Simulation Of Particles Impact In Explosive-Driven Compaction Process Based On Material Point Method

Explosive compaction is a process of compacting powder materials into dense,good-quality blanks by applying external shock waves.It is a new type of molding process that is considered to have enormous potential for development.Its advantages are that it can effectively reduce or even eliminate the production of intermediate compounds,And also make the material maintain good performance in the very simple molding process.It has been widely used in engine blades,space shuttles and military equipment and other fields.The object of explosion compaction is a pre-compressed powder porous material.The whole process is accompanied by strong transient,strong nonlinear and strong coupling,so there are many deficiencies in numerical simulation using traditional numerical methods such as finite element and Euler methless.Material point method is a new type of meshless particle point method.It avoids the disadvantages of finite element mesh method and Euler meshless method,and combines their advantages.It is a potential for studying large deformation problems.Using the material point method can better solve the dynamic response of the porous body and the large transient deformation problem under the impact load.In this paper,material point method was used to simulate the explosive compaction process.Based on the verification of the material point method simulation of the accuracy of compaction of steel powder particles in the elasto-plastic material model,the influence of various parameters of the explosion compaction on it was further studied..The weighted residual method is used to derive the weak form of the point-of-spot control equation and its discrete form.Analyze and compare the three stress update formats used in the material point method.A material point method for solving the problem of simulated explosion compaction was established.The concrete realization process of the explicit method of material point method is given.The material model and the equation of state used for explosive compaction materials were determined.The material point method for simulating 3D explosion compaction molding problem was programmed in FORTRAN language and the process was numerically simulated.The simulation results were compared with the results obtained from ABAQUS software in the literature.Based on the verification of the accuracy of the compaction of steel powder particles in the elasto-plastic material model by verification of the material point method,the influence of different models and parameters of explosion compaction on the molding process was further studied.Different compaction models were established to study the law of explosive compaction.Through the numerical simulation of the two-ball positive collision,the phenomenon of micro-explosion welding at the two ball contact surfaces was observed.Through the numerical simulation of the three-ball collision,the different compaction speeds under the conditions of the positive and negative triangles were studied respectively.Particles with different friction coefficients,different particle sizes,and different material models influence the pore closure.The method of particle consolidation for the three-ball model was determined by the two cases,and the effect of various parameters on the pore closure was also derived.Finally,a multi-pore and multi-contact seven-particle model was established by analyzing different particle shapes and different compaction speeds.With the influence of different friction coefficients on the explosion compaction,the parameter values suitable for the explosion compaction molding process are obtained.The research in this paper provides new methods and ideas for numerical simulation of explosive compaction forming process,and also provides reference for numerical simulation of other large deformation forming processes.