Engineering Center Steyr GmbH & Co KG Adams User Meeting 2011 Hocheffiziente Berücksichtigung des Fügestellenkontaktes von FEM-Modellen in Adams

Transcription

1 Engineering Center Steyr GmbH & Co KG Adams User Meeting 2011 Hocheffiziente Berücksichtigung des Fügestellenkontaktes von FEM-Modellen in Adams M. Breitfuss

2 Joints everywhere? How to handle them... Joints are common in technical structures Joints show nonlinear behavior Local non linearity has global influence Challenge for conventional simulation Direct FEM causes high computational effort Modal approach leads to moderate accuracy New method developed by ECS Highly efficient simulation of jointed structures Contact consideration during MBS simulation 2

3 A generic example FEM structure Two solid substructures Bolted connection elements and nodes Boundary condition and loads Fixed with respect to ground Bolt pretension Force at free end of beam substructure 3

4 Classic mode base used for model reduction Method according to Craig and Bampton Constraint modes (CM) and according transformation matrix ψ CM I ψ cb, ci, Fixed boundary normal modes (FBNM) and according transformation matrix Φ FBNM 0 Φ nb, ni, 4

5 Extended mode base used for jointed structures Method developed by ECS Joint interface modes (JIM) and according transformation matrix ψ JIM 0 ψ JIM, b JIM, i Classic mode base Extended mode base x I 0 ψ cb, nb, Φ ci, n, i q classic x I 0 0 cb, n, b JIM, b ψ Φ ψ ci, n, i JIM, i q extended Contact modes (joint interface modes) 5

6 Good convergence with respect to number of JIM Normal stresses due to applied load MAMBA subroutine for contact 0 JIM 10 JIM 25 JIM 50 JIM FEM reference solution 6

7 Dynamic simulation Flexible structure 12 constraint modes, 25 fixed boundary normal modes 50 joint interface modes MBS simulation Free vibration of the initially deflected beam 7

8 Basic FEM MBS fatigue assessment Modal approach for fatigue assessment Hybrid MBS Model (rigid parts and flexible structures) Flexible structures without joint contact MBS Model Simulation using MSC Adams Fatigue Assessment using FEMFAT Flexible Structure using MSC Nastran FEM Model 8

9 Advanced FEM MBS fatigue assessment Modal approach considering nonlinear joint behavior Subroutine for Contact MBS Model Simulation using MSC Adams Fatigue Assessment using FEMFAT Flexible Structure using MSC Nastran Script based contact surface detection Computation of JIMs FEM Model 9

10 Advanced FEM MBS fatigue assessment Simulation Process Data Flow Mode Shapes 1 2 n Flexible Structure using MSC Nastran and Mamba MBS Simulation using MSC Adams and MAMBA Subroutine (Co - Simulation) Modal Coordinates q 1 (t) q 2 (t) q n (t) MSC Adams Data Export Channel 1 q 1 (t) 1 Channel 2 q 2 (t) 2 Modal Stresses 1 2 n MSC Nastran op2-file Channel n q n (t) n Additional Load Cases (Pretension,...) 10

11 Truck door slam, an industrial application FEM structure Spot welded seams modeled using FEMFAT nuggets elements and nodes Spot weld seams Test scenario Door slams with 2 m/sec into latch mechanism Durability performance evaluation of door structure Circumferential folded flange Stiffener 11

12 Dynamic simulation Flexible structure 18 constraint modes 35 fixed boundary normal modes 125 joint interface modes MBS Simulation Contact consideration Friction and door sealing is neglected Hinge and latch mechanism are represented by constraints 12

13 Contact influences damage distribution Hinge area without contact consideration with contact consideration Different damage values Different damage distribution 13

14 Contact influences damage distribution Window area Most damaged spot weld with contact consideration without contact consideration Significant differences in spot weld damage distribution 14

15 125 JIMs Adams User Meeting 2011 Low computational effort CPU Time Truck door slam: preprocessing CPU time in minutes Contactsurface detection using MAMBA Contact surface evaluation using MSC Nastran Flexible structure generation using MSC Nastran HP rx1620 server used to run Nastran Intel Core 2 / 2.66 Ghz workstation used to run Adams and MAMBA 15

16 FEM MBS Adams User Meeting 2011 Low computational effort CPU Time Truck door slam: dynamic simulation CPU time in minutes 15 MBS simulation using MSC Adams and MAMBA Direct FEM simulation more than 1 day HP rx1620 server used to run Nastran Intel Core 2 / 2.66 Ghz workstation used to run Adams and MAMBA 16

17 Crank drive dynamics, an industrial application Fretting corrosion Observed at test rig Which revolution speed range is critical? Crankshaft Torsional vibration damper (TVD) Wear pattern at flange 17

18 Dynamic Simulation Static loadcase Bolt pretension MAMBA with 75 JIM FEM Full engine run up simulation Consideration of crank drive dynamics Nonlinear contact at flange 18

19 Evaluation of joint region One working period at 3000 rpm Large changes of contact pressure values These areas correlate with fretting corrosion Gaping Contact pressure distribution 19

20 Conclusion and Outlook Highly efficient consideration of contact Extended joint mode base Contact based on penalty approach Preprocessing module for contact definition Dynamic analyses with long time series Next steps Full body in white fatigue assessment Dry friction formulation 20