Reliability Analysis And Optimization Design Of Leaf Spring Of A Light-duty Vehicle Leaf Spring Based On Spectrum Decomposition Technique

When the car is driving on rough road at a high speed, the reliability of leaf spring will be influenced by impact from road, and sometimes it will cause accident. So it has a great significance to analyze and predict the fatigue of leaf spring. The regular evaluation strategy is based on static and dynamic load modified reliability design analysis. But it fails to have a good reflection of the load characteristics on leaf spring assembly under random road, so it can’t be used in this paper.Based on frequency domain method, the load spectrum on leaf spring assembly under random road was solved and compiled, according to the nominal stress method, and combined with the leaf spring material P-S-N curve, the fatigue reliability is analyzed and forecasted.Firstly, non-linear dynamic model of leaf spring was established in ANSYS, which took friction and contact into consideration, and leaf spring stiffness experiment was conducted to help identify and correct the parameter of model. Secondly, multi-body dynamic model of the vehicle which includes leaf spring refined model was built up in ADAMS, and the model was adjusted and modified according to some design criterions such as suspension partial frequency characteristics. Based on modified vehicle model, transmission characteristics from road random input to leaf spring load output dots was studied. Combined with driving cycle road-surface spectrum, load spectrum characteristics on leaf spring can be calculated.Taking this load spectrum as input and combining with material S-N curve, the fatigue life of leaf spring can be got through random vibration analysis. Based on the analysis results, combined with practical experience and criterion, leaf spring is optimized. Meanwhile, through strengthening road experiment, the equivalent relation of fatigue reliability between practical road input and strengthened road input is studied.