Development of wear-mode transition model based on analysis of contact mechanics of rough surfaces

本课题的主要目的是通过实验验证Burwell-Strang的假设，即“弯曲率的突然增加是由屈服区从粗糙峰水平过渡到表观接触区水平引起的”，为此，我们尝试了以下方法：1.研制了一种利用商用金属显微镜观察粗糙峰附近变形的试验装置。在实验中，我们测量了预先在较软表面一侧制作的网格在硬体楔体与平坦的软表面之间压入和拖曳后的变形。2.采用滑移线场理论计算模型的数值结果与有限元法的数值结果吻合较好。我们改进了我们的模型，利用有限元的结果。计算了正应力和剪应力作用下真实的接触点的分布。3.研制了一种全反射接触显微镜，用于预测粗糙表面与光滑表面接触时的过渡压力。在这种装置中，我们可以滑动接触面积除了正常的负载。初步研究，我们观察到增长和增加的真实的接触点爆炸完成随机粗糙表面在正常的负载。实验结果表明，该装置能够准确地估算出过渡压力，验证了理论分析的正确性。我们还将尝试发展我们的理论，可以预测磨损过渡压力在广泛的条件下。

The Objective of this project is the experimental verification of Burwell-Strang's hypothesis, that is "abrupt increase of ware rate is caused by transition of yield area from asperity summit level to apparent contact area level".To achieve the objective, we tried these approaches :1.We developed a test apparatus for observation of deformation near an asperity using commercial metal microscope. In this test, we measured deformation of mesh previously made on side of softer surface after indentation and dragging between wedge of hard body and flat soft surface.2.We got good agreement between numerical results of our model used by slip line field theory and those of finite element method. We refined our model using results of FEM. We also calculated distribution of real contact spots under normal and shear stress.3.We also developed a contact microscope using total reflection method, in order to predict the transition pressure of contact between rough surface and smooth surface. In this apparatus, we can slide contact area in addition to normal load. For preliminary study, we observed growth and increase of real contact spots on blast finished random rough surface under normal load. The results indicated that apparatus could estimate transition pressure and verify our theory.We are going to study the effect of normal and shear stress on change of real contact spot. We will also try to develop our theory that can predict wear transition pressure under extensive condition.