0
0
50,0
0
55,0
0
60,0
0
65,0
0
70,0
0
75,0
0
80,0
0
85,0
0
90,0
0
95,0
0
100,
00
Time [ms]
Dis
plac
emen
t [m
m]
10_1 max 279,7910_2 max 294,5610_3 max 215,1610_4 max 265,3010_5 max 262,4710_6 max 227,1010_6n max 250,6310_7 max 302,0810_7n max 232,63
FE Experiments with varied parameters
© 2005 Copyright by DYNAmore GmbH
4. LS-DYNA Anwenderforum, Bamberg 2005 Modellierung
I - I - 43
v5_1: 5mm mesh, 0degmax internal energy 6398Nmmmax displacement 296mm
analysis: defomation plots
FE Experiments with varied parameters
V5_1n: 5mm mesh, 0 deg, full integrationmax internal energy 6481Nmmmax displacement 277mm
analysis: defomation plots
FE Experiments with varied parameters
© 2005 Copyright by DYNAmore GmbH
Modellierung 4. LS-DYNA Anwenderforum, Bamberg 2005
I - I - 44
v5_5: 5 mm mesh, 0 deg, more spotweldmax internal energy 6466Nmmmax displacement 295mm
analysis: defomation plots
FE Experiments with varied parameters
v5_2: 5mm mesh, 25degmax internal energy 6363Nmmmax displacement 278mm
analysis: defomation plots
FE Experiments with varied parameters
© 2005 Copyright by DYNAmore GmbH
4. LS-DYNA Anwenderforum, Bamberg 2005 Modellierung
I - I - 45
v5_3: 5mm triangle meshmax internal energy 6425Nmmmax displacement 265mm
analysis: defomation plots
FE Experiments with varied parameters
V5_4: 5mm mesh, 25deg, more spotweldmax internal energy 6327Nmmmax displacement 277mm
analysis: defomation plots
FE Experiments with varied parameters
© 2005 Copyright by DYNAmore GmbH
Modellierung 4. LS-DYNA Anwenderforum, Bamberg 2005
I - I - 46
v5_6: 5mm mesh, 0deg mapped stamping data MpCCI
max internal energy 6401Nmmmax displacement 268mm
analysis: defomation plots
FE Experiments with varied parameters
v5_7: 5mm mesh, 25deg mapped stamping data MpCCI
max internal energy 6593Nmmmax displacement 278mm
analysis: defomation plots
FE Experiments with varied parameters
© 2005 Copyright by DYNAmore GmbH
4. LS-DYNA Anwenderforum, Bamberg 2005 Modellierung
I - I - 47
v5_6n: 5mm mesh, 0deg mapped stamping data DYNAIN
max internal energy 6346Nmmmax displacement 268mm
analysis: defomation plots
FE Experiments with varied parameters
v5_7n: 5mm mesh, 25deg mapped stamping data DYNAIN
max internal energy 6323Nmmmax displacement 278mm
analysis: defomation plots
FE Experiments with varied parameters
© 2005 Copyright by DYNAmore GmbH
Modellierung 4. LS-DYNA Anwenderforum, Bamberg 2005
I - I - 48
Analysis: comparison of Displacement5mm meshing
0,00E+00
5,00E+01
1,00E+02
1,50E+02
2,00E+02
2,50E+02
3,00E+02
3,50E+02
0,00
5,0010
,0015
,0020
,0025
,0030
,0035
,0040
,0045
,0050
,0055
,0060
,0065
,0070
,0075
,0080
,0085
,0090
,0095
,00
100,0
0
Time [ms]
Dis
plac
emen
t [m
m] 5_1 max 295,75
5_1n max 276,585_2 max 278,375_3 max 264,945_4 max 276,875_5 max 295,215_6 max 269,775_6n max 267,515_7 max 276,485_7n max 277,82
FE Experiments with varied parameters
v2.5_1: 2.5mm mesh, 0degmax internal energy 6398Nmmmax displacement 296mm
analysis: defomation plots
FE Experiments with varied parameters
© 2005 Copyright by DYNAmore GmbH
4. LS-DYNA Anwenderforum, Bamberg 2005 Modellierung
I - I - 49
V2-5_1n: 2.5 mm mesh, 0 deg, full integrationmax internal energy 6439Nmmmax displacement 291mm
analysis: defomation plots
FE Experiments with varied parameters
V2-5_5: 2.5 mm mesh, 0 deg, more spotweldmax internal energy 6423Nmmmax displacement 289mm
analysis: defomation plots
FE Experiments with varied parameters
