目的 通过建立双粗糙表面磨削模型,获得微凸体曲率半径对材料磨损的影响大小.方法 选取磨具上微凸体与工件上不同变化曲率的微凸体分别建立滑动磨削模型I和模型II,考虑了磨削过程中材料的弹性/塑性变形及其断裂失效,运用有限元方法分析探讨滑动过程相嵌微凸体的应变变化以及磨屑脱离情况.结果 磨削滑动过程中,在同等接触干涉量δ=1.30μm条件下,接触角较小的微凸体接触对(θ1≈19.4°)其上微凸体发生磨损断裂,而接触角较大的微凸体接触对(θ2≈25.5°)其下微凸体发生磨损断裂.磨损微凸体最大的等效塑性应变量发生在次表层的1.5~2.0μm处.结论 双粗糙表面磨削过程中,在其他影响因素相同的情况下,曲率半径较小的微凸体更易形成磨屑.磨损微凸体最大的等效塑性应变量发生在次表层的某一深度处,随着塑性变形的增大,应力三轴度减小,导致材料表层下微观裂纹的萌生形成磨屑.
The work aims to study the influence of curvature radius of the asperity on the material wear by creating a mi-cro-grinding model. Different variable curvatures of asperities were selected from asperities of abrasive tools and workpieces to create sliding grinding model I and II. By taking elastic/plastic deformation of materials and their fracture failure during the process of grinding into account, stress variation of embedded asperity and abrasive dust shedding during sliding were analyzed by using the finite element method. With the sliding grinding process, upper asperity on asperity contact pairs with smaller con-tact angleθ1≈19.4° was subject to wear fracture while the lower asperity on asperity contact pairs with larger contact angleθ2≈25.5° was subject to wear fracture. The maximum equivalent plastic strain of the wear asperity occured 1.5~2.0μm beneath the subsurface. Abrasive dust is more likely to be present in smaller curvature radius of asperity provided that other influencing factors are the same during grinding of double-faced rough surface. The maximum equivalent plastic strain of the wear asperity occurs in certain depth of the subsurface. Stress triaxiality decreases with the increase of plastic deformation, leading to initia-tion of a micro crack and formation of abrasive dust.
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