Finite Element Study On The Effect Of Wave-shaped Interface On Tensile Fracture Of Film-substrate Systems

The performance and reliability of the film-substrate system structure largely depends on the bond strength and fracture resistance of the film,the modeling techniques for film strength and fracture provide an important basis for the analysis of the film-substrate system.In this thesis,the fracture mechanics and extended finite element method are used as the theoretical basis to study the initiation and expansion of the film surface crack under the uniaxial tension of the film-substrate system and the ABAQUS numerical simulation of the calculation model is carried out and analyzed.The results of the analysis are useful for improving the quality and reliability of many electronic and mechanical technologies.This thesis presents and analyzes the following aspects:(1)makes a brief overview of the concept of a film-substrate system,and sums up the domestic and foreign research on the film-substrate fracture problem and the history of computer simulation of cracks.(2)summarizes the basic fracture criterion of mechanics,the history of fracture mechanics and the theoretical analysis of film matrix cracking.At the same time,introduces the basic theoretical knowledge of ABAQUS and extended finite element.(3)it is proposed to initially consider the influence of the interface type of the flat interface and the wave interface on the structural strength and tensile properties of the film-substrate system when there is spalling in the absence of bonding;then processes the interface connection,which means the binding of any node is relaxed first,and the structural strength and tensile properties of the entire film-substrate system are observed as compared with the flat interface;then relax the multi-nodes arbitrarily and observe the crack propagation of the film-based system;then relax the binding of a row of nodes to observe the crack initiation and expansion of the film surface;finally,randomly arrange a few rows of relaxed binding or evenly spaced relaxation binding to observe changes in the film-substrate system.(4)uses the ABAQUS to establish the film-substrate system and simulates the film fracture under the uniaxial tension of the flat interface and the wavy interface,outputs the simulated data,and uses Origin software to draw the correlation curve and analyze the similarities and differences between the flat interface and the wave interface in crack initiation,expansion and penetration,finally,summarizes the tensile strength of the wave interface and its value for practical engineering applications.The following conclusions were drawn from the analysis: by comparing the load-displacement curve and the stress-strain curve,it can be seen that the wave-type interface film-substrate system has better tensile properties than the flat interface;the stress of the wave-type interface at the trough is greater than the stress at the peak,and the crack is mostly generated at the wave-like trough position;the joint interface is loosely bound and stretched,and the initial crack is found on the unit where the node is loosely bound;the value of the control tolerance can control the number of cracks generated,when the allowable error value is large,the number of cracks increases accordingly,and the allowable error value is small,and the number of cracks is also reduced.