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Simulation Tool including failure for Structural Adhesives in Full-Car Crash Models

H. Lanzerath, Ford Research & Advanced Engineering Europe N. Nowack, Imperia Automotive Engineering E. Mestres, Altair Development France

EHTC Conference, September 30th 2008, Strasbourg

Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Overview

· · · · · · · · Why structural adhesives? Basic properties of structural adhesive Motivation for developing a new CAE method/crash Solution, development and result RADIOSS rupture interface definition Validation Summary and Outlook Acknowledgements

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Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Why structural adhesives?

Benefits of Structural Adhesives · Enable multimaterial designs · Enable downgauging of sheet metal structure · Improvement of attribute performance · Avoid local stress concentrations · Applicable in combination with mechanical joining techniques · Good dampening characteristics · Low heat input during assembly process · Sealing capability · Corrosion protection · .....

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Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Basic properties of structural adhesives

Tension Test

5 1/s 0.5 1/s

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Shear Test

Stress

0.05 1/s 0.005 1/s

Stress

shear damage/failure

Strain

Strain

· · ·

Thin connection between sheet metal (0.1 mm to 0.3 mm) Load dependant strain hardening and failure behavior Strain rate-dependant strain hardening and failure behavior

Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Motivation for developing a new CAE method

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· Advanced materials and joining technologies are more and more introduced in vehicle structures. · Upfront we want to better evaluate the benefits of adding structural adhesives for crash performance. · The most efficient way is to do that by CAE (crash simulation). · Up to know there is no efficient CAE method for crash available. · Ford R&A Europe developed and validated a new CAE method ("Interface"Method) and implemented it in close cooperation with Altair Engineering into the commercial crash code RADIOSS.

Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Request for a new crash simulation method

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Detailed FEM-model Adhesive bonding New Method requested ! · Time step too small · Millions of elements Applicable for full car CAE Not applicable for full car CAE

Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Boundary Conditions for a Full-Car Crash

· User friendly implementation for full car models · Less or no computational time increase · Acceptable results for weld bonding as well · Acceptable precision for design support on full car crash CAE level · Pre- and post-processing with standard tools · Availability for suppliers to ensure data exchange

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Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Possible CAE methods for adhesive

Spring type modelling methods + BIW sheet metal mid plane Adhesive springs = Contact to connect adhesive and sheet metal

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· Force based failure criteria High modelling effort, not efficient and accurate for full car crash

Adhesive brick element modelling methods + BIW sheet metal mid plane + BIW sheet metal mid plane Adhesive Adhesive with half of sheet metal

·User defined materials ·Drucker Prager material law = ·Cohesive elements e.g. Contact to connect *MAT_ARUP_ADHESIVE (LSadhesive and DYNA) sheet metal ·Gurson material Law ·.... = High modelling effort, user Offset contact to defined material not available at connect adhesive suppliers and sheet metal

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Research & Advanced Engineering

Preferred CAE methods for adhesive

Basic adhesive data

5 1/s 0.5 1/s 0.05 1/s 0.005 1/s

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+ BIW sheet metal mid plane

Virtual adhesive

Input

Adhesive contact modelling method

= Adhesive contact to connect sheet metal

Less modelling effort only one contact No solid element modelling necessary User friendly

Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Advantages adhesive contact modeling

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Flange gap of 0.85mm +/- 0.15mm between both parts Variation because of · Element size · CAE modelling approximation to CAD geometry · Combination of parts from different engineers

Advantages Relative displacement criteria independent form gap variation Slave definition defines the size of the adhesive contact area

Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Development time line

Q1/2005 - Q1/2006 Q3/2006 ­ Q1/2008 Q2/2008

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Development of 1st reduced interface

Start of cooperation between

Further improvement of rupture interface

Successful finishing of interface development for RADIOSS explicit

Based on RADIOSS Type2 Stress failure criteria Infinite interface stiffness

&

Interface deformation Displacement failure criteria Separated pre- and post failure routine

Available failure displacements Available maximum stresses Stress rate options

Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Interface surface definition

· Based on standard RADIOSS Type 2 interface · Master surface defined by faces · Slave surface defined by nodes and calculated by connected element area

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Abstract upper flange detail

Node Element

· Corresponding surface of node · Initially calculated · Depends on number of elements a node belongs to

Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Interface failure definition

· Based on displacements · Normal dnmax and tangential dtmax maximum displacement · Rupture criteria Rupt = 1 (dependent rupture criteria) IF:

