基于特征贡献率的机械故障分类方法

为了使7075铝合金薄壁件表面喷丸加工应力得到松弛和均化，运用ANSYS建立平台式振动时效有限元模型，通过振动模态和谐响应分析，获得最佳激振频率和试样装夹位置。在此基础上，将薄壁框架件置于平台上进行振动时效处理，以验证仿真分析结果，评价其对试样表面应力作用效果。结果表明：在亚共振频率为112 Hz时，试样在平台零振幅和最大弯曲位置处分别对称布置，时效后表面均形成应力松弛，松弛率分别为29.5%和33.3%，不均匀波动分别为20.3%和20.7%，而沿振动方向松弛程度不均匀，说明激振力造成了材料表面组织屈服，且屈服程度与应力强度有关。提出再时效-位置交叠方法，使应力松弛不均匀度分别下降到9.9%和15.9%，应力均化得到改善，该研究工作为薄壁类零件表面应力均匀化提供了参考。

Machinery Fault Classification Method Based on Feature Contribution Rate

The work aims to relax and equalize the shot peening surface processing stress of 7075 aluminum alloy thin-walled components, the finite element model of platform vibration stress relief (VSR) was established by ANSYS.Through modal analysis and harmonic response analysis, the best excitation frequency and sample clamping position are obtained.On this basis, the thin-walled componentsare placed on the platform for VSR treatment to verify the simulation results and evaluate the effect of surface stress on the specimens.The results show that when the sub-resonance frequency is 112Hz, the specimens are symmetrically arranged at the zero amplitude and the maximum bending position of the platform. After VSR, the stress relaxation occurs on the surface of the specimens. The relaxation rates are 29.5% and 33.3%, respectively. Furthermore, the non-uniform fluctuations are 20.3% and 20.7%, respectively.However, the degree of relaxation is not uniformalong the direction of vibration, which indicates that the exciting force causes the micro-yield of material microstructure, and the degree of yield is related to the stress intensity.In this paper, the re-aging and position overlap method is proposed to reduce the stress relaxation inhomogeneity to 9.9% and 15.9%, respectively, improving the stress homogenization. The research work provided a reference for the surface stress homogenization of thin-walled components.