中文摘要：

研究在PI基体上的铜金属薄膜表面Ⅰ型裂纹对薄膜力学性能的影响．以断裂力学基本理论和有限单元法进行数值计算相结合对计算模型分析研究．分析了表面微裂纹对PI基体上的铜薄膜的屈服和后继塑性行为的影响，特别是研究了裂纹深度对最大塑性应变和等效塑性应力的影响，同时考察了薄膜材料硬化指数和载荷对最大塑性应变的影响．随着裂纹深度的增加，裂纹尖端塑性区增大；但当裂纹深度接近和超过薄膜厚的一半时，最大应力值变小，塑性区变大，塑性应变增大．这是因为薄膜承载能力变小，主要是由基体承受载荷．

英文摘要：

The effect of type Ⅰ surface crack of Cu metal film deposited on a polyimide substrate on mechanical properties of the film is investigated. Numerical calculation based on basic theory of fracture mechanics and finite element method is employed to analyze the computational model. The effect of surface microcrack of a Cu metal film on yield and post yield plasticity of the film is analysed, especially the influence of cracking depth on maximum plastic strain and equivalent stress is studied. Meanwhile, the effect of hardening index of the film material and the applied force on the maximum plastic strain is examined. Under the same applied load, both the size of plastic zone around crack tip and the total plastic strain increase as the cracking depth increases, while the maximum stress initially increases and then decreases when the crack depth grows over half of the film thickness. That was attribu- ted to the decrease in load-bearing capability of the film with increasing crack depth, and then the applied load was mainly supported by the substrate.