多层表面膜在滑动接触时的弹塑性有限元分析

Elastic-plastic Deformation Analysis of Multi-layers Surface Coating Under Sliding Contact

本文研究梯度层、三明治层及普通多层膜覆层体受相同表面载荷滑动接触作用下的弹塑性变形情况。结果表明从表层至基体弹性模量逐渐降低的正梯度硬覆层体，能显著改善膜层与基体界面附近的应变分布，沿纵向的应力分布曲线非常平滑，在膜层与基体界面间及基体中的应力较小；三明治覆层能显著降低膜层与基体界面处的最大剪应力，且裂纹尖端的应力值最小，但在界面附近的应力值和应变梯度很大；普通多层膜与单层膜相比，应力、应变分布没有明显的改进。通过对上述四种覆层体在应变、应力分布及裂纹应力场的分析可知，梯度层在这几方面都有较明显的优点，其它三种覆层体虽在某一方面有最突出的优点，但却在其它方面存在最明显的缺点。本文研究结果可为选择及设计覆层膜提供参考。

The sliding contacts of gradient layers,sandwich layers and ordinary multi-layers coatings subjected to the same surface load have been investigated under elastic-plastic deformation in this paper. The result shows that the positive gradient layers coating, in which the elastic modulus reduced gradually from the top layer to the substrate, can improve the strain and stress fields near the layer-substrate boundary greatly and its stress contour in the vertical direction is very smooth. Also its stress is small on the layer-substrate interface and in the substrate. The sandwich layers coating can reduce the maximum shear stress greatly on the interface of the layer-substrate and the stress at the crack tip is minimum, but the stress and the strain gradients near the interfate is very large. The stress and strain distributions of the common multi-layer have not distinctly improved compared to those of single layer. Known from the analysis of the stress and strain distributions and the crack stress fields for the four kinds of coatings, the gradient layers coating has more advantages in these aspects. Each of the three other coatings has its own excellent performance in some respect but also exists its obvious shortages. The results of this paper can offer the reference for the selection and design of coatings.