© 2005 Copyright by DYNAmore GmbH
Modellierung 4. LS-DYNA Anwenderforum, Bamberg 2005
I - I - 50
V2-5_2n: 2.5 mm mesh, 25 degmax internal energy 6471Nmmmax displacement 287mm
analysis: defomation plots
FE Experiments with varied parameters
v2.5_3: 2.5mm triangle meshmax internal energy 6448Nmmmax displacement 279mm
analysis: defomation plots
FE Experiments with varied parameters
© 2005 Copyright by DYNAmore GmbH
4. LS-DYNA Anwenderforum, Bamberg 2005 Modellierung
I - I - 51
Analysis: comparison of Displacement2.5mm meshing
0,00E+00
5,00E+01
1,00E+02
1,50E+02
2,00E+02
2,50E+02
3,00E+02
3,50E+02
0,005,00
10,0015,00
20,0025,00
30,0035,00
40,0045,00
50,0055,00
60,0065,00
70,0075,00
80,0085,00
90,0095,00
100,00
Time [ms]
Dis
plac
emen
t [m
m]
2.5_1 max 297,532.5_1n max 290,502.5_2n max 287,302.5_3 max 278,792.5_5 max 288,752.5_6 max 293,742.5_6n max 297,342.5_7 max 282,872.5_7n max 311,40
FE Experiments with varied parameters
V2-5_4n: 2.5 mm mesh, 25 deg, more spotweldmax internal energy 6477Nmmmax displacement 280mm
analysis: defomation plots
FE Experiments with varied parameters
© 2005 Copyright by DYNAmore GmbH
Modellierung 4. LS-DYNA Anwenderforum, Bamberg 2005
I - I - 52
v2.5_6: 2.5mm mesh, 0deg mapped stamping data MpCCI
max internal energy 63412Nmmmax displacement 293mm
analysis: defomation plots
FE Experiments with varied parameters
v2.5_7: 2.5mm mesh, 25deg mapped stamping data MpCCI
max internal energy 6416Nmmmax displacement 285mm
analysis: defomation plots
FE Experiments with varied parameters
© 2005 Copyright by DYNAmore GmbH
4. LS-DYNA Anwenderforum, Bamberg 2005 Modellierung
I - I - 53
v2.5_6n: 2.5mm mesh, 0deg DYNAINmax internal energy 6360Nmmmax displacement 297mm
analysis: defomation plots
FE Experiments with varied parameters
v2.5_7n: 2.5mm mesh, 25deg DYNAINmax internal energy 6392Nmmmax displacement 311mm
analysis: defomation plots
FE Experiments with varied parameters
© 2005 Copyright by DYNAmore GmbH
Modellierung 4. LS-DYNA Anwenderforum, Bamberg 2005
I - I - 54
Analysis: Comparison max. displacement
Compression is nearly independent from the element length in a range from 10mm to 2.5 mm for the same element orientation
0
25
50
75
100
125
150
175
200
225
250
275
300
325
350
375
400
0 1 2 3 4 5 6 7 8 9 10 11 12
average element length [m m]
max
dis
plac
emen
t [m
m]
c
Analysis of Results/ Conclusion
Analysis: Comparison max. displacement
The max displacement difference for 0° mesh and 25° mesh is small for finer meshes and big for coarser meshes
0
2
4
6
8
10
12
14
16
18
20
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
averag e element leng t h [ mm]
cc
Analysis of Results/ Conclusion
© 2005 Copyright by DYNAmore GmbH
4. LS-DYNA Anwenderforum, Bamberg 2005 Modellierung
I - I - 55
Analysis: Influence on mesh translation and reumbering
For 10 mm the variation is about 8mm where as the deviation for smaller elements sizes is about 3mm for the same element orientation
Analysis of Results/ Conclusion
150 00
200,00
250,00
300,00
350,00
3.5_1 max 289,053.5_1_ren max 289,053.5_1_dis max 286,293.5_1_ren max 288,70
200,00
250,00
300,00
350,00
2_1 max 290,092_1_ren max 290,092_1_dis max 293,09
150,00
200,00
250,00
300,00
10_1 max 279,7910_1_ren max 271,6410_1_dis max 278,53
Analysis: Influence on results of very small elements.
For 1,25 mm the BT (typ2) element seems to be to weak. For smaller elements sizes, full integration seems to have better results.
