The Experiment And Model Of Film Fracture In The Film-substrate System

The phenomenon of film fracture in film-substrate systems are very extensive.For example:cracking of the field,cracking roads,tree trunk cracks,fracture patterns of industrial coatings.There are a lot of similar situations in life,which bring up many problems,such as what causes the cracks,patterns of the cracks,how to avoid the initiation of the cracks,and how to repair the cracks after they appear.So it is very important to study the film fracture in film-substrate systems.In recent years,we can see that most studies focus on the film-substrate thermal mismatch problem,the buckling problem,and the influence of the thickness ratio of the film from the research of film fracture in film-substrate system at home and abroad.Although the research on the patterns of crack did not have any satisfactory results yet,this topic has much research value.In this paper we take EPDM rubber as the substrate and paint as the film for the experiment to verify the fracture model that we proposed.In the consideration of that we take EPDM as the substrate,in order to observe the crack pattern easily,choose brittle material as the film.In this paper we test six groups of different thickness of specimens and two groups of biaxial tensile experiment.We do tensile tests of film-substrate system with laboratory uniaxial tensile instrument to observe the pattern of the crack.Obtained the experimental data of the six groups of film-substrate system specimens with tensile tests,choose the first order derivative method by observing the characteristic of the scatter diagram,then get the fracture stress of the film by averaging the six groups of fracture stresses. By comparing the fracture model and the experimental data to prove the effectiveness of the fracture model we proposed.