Fatigue Life Research Of A Three-axis Commercial Vehicle Frame

Frame is an important bearing member of a non-load-car, its fatigue reliability and structural stiffness is directly related to the vehicle life and safety. A lot of research has being done for two-axis vehicle frame, but little for three-axis or multi-axis commercial vehicle frame. Therefore, this paper takes a three-axis commercial vehicle frame as the research object, and does fatigue life analysis of the frame using numerical simulation and advanced test technology. The main contents include:1) Based on the platform of multi-body dynamics software ADAMS/CAR, the vehicle dynamics model is established, dynamic loads of the frame and suspension points are acquired through the vertical displacement incentive, and then the frame fatigue load spectrum of the simulation input is obtained.2) Through theory analysis and software calculation of the three-axis truck chassis structure, eventually determines the boundary constraint condition and calculate the frame in three static condition of torsion bending、bending and twisting, the stress and displacement distribution are acquired, and the key weak parts of the frame structure is determined and its strength has been checked; Through the frame free modal characteristics and modal frequency response computation, analyses the frame of low order natural modal characteristic and frequency response characteristics.3) On the basis of dynamic and static simulation results analysis, the fatigue life calculation of the frame key parts under bad condition (bending and twisting) is done using a combination quasi-static and vibration fatigue life analysis method, comparison of the quasi-static and vibration fatigue life has been completed.This research systematically completed frame fatigue life analysis, established the "modal analysis-frequency response analysis-fatigue life calculation" process which can be applied to other related technology studies of auto parts, and also has certain reference significance the fatigue resistance design of the frame and further optimization.