connection elements for joint representation
DESCRIPTION
For reliable full vehicle modelling taking numerous material properties and characteristics into account several boundary conditions need to be full filled. One particular material aspect is the consideration of failure events especially the failure of joint connections. On full vehicle level joint connections can be grouped by three types of connections: 0-D e.g. spot weld, 1-D e.g. weld line and 2-D e.g. bonded face. These types of connections attach in state of the art full vehicle models shell parts that represent the body structure of a vehicle model. Connection elements must form a suitable link between shell parts of a body structure and one possibility is to model them by using volume elements. Default continuum mechanics solid elements suffer on very small model time steps or on a significant mass increase caused by the Courant criteria. One solution is a special cohesive like connection element which considers only normal and tangential stress in connection direction and is independent from time step restrictions. The presentation will show an overview of the joint requirements on full vehicle level and the cohesive element calibration, validation and application on selected spot welded and bonded physical samples.TRANSCRIPT
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
N. Pasligh (Presenter), R. Schilling
Crash CAE:Connection elements for joint representation exemplarily spot welds
Crash CAE:Connection elements for joint representation exemplarily spot welds
6/11/20142
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
Motivation
6/11/20143
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
Generic b-pillar high overloading crash example
� Force displacement chart
a) Perfect world scenario without failure
b) Joint pattern #1 and failure consideration
c) Joint pattern #2 and failure consideration
d) No connection between b-pillar and side
structure
e) Sheet metal + joint failure with joint pattern #1
Joint failure need to be considered
� Reliability required
Displacement
Fo
rce
[%
of n
o f
ailu
re]
Generic example:
� Extreme overloading
� Simple CAE model (no trim)
� Coarse mesh
� Simplified sheet metal and spot weld
data
a
e
c
d
b
� Side structure and b-pillar
6/11/20144
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
Content
� Joint requirements
� Full vehicle CAE models
� History
� Joint environment
� Physical connections
� CAE connections
� Radioss solution and model approach
� Examples
6/11/20145
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
Joint requirements
6/11/20146
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
General joint requirements
� Automatic joint creation based on push button principle for different detail levels
� Full integration into HyperMesh, HyperCrash required
� Correlation between physical and numerical characteristics� Good theoretical approach for RADIOSS solver
� Tension, compression, shear, bending, torsional and mixed behavior treatment (load level, energy consumption, …)
� 3 to 4 sheet connection treatment
� Automatic post-processing in HyperView required � e. g. percentage to failure - tension, shear, mixed,
angle of mixed loading, current loading condition, …
Pre-processing
Processing
Post-processing
6/11/20147
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
Full vehicle CAE models
6/11/20148
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
Full vehicle model history
Past Future
Past model:
� Mesh size > 50 mm
� 30,000 elements
� No/ basic joint modelling
� …
Today’s model:
� Mesh size ~ 5 mm
� 2 - 5 million elements
� Joint modeling
� Implemented joint failure
criteria
� …
Future model:
� Mesh size > 1 mm
� Multi million elements
� More detailed joint modeling
� Complex, interactive failure
criteria
� …
M o d e l c o m p l e x i t y
6/11/20149
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
Examples of physical joining methods
Others
• Thermal (Laser
welding, brazing, …)
• Mechanical (Riveting,
screwing, …)
Example:
Spot welding Bonding
6/11/201410
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
Full vehicle joint environment
Detailed FEM-model
� Time step too small
� Millions of elements for joints
���� not applicable to full car CAE
model
Extracted mid surfaces
� Time step as full car model
� Few additional elements
���� Applicable for full car CAE
Transfer to full vehicle
6/11/201411
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
Type of joints
Common nodes Contacts Elements
1-D 2-D 3-D
Surface to surface
6/11/201412
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
RADIOSS solution and model approach
6/11/201413
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
x
y
z
σσσσxx
σσσσyy
ττττyx
ττττyz
ττττxy
ττττxz
Node 1 Node 2
Node 3
Node 5
Node 7Node 8
5.0 mm
Single 3-D joint element
shell
shell
Solid
H
• Considered element strength calculated
at integration points of mid surface
• Reference plane: mid surface with 4
integration points
• Element
height “H” can be zero
• Artificial
definition possible
� Connection methodology to connect shell mid surface layer
� Most important internal forces are considered at four integration points (allows
splitting forces into momentums)
� Element formulation is time step independent
σσσσzz
ττττzx
ττττzy
σσσσzz
ττττzx
ττττzy
Node 6
Continuum solid Cohesive solidvs.
