Automotive Structural Durability Design Using Dynamic Simulation and Fatigue Damage Sensitivity Techniques 2010-01-0001

It is well known that product durability is related to three major factors, the structure, load and material. That is, the durability performance of an automotive product is not only depended on the structure configuration, but also related to the load dynamic characteristics (such as, profiles and frequency spectrum), and the material fatigue properties as well. Due to the fact that the automotive vehicle loads are dynamic in nature, one of the major technical challenges to the product durability design is how to quantify the fatigue damage sensitivity.

This paper presents a procedure of automotive structural design for durability performance based on the structural dynamic simulation and fatigue damage sensitivity techniques. A methodology for calculating the fatigue damage sensitivity is introduced. Dynamic stresses of an automotive structural system under multiple simultaneously applied proving ground road loads are first simulated, using the finite element model and dynamic simulation, in time domain response analysis. The high stress of each component is then sorted out and converted into the corresponding power spectral density (PSD) result in the frequency domain by using the fast Fourier transformation technology. The fatigue damage and its damage sensitivity of each component are in turn computed as functions of the dynamic stress PSD properties and material fatigue parameters, with respect to the design variables selected. In this way, the design variables that impact the durability life the most can be identified, as to achieve an optimal durability design with the given conditions.