渗氮钢粗糙表面的弹塑性接触研究

利用弹塑性有限元和单纯形法求解弹塑性接触模型，分别模拟了屈服强度呈梯度变化的渗氮钢、未经处理的匀质材料和硬涂层材料粗糙表面的弹塑性接触行为。与未经处理的匀质材料相比，渗氮钢可承受更大接触载荷。在相同载荷作用下，渗氮钢表面粗糙峰接触面积较小，平均间距较大，接触体内材料不易发生屈服，从而显著提高接触性能。和硬涂层材料相比，渗氮钢接触体内等效von Mises应力分布平缓，没有应力突变。最后讨论了渗氮层和硬涂层的厚度对粗糙表面接触特性的影响。

Elastic-Plastic Asperity Contacts of Nitrided Steel

Using the finite element method,an elastic-plastic asperity contact model was developed to analyze the contact performance characteristics of nitrided steel,hard coating material,and homogenous material.Plastic yielding and strain-hardening properties of the materials were taken into account.The von Mises yield criterion was used to determine the inception of plastic deformation.Effects of gradient yield strength on contact pressure,real area of contact,average gap of rough surface,and von Mises stress distribution under elastic-plastic contact conditions were investigated and discussed numerically.Results indicate that nitride steel alters the distributions of contact stress,contact pressure,real contact area,and the gap between rough surfaces,compared with homogeneous materials in contact.Furthermore,when the hard nitrided layer is sufficient thick,contact characteristics become independent of the path of the yield strength variation,and are dominated by the yield strength of nitrided layer.