Identification Of Elliptical Particle Force Chain And Analysis Of Different Shape Particle System Parameters

In recent years,particulate matter has always been the focus of attention,and is also the focus of research workers.The study of the force and motion of a single particle is relatively simple,which satisfies Newton's law of mechanics and linear momentum balance of particles.However,when a large number of particles form a particle system,the macroscopic mechanical properties of the particles will become very complex,and it is also an important content of the present scientific research scholars.Force chain is a bridge between micro-particle and macro-particle system,and it is an important way to study the mechanical properties of particle system from the angle of force chain.In this paper,the two-dimensional particle system is studied,and the digital image correlation(DIC)method is used to identify and analyze the force chain of elliptical particles under concentrated load.The force chain length,load change and displacement change of different shapes of particles are compared and analyzed.PFC simulation software makes further analysis of the force chain changes of elliptical particles.The specific research contents are as follows:(1)Summarize the research status of domestic and foreign scholars on particulate matter and force chain,put forward the main content of this paper,and briefly introduce the main method used in this paper-digital image correlation method.(2)Loading experiments of particles with different shapes.Elliptical,hexagonal and quadrilateral particles were used to carry out the concentrated loading experiment,and CCD camera was used to record the whole loading process for subsequent calculation and data processing.(3)Through the digital image correlation calculation of the elliptical particle experimental pictures,the variation laws of the displacement,strain and strain contour lines with the loading process are obtained,and through the MATLAB program,Newton mechanics theory and particle linear momentum balance theory are applied to calculate the contact force between particles,so as to realize the force chain of the elliptical particle system.Extraction and analysis.(4)For elliptical,hexagonal and quadrilateral particles,the variation of force chain length with loading process is calculated manually;the variation of load during loading process is deduced from universal testing machine,and the reasons for this change are analyzed;the variation of force chain of elliptical particles is compared with that of circular particles.Through digital image correlation calculation,the displacement field of four kinds of particles is analyzed,and the common law in the process of change is obtained.(5)Using PFC numerical simulation software,the elliptical particles were simulated under concentrated load,and the velocity field,displacement field and force chain were analyzed.