New Approach for Vehicle System NVH Analysis - Part I: Concept and Vibration Analysis

The concept of a new finite element analysis methodology to solve vehicle system NVH problems is proposed. The approach is non-conventional in the sense that, instead of NASTRAN type implicit finite element code, the explicit nonlinear dynamic code LS-DYNA is used to conduct the time domain analysis and the FFT is then used to conduct the frequency domain analysis. The advantages of this new approach include the ability to consider material and structural nonlinearity, damping and contact interface between parts, as well as the potential of expand the frequency envelop up above 200 Hz. The main disadvantage of this method is the computing CPU time required which will become less and less important as computer speed becomes faster and faster at an increased pace. Examples of normal modes for rectangular plate, tire/wheel system, and chassis subframe are presented to illustrate the method and comparisons with results from other methods are also given whenever possible.