A Refined Synchronous Test Technique For Mechanical Properties Of Film/Substrate System

Thin-film/substrate systems have found increasing application in many advancing technologies,such as mechanics,civil engineering and biotechnology.In real life,many things can be seen as thin-film/substrate systems,such as road subgrade and its surface,roof and waterproof layer.The application of thin-film/substrate systems require a firm interfacial adhesive strength between film and substrate.The adhesion strength is not only the key indicator of film/substrate systems' quality evaluation,but also the premise of the film can play the normal use performance(mechanics,chemistry and physics,etc.).Therefore,it is necessary to evaluate the interfacial adhesive strength of film/substrate systems correctly.At present,most of the mechanical properties of the film/substrate systems are separately measured.Although this kind of approach is very simple and feasible,it does not consider the interaction between the properties of the surface and interface,and the possible errors caused by the two independent experiments.Synchronous measurement techniques solve these problems.This paper analyzes the existing synchronous measurement technology,and puts up with an improved method.In this paper,firstly the theory of mechanical properties of thin-film/substrate systems was studied systematically,and the existing problems of synchronous measurement technology were pointed out.An improved technique for simultaneous characterization of mechanical properties of thin-film/substrate systems was presented.Then,the mechanical model based on the synchronous measurement was solved in detail,and the “small rotation angle” hypothesis was abandoned while the initial stress was introduced,and the “circular membrane problem” was solved again by the power series method.Thus,the theory of “circular membrane problem” was improved.Finally,in order to show the influence of abandoning the “small rotation angle” hypothesis and considering the initial stress,the method proposed in this paper was compared with several existing methods.An example was given to verify the correctness of the proposed synchronous representation technique,and the specific operation method was also given.The main innovation of this paper lay in the fact that the residual stress may exist in the surface film of the thin-film/substrate systems,and the “small rotation angle” hypothesis of the circular membrane problem was abandoned in the process of solving the mechanical model.Thus,the accuracy of the measurement results was greatly improved.It can promote the development of synchronous measurement theory in the future.