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To explore an accurate load spectrum editing method and discover the influence of different types of bench load spectrum on steering knuckle fatigue damage, the verified test field load spectrum was used as the data source and the knuckle endurance specification was simplified. The multi-body dynamics model of the vehicle was verified by the Kinematics Compliance（KC） test of the suspension and virtual iteration method. The bench random spectrum with the features of time and frequency domain was created by the domain editing method. Four-stage bench program spectrum was generated by damge equivalence principle. According to the result of the statistical knuckle’s pseudo damage in all directions and the modal test, the knuckle multi-axis virtual bench was built. The modal stress recovery method is used to compare the fatigue damage under the steering knuckle of the original spectrum, the bench random spectrum, and the bench program spectrum. The result shows that the damage distribution under the three excitations is consistent. The maximum damage ratios of the bench random spectrum and bench program spectrum to the original spectrum were 0.75 and 1.7, the accuracy of the load spectrum editing method and the engineering practicability of the virtual bench are verified. Finally, the load type of the steering knuckle fatigue damage and the road type were determined through the virtual bench transfer matrix, which provides data support for structural improvement.

To explore the influence of virtual road surface method,virtual iteration method and fixed body method on the damage of lower control arm,the data from the test site was used. The accuracy of vehicle multi-body dynamics model was verified by suspension K＆C test and vehicle controllability and stability test. The six-component force signal of wheel center simulation value was compared with test value in the time domain and the frequency domain. The analysis results show the accuracy of 3 D virtual road and tire model; Comparison of simulation value of three methods and test value of the vertical acceleration of the wheel center shows virtual iteration method has the highest precision,and fixed body method has the worst precision. From the perspective of fatigue simulation,the results show that virtual iteration method and virtual road surface method have the same damage distribution to lower control arm. Fixed body method is quite different from the two,and is more conservative. The simulation results of lower control arm under the three load methods meet the durability of the test field.,which was consistent with the test results of indoor bench.

The load spectrum of automotive chassis components is the key factor to analyze the fatigue,reliability and durability of components.However,it still needs further practice and direct verification in the process of extracting road load spectrum and the key link processing,as well as error evaluation,etc.Based on this,this paper takes a certain type of automobile steering knuckle as the research object,established rigid-flexible coupling multi-body dynamic simulation model of the whole vehicle,and calibrated it through the test site reinforced the road test,the error between the monitoring signal of the measured key points and the iterative simulation is less than 30%,which verifies the response accuracy of the vehicle multi-body model; The load spectrum of road surface strengthened by endurance test of real vehicle was collected,and the load spectrum of steering knuckle connection points was obtained by simulation decomposition using virtual iteration method; Take typical working conditions of stone road Cand washboard road as examples,the inertia release method was used to solve the time-domain strain field of steering knuckle by using the load spectrum of connection points as input excitation,and time-domain strain curves of monitoring points are obtained,the relative error of the analysis of measured signals is less than 20%,which meets the accuracy requirements of the subsequent use of the load spectrum.The results show that strain calibration method is a direct verification of the effect of virtual iteration load spectrum extraction,which proves the feasibility and accuracy of the load spectrum extraction technical route,and provides a reference for the development of automobile chassis parts and fatigue durability analysis and verification.

The recession of elastic modulus happening in the plastic deformation of sheet metals had a big influence on the springback prediction in sheet metal forming processes. To study the recession law of elastic modulus for 7075 aluminum alloy sheets, the conventional cyclic loading experiments were used and a new bending-unloading experiment with the assistance of DIC strain measuring system was designed to test the elastic modulus. The testing results show that the elastic modulus has a significant decline with the growth of plastic deformations and the recession law of elastic modulus is influenced by the stress states during deformation. The recession laws obtained by two experiments were applied to the springback simulation of forming processes for a beam with shape C. The comparison between the results of simulations and experiments shows that the analysis results of springback from the recession law of cyclic loading experiments are better than that from the bending-unloading experiments. The prediction accuracy of the four springback angles is increased by 42%, 7%, 40% and 200% separately. [ABSTRACT FROM AUTHOR]