radioss multi-domain – innovative simulation technique for cpu time efficient prediction of...

7th European Altair Technology ConferenceMunich / June 24-26, 2014

Radioss Multi-Domain – Innovative Simulation Technique for CPU Time efficient Prediction of Material Failure in Full Vehicle Crash Simulations

Aleksandar Bach (Ford Research and Advanced Engineering Europe)Hüseyin Cakir

Vincent Dampure (Altair Engineering GmbH)

7th European ATC / Munich / June 24-26, 2014A. Bach, H. Cakir (Ford), V. Dampure (Altair)

Contents

� Motivation

� Radioss Multi-Domain Approach

� Validation + Examples

� Summary

2


Motivation: Standard vs. refined Mesh 3

�� Accurate prediction with refined mesh only

Discplacement [mm]

Imp

ac

tor

Fo

rce

CAE_STANDARD

CAE_REFINED

TEST


Motivation 4

� Accurate prediction of crash events requires increased model complexity

o Local mesh refinement (shell / solid elements)

o Advanced material models incl. failure criteria

� Increase of model size + reduction of explicit time step

�� Increase of total CPU time beyond acceptable range of industrial applications

Objectives of RADIOSS Multi-Domain approach

Improve CPU time efficiency by maintaining the accuracy (compared to standard Mono-Domain approach)

test

CAE


Contents

� Motivation



� Summary

5


What is Multi-Domain 6

� Split global model into physically equivalent “sub-domains”

� Each domain using its own time step (tF » tS)

� Force and momentum transfers between domains will be calculated by a separate program (RAD2RAD)

RAD2RAD

full domain (tF) sub-domain (tS)

full fullexplicit time step t

tF: full domain

tS: sub-domain


Pre-Processing / Model Set-up 7

� User-friendly environment � single input file format (since Radioss V11.0.201)

- Define parts to be treated as sub-domain

- Define additional engine file per sub-domain

- Define cross contact between full domain and sub-domain

� Possible links between domains

- Common nodes

- Kinematic condition (/INTER/TYPE2: non-conforming meshes, beam2shell or solid2shell connections)

- General contact (/INTER/TYPE7, 11, 18, 24, …)


Multi-Domain will be efficient if … 8

Minimize communication between domains

� Size of sub-domain is less than 30% of full domain (nodes/elements)

� Time step ratio between full domain and sub-domain ≥ 3

� Keep cross contact between full and sub-domain as small as possible

Minimize size of cross contact

� Use only segments of full domain which are potentially impacting parts of sub-domain (manual work)

� Development of automated contact optimization urgently needed (development ongoing)


Parallelization of Multi-Domain Architecture 9

� No benefit of previous Multi-Domain release with more CPUs

� Due to parallelization of RAD2RAD process the performance of current Multi-Domain release was significantly improved


Contents

� Motivation



� Summary

10


Method Development / Validation Procedure 11

COUPON

LEVELCOMPONENT

LEVEL

FULL VEHICLE

LEVEL

SYSTEMATIC VALIDATION PROCEDURE

� New CAE methodologies have to be checked by systematic

validation procedure in order to guarantee accuracy and robustness

of application for further industrial use


Example: Coupon Level 12

source: Research project FOSTA/AVIF Nr. P 806/06/2009 / A262 / S24 / 10162/08

Frauenhofer (IWM)

material properties

tensile test / 22MnB5 sample

� Metallurgical notch is significantly impacting

the crash performance


Example: Coupon Level / Multi-Domain vs. Mono-Domain 13

test data by Frauenhofer (IWM)

CAE Model

CAE vs. Test

� CAE correlates well with

test data

� No differences between

Multi-Domain and Mono-

Domain simulation

sub-domainfull domain


Example: Component Level 14

3PB of 22MnB5 beam

� Geometrical notch is significantly impacting the crash performance


Example: Component Level 15

CAE vs. Test

� Coarse mesh is not able to predict material failure correctly

� Fine mesh correlates perfectly with test data

� No differences between Multi-Domain and Mono-Domain simulation

coarse mesh (7mm)

fine mesh (1mm)


Example: Full Vehicle Level 16

full domain sub-domain with detailed SW

model (incl. HAZ)

side impact / run with 48 CPUs full vehicle crash model

number of elements ~ 2 millions

element ratio: sub-domain / full domain ~ 4%

time step ratio: full domain / sub-domain 2


Example: Full Vehicle Level / Multi-Domain vs. Mono-Domain

time time

en

erg

ies

intr

usio

n

17

global energies intrusion (@ B-pillar lower)

� The results are comparable for the Multi-Domain and

Mono-Domain simulation


Example: Full Vehicle Level / Run Time 18

„Multi-Domain #1sub-domain in global contact

side impact Mono-Domain Multi-Domain #1global contact

Multi-Domain #2cross contact

run time [h] ~ 27 ~ 100 ~ 15

Multi-Domain #2sub-domain in cross contact

slow-down 3.7 speed-up

1.8� For efficiency reasons it is

essential to optimize the contact between the sub-domain and full domain

� Automated routine urgently required (development ongoing)

major

improvement


Example: Full Vehicle Level / Further CPU Benchmarks 19

case number of

elements

element ratiosub- / full domain

time step ratiofull / sub-domain

Speed-upMulti-/Mono

0.5 m 4% 4 3

1.2 m 2% 3 4

2.3 m 5% 4.4 / 10 3 / 4

0.35 m 20% 5 2

1.5 m 5% 7 6

� CPU speed-up highly depending on modeling conditions

(ratio of elements and time step, size of cross contact)


Summary 20

� The Multi-Domain simulation approach is very important for Ford

� Multi-Domain is available and in use on Ford high performance computing cluster, improvements regardinguser friendliness and performance were achieved

� Benchmarks on full vehicle level are showing promising potential of CPU time reduction at increased computing accuracy

Next Steps

� Optimization of cross contact

� Automated mesh refinement of critical parts and part replacement in full vehicle model

radioss multi-domain – innovative simulation technique for cpu time efficient prediction of...

Engineering

domain tf

domain ts

domain release

domain architecture

domain approach validation

cakir ford

european atc munich

mono domain simulation