The Fatigue Life Analysis Of A Commercial Vehicle Frame Based On The Measured Wheel Six-component Force

Durability,as an important performance index of automobile products,is directly related to the safety and reliability of vehicles under all kinds of working conditions.It has great influence on vehicle quality and reputation.With the continuous development of finite element theory,fatigue theory and test equipment,durability analysis of important parts in vehicle design and development stage plays an important role in shortening the process of product development and reducing the cost of research and development.Take a commercial vehicle frame as the research object,summarized the present research of the related structure in fatigue analysis,acquired fatigue load spectrum based on wheel center six-component force signal measured by six-component force sensor and virtual iterative extraction technology,linear fatigue damage theory is applied to analyze the fatigue life of the frame,and the fatigue life results and distribution of the frame are obtained,providing a basis for the optimization design of the frame structure.In order to meet the needs of fatigue analysis,it is necessary to determine the type of the test signal before the actual road test is carried out to confirm the test equipment.Due to the uncertainty of equipment and the road test,the test signals must first be confirmed by spectrum analysis,amplitude spectrum analysis and signal integrity checking.Select the effective data signal to remove the peak value,remove drift,Fourier filter,resampling and so on to get the available data.The finite element model based on the three-dimensional model of the frame is the basis of fatigue analysis.The simplified simulation of the reasonable structure and connection has important influence on reducing the computation time.The accuracy of the finite element model is verified by comparing the analysis results of the model stiffness and mode with the actual test results.After analyzing the merits and demerits of all kinds of ideas to acquire the fatigue load spectrumbased based on the six component extraction,choose the way of vertical displacement drive instead of vertical force to improve the simulation accuracy.In order to get the vertical displacement of the wheel center,iterate it based on the virtual iteration method.Vehicle Multi-body dynamics model is the basis of virtual iteration and load spectrum decomposition.In order to improve the accuracy of the model,a flexible body model of vehicle frame is established,and the nonlinear characteristiccomponents such as bushing and shock absorber in the suspension system are tested and measured,and the key characteristic curve data are obtained.The load spectrum of the frame fatigue analysis is obtained by using the vertical displacement signal obtained by the iteration and the remaining five components of the six-component force.The fatigue load spectrum,the finite element analysis result file and the E-N curve of the frame are used for fatigue life analysis,and the fatigue damage risk points of the frame are obtained,which provides a basis for the optimization design of the frame structure.In order to verify the accuracy of the simulation results,local fatigue life analysis is carried out based on strain signals measured by road test,and the local life results are compared with the corresponding results of the overall analysis.Based on the actual road test and virtual simulation,the fatigue life prediction of the frame is carried out,which ensures the accuracy of the results while shortening the fatigue analysis cycle of the frame.