多层交替膜界限载荷研究

Analysis of Multi-layers under Circumscription Loading

为了研究软硬交替多层表面膜在磨粒作用下的应力应变响应、膜层界面剥离和裂纹的产生及扩展的影响,采用大变形接触弹塑性有限元法对刚性基体上的TiN/Ti多层交替膜在法向压痕作用下的力学行为进行了模拟和分析,研究不同软硬膜层厚度比下,不同膜层的变形、界面切应力分布和表面张应力分布,分析得出界限载荷变化规律及参数分布对其影响情况。结果表明:当软层厚度小于或等于硬层厚度时,增加膜层总厚度可以明显增大多层膜层体系的界限载荷,而软层厚度大于硬层厚度时,增加膜层总厚度不但不能明显增加界限载荷,反而会因增大最大弯曲应力而使界限载荷变小;软硬层厚度比大,而膜层总厚度小的多层膜体系,具有相对较小的最大弯曲应力,因而能承受最大的界限载荷。

In order to analyze the stress-strain responses,the debonding of interface,the crack initiation and the propagation of the layers, which are the alternative hard and soft multilayers under circumscription loading, and explore the methodologies of optimum design of surface multilayers,large strain elasto-plastic finite element method was used to evaluate the mechanics behaviors of TiN/Ti multilayer films on rigid substrate under hard asperity indentation. Based on the analysis of film deformation, interfacial shear stress and surface tensile stress distribution at different total thickness of hard and soft multilayers, the variation of circumscription load with film thickness and ratio of soft-hard layer was obtained. The result shows when the thickness of soft layer is less than the thickness of the hard layer, the circumscription load of multi-layers would obviously increase along with adding the total thickness;when the thickness of soft layer is larger than the thickness of the hard layer, the maximum bending stress was increased and the circumscription load was decreased. The multi-layers with bigger ratio of soft-hard layer and smaller total film thickness has smaller bending stress, so it can endure strong circumscription load.