Simulation Study For Micro-particle Impact On Flat Surface

With the increasing pollution of particulate matter,the phenomenon of particle deposition has been paid more and more attention.When the particle size is reduced to the order of micro-scale,the contact between the particle and the surface is obviously different from that of the macro-size.The van der Waals force and the surface roughness between the contact surfaces play a leading role in the contact process.In this paper,the dynamic characteristics of the collision process between a micro-scale particle and a smooth / rough plate at a lower incident velocity are studied in detail by using the finite element simulation method.Firstly,the static contact model represented by Hertz contact model,JKR contact model and DMT contact model is introduced,and the dynamic contact model obtained by combining static contact model and Newton’s law of motion is analyzed.The results show that van der Waals force plays a dominant role in all the contact forces,and the van der Waals force between particle and plate is analyzed and discussed.Secondly,finite element software ABAQUS is used to study the collision process between particles and smooth plate during elastic deformation.The van der Waals force between particles and smooth surface is replaced by nonlinear spring element,and the action of van der Waals force is considered in the contact process.The variation of particle kinetic energy,strain energy,recovery coefficient,contact displacement and contact time with particle size and incident velocity in the process of particle-surface collision is studied.The results show that the recovery coefficient of particles increases with the increase of incident velocity,and the contact time between particles and smooth plate decreases with the increase of incident velocity.When the incident velocity of particles is 0.5~3.0m/s,the recovery coefficient and contact time change quickly with the incident velocity.When the incident velocity is greater than 3.0m/s,the influence of incident velocity on the recovery coefficient and contact time is small.The contact displacement increases with the increase of incident velocity.When the particle size increased from 2 μm to 10 μm,the recovery coefficient,contact time and contact displacement showed an increasing trend,but for 2μm and 4μm particles,the change trend was not obvious.With the increase of elastic modulus from 75 Gpa to 120 Gpa,the recovery coefficient of particles increases and the contact time between particles and plate decreases.Finally,the collision process between silica particles and rough plate under van der Waals force is simulated.The fractal theory is introduced and the surfaces with roughness of 19.23 nm and 33.66 nm and 44.98 nm are constructed by using the W-M function in the fractal theory.The effects of surface roughness,incident velocity,particle size and elastic modulus on collision characteristics were studied in detail.The results show that when the particle diameter is the same as the incident velocity,when the surface roughness is 19.23 nm,the recovery coefficient of the particle reaches the maximum,the incident time and contact time are the shortest,and the surface roughness increases to 44.98 nm with the increase of the surface roughness.The recovery coefficient of the particles decreases to the minimum values under three roughness conditions,and the incident time and contact time reach the maximum.When the incident velocity is 0.5 and 1.0m/s,the surface roughness has little effect on the incident time.With the increase of incident velocity,the influence of surface roughness weakens.Under the same surface roughness,the impact of incident velocity and particle size on the collision process is similar to that of the smooth plate.Although the increase of elastic modulus of particles has little effect on the kinetic energy of particle rebound,the contact time can be significantly reduced.