A dvanced Simulation Techniques for the coupled Fatigue and NVH Optimization of Engines.

1. Advanced Simulation Techniques for the coupled Fatigue and NVH Optimization of Engines. K+P Software, Schönbrunngasse 24, A - 8043 Graz / Austria Tel.: 0043/316/328251, Fax: 0043/316/328351 E-Mail: office@kplusp.com

2. 1 Introduction n Environmental Pollution increasing government regulations concerning the emissions of vehicles (air pollution and noise ...) Limited Ressources n oil and raw material consumption ... Customer Requirements n oil consumption, sound engineering ... Tasks for the Automotive Industry n à reduce vehicle weights and oilconsumption optimize NVH Behaviour and create specific sounds à à convenient numerical simulation tools (FEM ...) can help to - analyze and optimize structures in the very first development stage - reduce time and costs required for prototyping - avoid numerous test series

3. 2 Fatigue analysis of crankshafts State-of-the-Art n Linear static finite element analyses of à single crank throws Loading cases, maximum gas load‘, à ,maximum mass force‘ and ,maximum torque‘ Nonlinear dynamic analysis n Linear static analyses however do not enable the consideration of actual à dynamic effects, such as the nonlinearities (time dependencies) of mass-, stiffness- and damping ¡ matrices the statically undetermined supporting of the rotating crankshaft ¡ gyroscopic effects (flywheel wobbling ...) ¡ hydrodynamic conditions in the bearings ... ¡

4. 3 Nonlinear dynamic analysis of crankshafts Flow Chart Flow Chart n n

5. 4 Example: ,Nonlinear fatigue analysis of a 4-cylinder-inline crankshaft‘ n Beam-Mass-Model, perfect correlation ¡ between analysis and measurement results Solid-Element-Model, time ¡ dependent stress distribution due to the 3-dimensional vibration behaviour of the powertrain, momentary views

6. 5 Example: ,Nonlinear fatigue analysis of a 6-cylinder-boxer crankshaft‘ n Time dependent stress distribution, ¡ momentary view Safety factors versus engine ¡ speed, influenced by a resonance effect caused by flywheel wobbling

7. 6 Example: ,Nonlinear fatigue analysis of a Two-Mass-Flywheel‘ n Flywheel wobbling, momentary view ¡ Time dependent stress ¡ distribution in the transfer mechanism due to flywheel wobbling, momentary views

8. 7 Example: ‚Nonlinear dynamic analysis of a Crankshaft-Starter-Generator‘ n ¡ Finite-Element-Models Crankshaft with Flywheel/CSG-Rotor CSG-Stator

9. 8 Example: ‚Nonlinear dynamic analysis of a Crankshaft-Starter-Generator‘ n ¡ 3.000 RPM ,Full Load‘, Operating temperature 90° Air gap distribution and electromotive forces between Rotor and Stator versus circumference and crank angle, influenced by flywheel wobbling Air gap distribution Electromotive forces

10. 9 Fatigue and NVH analyses of engines n State-of-the-art à Fatigue assessments of engines usually are done based on the linear static analysis of subdomains (deformation behaviour of single main bearing walls ...) à Furthermore linear analysis in the frequency domain are state-of-the-art for NVH assessments (determination of transfer functions ...) n Nonlinear dynamic analyses à Actual dynamic effects and excitation mechanisms however can have a dominant influence on both the fatigue and the NVH behaviour of engines à Nonlinear analyses in the time domain are unavoidable to enable a convenient consideration of those effects, such as the nonlinearities (time dependencies) of mass-, stiffness- and damping ¡ matrices statically undetermined supported, rotating shafts (crankshaft, balancing ¡ shafts ...) gyroscopic effects (flywheel wobbling ...) ¡ misalignment and excentric pressure distributions in the bearings ¡ resonance effects ¡ nonlinearities in toothings ... ¡

11. 10 Nonlinear fatigue and NVH analysis of engines n Flow Chart

12. 11 Nonlinear fatigue and NVH analysis of engines n Example: ,FE-Models for fatigue and NVH analyses‘

13. 12 Nonlinear NVH analysis of engines n Normal mode analysis à knowledge about the basic dynamic behaviour (identification of resonance effects, explanation of phenomena occuring at forcedvibration analysis ...)

14. 13 Example: ,Nonlinear NVH analysis of an n 4-cyl.-inline engine with balancing shafts‘ ¡ Flow chart for the iteration procedure between shaft dynamics and tooth backlashes / tooth forces

15. 14 Example: ‚Nonlinear NVH analysis of an 4-cyl.-inline engine with n balancing shafts‘ Equivalent System for the nonlinear analysis of the gear drive dynamics ¡

16. 15 Example: ‚Nonlinear NVH analysis of an 4-cyl.-inline engine with n balancing shafts‘ 3.000 RPM ,Full Load‘, Operating temperature 90° ¡ Tooth forces in the primary toothing

17. 16 Example: ‚Nonlinear NVH analysis of an 4-cyl.-inline engine with n balancing shafts‘ 3.000 RPM ,Full Load‘, Operating temperature 90° ¡ Reaction forces in the axial thrust bearing of the primary balancing shaft

18. 17 Example: ,Nonlinear NVH analysis of an 4-cyl.-inline engine with n balancing shafts‘ 3.000 RPM ,Full Load‘, Influence of different operating temperatures ¡ Integral velocity levels influenced by gear drive dynamics ,Room temperatur‘ 25° Operating temperature 90°

19. 18 Example: ‚Nonlinear NVH analysis of an 4-cyl.-inline engine with n balancing shafts‘ 3.000 RPM ,Full Load‘, Operating temperature 90° ¡ Integral Velocity Levels for the basic design and a design modification Basic design Design modification

20. 19 Example: ‚Nonlinear NVH analysis of an 4-cyl.-inline engine with n mechatronic actuators for a fully variable electromechanical valve train‘ Finite-Element-Model ¡

21. 20 Example: ‚Nonlinear NVH analysis of an 4-cyl.-inline engine with n mechatronic actuators for a fully variable electromechanical valve train‘ Time dependent vibration behaviour of an actuator, momentary views ¡

22. 21 Example: ‚Nonlinear NVH analysis of an 4-cyl.-inline engine with n mechatronic actuators for a fully variable electromechanical valve train‘ 3.000 RPM ,Full Load‘, Integral velocity levels before/after an ¡ optimization Design modification Basic design

23. 22 Nonlinear NVH analysis of engines n Further examples for actual excitation mechanisms Piston ¡ Piston side forces Piston slap

24. 23 Example: ‚Nonlinear fatigue analysis of an 4-cyl.-inline engine‘ n 5.000 RPM ,Full Load‘, time dependent stress distribution influenced by ¡ flywheel wobbling, momentary views

25. 24 n Conclusion à Linear static and dynamic finite element analysis can be a usable tool to achieve a basic knowledge about the fatigue behaviour of engine components and the NVH behaviour of complete power units à Both the stress distributions and the NVH behaviour however can be highly influenced by actual dynamic effects and excitation mechanisms (flywheel wobbling, clearances, resonance effects ...) Therefore nonlinear transient analysis are unavoidable to enable the à simulation results to be close to reality. Furthermore temperature dependencies (oil viscosity and clearances at different operating temperatures...) also have to be considered. à K+P‘s highly advanced simulation techniques (nonlinear dynamics ...) and enhanced algorithms for pre- and post-processing (automized mesh modification, advanced fatigue assessment ...) provide a powerful framework for analyses of ultimate quality and efficiency.