Research On Material Point-finite Element Coupling Method For Numerical Simulation Of Wound Ballistics

Wound ballistics cares about the various damage of tissues and organs caused by the bullets and fragments hitting on the people,including their movement laws and the Injury mechanism inside the human body.Relevant research is of great military significance.Since the process of bullets/fragments penetrating into the human body involves many complex phenomena such as large deformation,high strain rate effect,dynamic damage and failure,numerical simulation methods have become important tool in the research of wound ballistics.The traditional finite element method and the standard material point method have their own advantages and disadvantages.This paper aims to couple these two methods to better deal with those complex problems in wound ballistics.A material point aggregation algorithm was proposed for the extreme compression situation of materials.In order to avoid the numerical instability of the standard material point method(MPM),the generalized interpolation material point method(GIMP)is used to couple with the finite element method.Besides,the adaptive finite element material point method(AFEMP)is used to deal with the problems of the materials only large deformed partially.These algorithms mentioned above are combined together to form a simulation program,named the 2D-FEM & MPM program.The correctness of each algorithm module of the program is verified by multiple examples.Use the self-developed 2D-FEM&MPM program to carry out the specific simulations of the wound ballistics.In the process of calculation,the AFEMP method was used to describe the gelatin,and the penalty function method was used to calculate the contact force.In order to better describe the high-speed penetration process,an integrated conversion criterion for the gelatin finite element was proposed.The effect of the grid size setting on the calculation results was studied.The numerical results agree well with the experimental results,indicating the correctness and practicability of the coupling method program.Finally,the damage effects of fragmentation and bullet penetration into the gelatin are explored and analyzed.