Advanced Simulation Techniques for the coupled Fatigue and NVH Optimization of Engines. K+P Software, Schönbrunngasse 24, A Graz / Austria Tel.: 0043/316/328251, Fax: 0043/316/

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

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

Flow Chart Flow Chart Nonlinear dynamic analysis of crankshafts 3

 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 4 Example:,Nonlinear fatigue analysis of a 4-cylinder-inline crankshaft‘

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

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

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

 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 8 Example: ‚Nonlinear dynamic analysis of a Crankshaft-Starter-Generator‘

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

Flow Chart Nonlinear fatigue and NVH analysis of engines 10

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

Normal mode analysis  knowledge about the basic dynamic behaviour (identification of resonance effects, explanation of phenomena occuring at forced vibration analysis...) Nonlinear NVH analysis of engines 12

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

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

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

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

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

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

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

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

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

Further examples for actual excitation mechanisms  Piston Piston side forces Piston slap 22 Nonlinear NVH analysis of engines

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

 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  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 simulation results to be close to reality. Furthermore temperature dependencies (oil viscosity and clearances at different operating temperatures...) also have to be considered.  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. Conclusion 24