Optimization Strategies in NVH to Support Lightweight Vehicle Design 2016-01-1776

Lightweight vehicle design causes special demands for functional NVH design. The reduction of weight by reducing material thickness, enabled by new alloys, the combination of materials and new materials increases the sensitivity of a vehicle body to the vibrational and acoustical response of external forces like powertrain or road and wind excitation. To be able to fully raise lightweight potentials design has to be driven closer to functional boundaries, putting higher demands on the accuracy of the prediction by simulation. For a robust design a very broad view on several loadcases is needed to make sure that by optimization on one target no other target is violated. In this paper, optimization strategies for complex NVH load-cases should be investigated in detail. In reality, load-cases, excitations as well as boundary conditions are very often complex and complicated. For complete vehicle view in a frequency range up to 500Hz, beside significant performance gains in the recent years, the simulation time is still something to consider. The paper focus on how to decide between several optimization strategies, developed in recent years to support the vehicle development process at Magna Steyr. General starting point is the hierarchical viewpoint on NVH phenomena to be able to break targets down from complex complete vehicle loadcases to loadcases like dynamic stiffness or noise transfer functions with higher computational efficiency. When needed, complete trimmed body structures are further reduced to optimization regions to enable not only parameter- but also topology-optimization. Beside the general topology and parameter optimization procedures, which are mainly used for structural optimization, this paper shows methods enabling variant design decision and also some new approaches on material efficiency investigation for damping/isolation countermeasures.