The Study For Force Chain When The Ball Particle System Under The Concentrated Force

In engineering practice, the mechanical properties of particulate materials have avery important significance. The propagation path of force between the particles (ieforce chains), determines the macroscopic and microscopic mechanical properties ofparticulate matter. Due to the discreteness and energy dissipation of particulate matter,the movement of particles is uncertain and disorder, the distribution of the contactforce and force chain between particles determine the mechanical properties ofparticle.In order to obtain the size of contact force and the distribution of force chain inreal ball particles, we used digital image correlation (DIC) method to test thetwo-dimensional balls particles by concentrated stress, and then we got the contactforce using Newtonian mechanics and particle theory of linear momentum balancerequirements in Granular Element Method (GEM) methods. This paper carried out thefollowing works and got relevant outcomes:(1) By reading the related literature in domestic and international which researchon the properties of the particulate matter, it is can be known the current situation offorce chain development. We studied the basic principles of DIC method and itsadvantages in study of the properties of particulate materials. We learned the GEMmethod and its application in particle research of force.(2) The experiment of single layer ball particles by concentrated pressure can bedesigned. Using continuous acquisition of CCD camera, we got the force of ballsduring exercise by the initial image. For post-processing，we used digital imagecorrelation method to get the full strain. The stress can be obtained by the fullaccording to Hooke’s law. Using Matlab program processes initial image to get thestructure and arrangement of particles and the average stress on each particle.(3) We analyzed the principle of using Newtonian mechanics and particle theoryof linear momentum balance requirements in GEM methods to get contact force inparticles and calculated average stress and particle arrangement structure. Finally, we obtained the size and the direction of the contact force between particles and thedistribution force in particles.(4) Based on the statistical analysis of the distribution of strong chain lengthbetween particles, we got the probability density function of the distribution of strongchain length between particles; With the help of Matlab, we draw the distribution ofcontact force arrows between particles and obtained the strong weak force chainappears, the development, the forming process forces and the evolution of the chainnetwork when the rigidity layering pressed into the particle system; through trackingthe change of the contact force on a single particle, we got the contact force betweenparticles could decrease then increase in the process when original strength forcechain break and a new strength force chain form. For other strength force chainincluding chain network has the same rule above.