A frequency domain approach for fatigue life （频域方法对疲劳寿命）.pdfVIP

Presented at International Conference on Damage Assessment of Structures (DAMAS 99) Dublin. A frequency domain approach for fatigue life estimation from Finite Element Analysis Andrew Halfpenny nCode International Ltd., Sheffield UK Abstract Fatigue damage is traditionally determined from time signals of loading, usually in the form of stress or strain. This approach is satisfactory for periodic loading but requires very large time records to accurately describe random loading processes. These may prove prohibitive for many finite element analyses especially when modelling dynamic resonance. Alternatively, a compact frequency domain fatigue calculation can be utilised where the random loading and response are categorised using Power spectral density (PSD) functions and the dynamic structure is modelled as a linear transfer function. This paper will review the available methods for performing fatigue analysis from PSDs and shows that the Dirlik method gives the best comparable results with the traditional time domain approaches. It also demonstrates how these techniques can be implemented in the Finite Element environment to rapidly identify critical areas in the structure. the PSD of stress. A review of this method is 1. Introduction presented. It is often easier to obtain a PSD of stress rather To take advantage of the fast frequency domain than a time history. Take, for instance, the dynamic techniques for fatigue analysis, we require a method analysis of complicated finite element models. Here