Numerical Simulation For Surface Morphology Of Prismatic Projectile Impacting Target Based On Material Point Method

Study of projectile impacting or eroding target surface has far-reaching influence on the development of industry.Reliably forecasting the effect of projectile impacting and the forming of complex surface morphology are always the most important issues.The projectile impacting target with large deformation of accumulation,crushing and separation is a very complex process in which it is difficult to control the parameters,which brings great challenge to the numerical simulation.The material point method uses particle and background grid.The boundary constraint is imposed to the background grid.That the deformed grid is discarded and the new background grid is adopted after each step,effectively avoids the mesh distortion in the finite element method and the border difficulty in the meshless method.It is suitable for the problems of large deformation such as projectile impacting or eroding target.Based on material point method,this article carrys out the numerical simulation research for surface morphology of prismatic projectile impacting target to explore the effect of projectile fliping and the change rule about the surface morphology of target when the projectile impacts target with different initial incidence.Based on the material point method,the program of projectile impacting target is writed and verified.Firstly,the weighted residual method is used to elicit the control equation of material point method,establish the calculating formulation of projectile eroding target,and give the explicit calculating process of the material point method.Secondly,the programs of projectile impacting target is writed by using the fortran language based on the material point method.Finally,the self-programming is used to simulate the process of prismatic projectile vertically impacting metal target in order to analyse the phenomenon of projectile rotating,the crater profile of the chip piling-up heights and the crater depths.Also,the simulation results based on the material point method is compared with that based on the SPH-FEM method and experimental results.The results are in good agreement,which verifies the validity of program.The numerical simulation research for surface morphology of prismatic projectile impacting target is carried out based on the material point method in order to explore the influence of projectile impacting with different rake angle,impacting angle,impacting velocity on the projectile rotating and the surface morphology of target,to analysis and compose the change rule of the chip piling-up heights and the crater depths.The results show that the projectile rotates backward to form a crater profile by clockwise torque when rake angle is smaller in the case of different rake angle.The projectile cuts target,which leads to the separation of chips from target and the forming of the shallow and smooth crater.The roughness is smaller.On the other hand,the projectile rotates forward to form a crater profile by anticlockwise torque when rake angle becomes larger.The projectile rolls target,which leads to the chips piling up at the edge of the crater and the forming of the angular crater.The roughness is bigger.The larger the impacting velocity is,the more obvious the effect of the chips piling up is when the projectile which impacts vertically does not rotate,and the more chips are.The orthogonal experiment is carried out by using numerical simulation.Range analysis shows that the combination of 33° rake angle,60° impacting angle and 150m/s impacting speed affects mostly the depth of crater.Variance analysis show that the relationship to the significance level of three factors is:rake angle>impacting speed>impacting angle.In this paper,a new research method is provided for simulating prismatic projectile impacting the surface of target,and also provides some guidance for the basic research in the industrial application field.