平头压头下基体对压痕规律的影响研究

Study of the Influence of the substrate on penetration depth by the flat cylindrical indenter

本文通过对软薄膜/硬基体两相材料体系的平头压痕弹塑性模拟.重点研究了平压头压入过程中,不同屈服强度比(软薄膜屈服强度与硬基体屈服强度之比)以及不同压头尺寸下硬基体对压痕规律的影响.研究发现硬基体对压痕规律的影响与屈服强度比近似满足线性关系,且这种线性关系不随压头尺寸的改变而改变,相同压头半径下,屈服强度比越大,影响就越明显;相同屈服强度比下,压头半径越大,影响就越小.研究还发现压头压入过程中,材料的堆积对压入深度没有影响.

The indentation process of a soft thin film on a harder substrate by the flat cylindrical indenter has been simulated by means of the finite element method （FEM）. The emphasis was put on the critical indentation depth with the influence of the yield strength ratio of the soft film to the harder substrate and the size of the indenter. The results show that the influence of the hard substrate on the indentation depth can be negligible at a small indentation depth, but this influence can not be negligible after the indentation depth arrives at a critical value. Further studies show that there exists an approximate linear relationship between the yield strength ratio of the soft film to the harder substrate and the critical indentation depth, and the linear relationship is not varied with the size of the indenter. And the critical indentation depth increases with the yield strength ratio of the soft film to the harder substrate when the other conditions are same. Analyses also reveal that on relationship between the critical indentation depth and the enhanced material pile -up around the flat cylindrical indenter.