Analysis of Results/ Conclusion
C o m p a r is o n o f F u l l In t e g r a t io n
0 ,0 0 E + 0 0
5 ,0 0 E + 0 1
1 ,0 0 E + 0 2
1 ,5 0 E + 0 2
2 ,0 0 E + 0 2
2 ,5 0 E + 0 2
3 ,0 0 E + 0 2
3 ,5 0 E + 0 2
0,00
6,00
12,00
18,00
24,00
30,00
36,00
42,00
48,00
54,00
60,00
66,00
72,00
78,00
84,00
90,00
96,00
T im e [m s ]
Dis
plac
emen
t [m
m]
2 .5 _ 1 n m a x 2 9 0 ,5 02 _ 1 n m a x 2 8 2 ,7 31 .2 5 _ 1 n m a x 2 9 6 ,7 8
C o m p a r is o n o f B T
0 ,0 0 E + 0 0
5 ,0 0 E + 0 1
1 ,0 0 E + 0 2
1 ,5 0 E + 0 2
2 ,0 0 E + 0 2
2 ,5 0 E + 0 2
3 ,0 0 E + 0 2
3 ,5 0 E + 0 2
0,00
5,00
10,0
0
15,0
0
20,0
0
25,0
0
30,0
0
35,0
0
40,0
0
45,0
0
50,0
0
55,0
0
60,0
0
65,0
0
70,0
0
75,0
0
80,0
0
85,0
0
90,0
0
95,0
0
100,
00
T im e [m s ]
Dis
plac
emen
t [m
m]
2 .5 _ 1 m a x 2 9 7 ,5 32 _ 1 m a x 2 9 0 ,0 91 .2 5 _ 1 m a x 3 0 3 ,9 2
© 2005 Copyright by DYNAmore GmbH
Modellierung 4. LS-DYNA Anwenderforum, Bamberg 2005
I - I - 56
Analysis: comparison max displacement variation
Analysis of Results/ Conclusion
variation for different mesh sizes
150
170
190
210
230
250
270
290
310
1 2 3 4 5 6 7 8 9
run
dis
pl.
(mm) 10mm
5 mm
2.5 mm
Analysis: Comparison of integration method
Calculation Time
CPU Time [s]
0,00E+00
2,00E+03
4,00E+03
6,00E+03
8,00E+03
1,00E+04
1,20E+04
1,40E+04
1,60E+04
1,80E+04
10_1
/10_1
n
10_2
/10_2
n
10_4
/10_4
n
5_1/5
_1n
5_2/5
_2n
5_4/5
_4n
2.5_1
/2.5_
1n
2.5_2
/2.5_
2n
2.5_4
/2.5_
4n
Belytschko-TsayFully Integration
Analysis of Results/ Conclusion
© 2005 Copyright by DYNAmore GmbH
4. LS-DYNA Anwenderforum, Bamberg 2005 Modellierung
I - I - 57
Results
Results for the displacement and the internal energy seem to be smooth and stable in a range from 15mm to 2,5 mm for orthogonal element orientation
Different element orientation give different results for coarser meshes
Finer mesh is not so sensitive for different element orientation, integration method, number of spotwelds, mapping, small changes in the input (renumbering, moving the model in space)
Mapping tools are easy to use for Crash coupling. The influence of the mapping was getting smaller for smaller element sizes for the influenced zone was getting smaller and the crash mode was very stable in our example.
Analysis of Results/ Conclusion
Conclusion
If you know the collapse mode of a part you can use a coarse mesh which should be orthogonal in the collapse direction (so you can achieve “superconvergence”)
If you doesn't know the collapse mode of a part; Please use finer meshes
No one knows the exact collapse mode of all the parts in a vehicle!
Meshing rules for orthogonal /Mapping/Integration schemes meshes are important for coarser meshes but not important for finer meshes.
Creation of finer meshes can be automated by TEC|ODM!
Analysis of Results/ Conclusion
© 2005 Copyright by DYNAmore GmbH
Modellierung 4. LS-DYNA Anwenderforum, Bamberg 2005
I - I - 58
Outlook
The crashbox sample will be applied to a complete vehicle to find out about the time saving potential and the influence on the results.
Analysis of Results/ Outlook
Thank you for your attention!Please ask some questions
© 2005 Copyright by DYNAmore GmbH
4. LS-DYNA Anwenderforum, Bamberg 2005 Modellierung
I - I - 59
© 2005 Copyright by DYNAmore GmbH
Modellierung 4. LS-DYNA Anwenderforum, Bamberg 2005
I - I - 60