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d 2 d 2 n + t 1 d n max d t max

= True, then failure

Stress behaviour defined by stress-displacement functions stress Necessary: max > 0 for d=0

relative displacement d

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Research & Advanced Engineering

Resulting stress failure based on input

Input 1 normal Input 1 tangential Input 2 normal Input 2 tangential Input 3 normal Input 3 tangential

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normal Stress

Max. normal displacement

Three input variants

Dependent failure criteria

-1. 0 0

tangential Displacement

0 2 .0

-1. 00

Max. tangential displacement

Max. normal stress

0 1 .0

0 0 .0 -0 0 8 . -0 4 .0 0 0 .0 0 4 .0 008 .

-0 1 .0

-0 2 .0

Max shear stress [kN/mm²] Max. tangential stress Resulting stress failure criteria

Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Adhesive interface result

New RADIOSS rupture interface card

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#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----| /INTER/TYPE2/1 Glue_with_Type2 # Slav_id Surf_id Spotflag Level Isearch Idel Dsearch 54 55 20 0 0 0 0 # Mode Ifltr SR_fun SN_fun ST_fun Idebug Max_Disp_N Max_Disp_T 1 0 0 200 201 0 1.00 1.00 # Stress_scale Str_rate_scale Disp_scale Alpha 1.0 1.0 1.0 0.0 /GRNOD/PART/54 Test_1 1 /SURF/PART/55 Test_2 Dummy input parameters 2 #---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

}

Added input

Use as standard RADIOSS Type 2 interface

Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Validation overview

The new RADIOSS rupture interface is validated on following load cases: Load case complexity Quasi static One element KSII specimen Torsion test Cantilever test Hat-profile test Dynamic Rear end substructure

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Full car test

Theoretical load case

Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Cantilever test

New FORD t-joint design for investigation on joining connections Connection between horizontal and vertical profile by adhesive rupture interface (not viewable)

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Top Left

Right Bottom

Joining specification for sub load case "Shear" x

Left Right

Not connected Bonded Spot weld

y

z

Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Results cantilever test

Shear flanges bonded Shear flanges weld bonded

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Force

Force

Test "080077" "080078" Test "080079" Test Simulation radi_rupti run12 config23

"080095" Test radi_rupti run13 config25 Simulation

Deformation CAE model is well fitted to test results

Deformation

One used RADIOSS rupture interface dataset for all load cases of validation process

Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Rear end substructure test

· Subassemblies rigidly attached to barrier · Sled uploaded to 282 kg, speed controlled to 11 m/s kinetic energy representative for rear crash Tests performed on sled test facility in FORD`s Technical Development Center Cologne Impactor: DOF: 011111 M= 282.00kg Vx= -11.0m/s

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Joining visualization of weld bonded specimen Bonded Spot weld Connection realized by new RADIOSS interface (not viewable)

Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Results rear end substructure

15ms 30ms 55ms

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Test average Radioss rupture interface

Force

Deformation

CAE model is well fitted to test results

One used RADIOSS rupture interface dataset for all load cases of validation process

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Research & Advanced Engineering

Full car test

CAE rear crash with spot weld or weld bonded connection

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Impactor M= 1250kg Vx= -22.22m/s

Adhesive bond lines represented by RADIOSS rupture interface z x y

Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Results full car test

Deformation of longitudinal rail Spot welds only

Calculation time 16CPUs [min] 200 150 100 50 0

Spot welds only Spot welds + Standard Type2 Spot welds + Rupture Interface

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126

125

126

Spot welds + Standard Type 2

Spot welds + Rupture Interface

Model type

Calculation time is kept constant Less time costs for modelling adhesive by contact interfaces One used RADIOSS rupture interface dataset for all load cases of validation process

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Research & Advanced Engineering

Summary and Outlook

· The RADIOSS rupture interface ... · contains most significant adhesive parameters · is user friendly (common to standard RADIOSS type2 interface) · is accurate and stable for several load cases · has nearly same calculation times as for models without adhesive

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· Such developments can only be done in close co-operation between OEMs and the software suppliers · The excellent co-operation during this project we would like to continue on other topics as well

Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

Acknowledgements

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We would like to thank Altair for the support, from technical and also from organizational site!

Thank you for your attention

Research & Advanced Engineering

30-Sep-2008 / ehtc_simulation_tool_including_failure_080908.ppt Advanced Materials CAE / H. Lanzerath, N. Nowack, E. Mestres

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Session06_Ford_Lanzerath

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