3-D joint element example
� Details of 3-D element treatment
6/11/201414
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
� Modeling approach by cohesive /MAT/LAW59/ formulation in Radioss
/MAT/LAW59/59Connection element - D U M M Y -# Init. dens.
7.65E-6# E G
10.0 123.4# Nfunc Fsmooth Fcut Y_flag
1 1 0 0# Y_Func_N Y_Func_T Strain Rate ref. Yield stress Scale
1 2 0.00001 1/FAIL/CONNECT/59# EPS_N_MAX EXP_N ALPHA_N SR_N IFAIL ISOLID ISYM
1.0 2 1 0 1 1 1# EPS_T_MAX EXP_T ALPHA_T SR_T
10.0 2 1 0# EI_MAX
0/PROP/CONNECT/59Adhesive#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|/FUNCT/1Tensile curve# X Y
0 1.0000 1.0 1.0000
/FUNCT/2Shear curve# X Y
0 1.000 10.0 2.000
Shape parameter
Tensile strength vs. displacement
Shear strength vs. displacement
Failure displ.
Modulus data
Tension (mode I) Shear (mode II)
Joint material card
6/11/201415
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
� *1.rad file setting for MAT/LAW59
� /ANIM/BRICK/USR - variable settings for displacement based failure criteria
/ANIM/BRICK/USR3/1
/ANIM/BRICK/USR3/1
/ANIM/BRICK/USR5/1
Source: Altair Engineering GmbH, 2013
Joint post-processing
Tension (mode I) Shear (mode II)
6/11/201416
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
Joint material card modification
� Characterization of spot welds for full vehicle models
Shear load
Width = 0.5 “h”
He
igh
t “h
”
Ftension = 2 * Fshear
Width = “h”
Ftension = Fshear
Width = 1.5 “h”
Ftension = 0.67 * Fshear
Shear load Shear load
� True thickness flag � compensation of mesh dependent momentums
Re
su
ltin
g te
nsio
n lo
ad
6/11/201417
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
� Improvement of mixed mode treatment
Joint material card update ���� MAT/LAW83
30
°
60
°
α=1
α=0.1
α=-2α=-10
Influence of alpha parameter Influence of beta parameter
Source: V. Dampuré: Altair Engineering GmbH, 2014
6/11/201418
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
Meshing of joints
� Meshing proposals CAE
5.0 mm
Source: Altair Engineering GmbH, 2011
6/11/201419
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
Examples
6/11/201420
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
CAE design development support
Physical joining Full vehicle test
Validation: ComponentCalibration: Coupon Validation: Sub-system
5.0 mm
CAE concept Product development
6/11/201421
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
� Load case
Validation component
� CAE model
� Results
� Force-displacement chart of a component test example
Adhesive
Spot weld
6/11/201422
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
Validation sub-system
� CAE model� Load case
� Results
Adhesive
Spot weld
� Force-displacement chart of a sub-system test example
6/11/201423
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
Product development: Pre-processing
� Generation of joints
Pre-processingE. g. Fiesta � single parts
Source:
A. Hänschke
Source:
U. FoxScrew
Spot weld
Automatic model assembly
6/11/201424
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
� Full vehicle load case: examples
Processing
Product development: CAE crash analysis
Post-processing
6/11/201425
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
Summary
� Efficient pre-processing tools needed
� More efficient integration and fully automatic pre-processing
� Solve 3T and 4T dependency for multi layer joints
� Stable connection solving algorithm
� Stabilize element deletion and energy release rate handling
� Mixed load handling, joint interaction and mid surface gap treatment
� Fully supported and automatic visual/ tabulated/ … inspection of joints by post-processing tools
Connection elements are for developing a reliable crash CAE design
Thanks to Altair team for support! Special thanks to M. Bulla and V. Dampuré.
6/11/201426
© 2014 Ford Motor Company, All Rights Reserved
7th European Altair Technology Conference , June 24th - 26th 2014, MunichDr. Niels Pasligh (R&A Europe AMCAE), Dr. Robert Schilling (FoE)
Thank you very much for your attention!