Abstract: A compiled method of programed load spectrum is presented, which can simplify and accelerate the body fatigue bench test. Random load spectrum of the interface points between chassis and body, which is obtained accurately by road load spectrum collected on the proving ground, is simplified to torsion load spectrum. Based on rain-flow counting method and statistical theory, the distributions of amplitude and mean are found to confirm with normal distribution and Weibull distribution respectively. Following that, the programed load spectrum is compiled and simplified. The fatigue life of the body is predicted using finite element method(FEM) and fatigue analysis theory, and the critical regions are analyzed in terms of fatigue time and driving distance. Through comparative study of the simulation result of random load spectrum and programed load spectrum, the damage distribution and fatigue life are found to agree well with each other, which demonstrate the effectiveness of the presented method. The compiled method of programed load spectrum can help other vehicles to improve the performance.

Key words: body;fatigue;load spectrum;bench test;accelerated test