Numerical Simulation Of Fracture Dynamics Of Several Quasicrystalline Materials

Due to its remarkable characteristics of high temperature resistance and oxidation resistance,the quasicrystal thermal barrier coating is widely used in engine and other components.The engine thermal barrier coating technology is to spray thermal barrier coating into internal combustion engine internal parts to make the base metal plays the role of thermal insulation and shielding,so as to promote the complete combustion of fuel and reduce the emission of harmful gases and the consumption of cool water.The defects such as cracks,holes,dislocations and inclusions are the main reasons affecting the strength of quasicrystal materials.Therefore,the research of quasicrystal fracture mechanics has become the focus on scientific researchers in mathematics,mechanics,engineering and other related fields.Based on the wave telegraph model of quasicrystals,this paper studies the dynamic response and crack propagation of octagonal symmetric quasicrystals and three-dimensional icosahedral quasicrystals under load impact.The main work arrangements are as follows:The first chapter describes the research background and research status of quasicrystal dynamics,and preliminarily introduces the quasicrystal dynamics model,the finite difference method,the compact finite difference method and other numerical methods.The second chapter,based on the wave telegraph model,a discrete scheme for mixed accuracy is constructed by using the finite difference method to solve the dynamics of octuple symmetric quasicrystals with mode I Griffith cracks,and the error estimation and stability analysis of the discrete scheme is carried out.Through numerical examples,the variation laws of displacement and stress with time are shown,and the effects of effective mass density and friction coefficient on the displacement of phase subfield are explored.For the rapid propagation of quasicrystal crack,with the increase of,the more difficult the crack propagation is,the longer the crack begins to propagate,the lower the crack propagation speed in the initial stage,and the greater the amplitude of the change of stress intensity factor.Based on the wave telegraph model,the third chapter studies the rapid propagation of quasicrystal crack,explores the influence of loading load on crack propagation length and propagation speed,analyzes the characteristics of crack propagation,and puts forward possible solutions.The forth chapter,the wave telegraph model is applied to the dynamics of three-dimensional icosahedral quasicrystal.The influence of load waveform under stress intensity factor is mainly explored,and the compact finite difference method is applied to the solution to phonon field.The local truncation error of phonon field space reaches fourth order.The differences between finite difference method and compact finite difference method are compared.The fifth chapter is the conclusion and prospect,summarizes the innovation and deficiency in this work,and looks forward to the next research work.