Optimization And Protection Mechanism On Structure Of Stab Resistance Body Armor Based 3D Printing

In recent years,the violent accidents of knife stabbing frequently happened that deeply threaten people life.Thus,the research of stab-resistance body armor(SRBA)has become a hot topic on the public.However,there are many disadvantages of traditional SRBA,such as heavy weight,poor thermal comfort,which causes heavy heat stress for people wearing it.Based on that,it is of great importance to research and develop lighter and more comfortable SRBA.Inspired by bionics structure,scientists and engineers have started to design innovative SRBA,which could be achieved by using 3D printing technology.In this paper,pyramid structured SRBA was designed and produced by using laser sinter technology.The stab resistant performance was studied by the numerical simulation and experimental verification,meanwhile,and the optimization was confirmed.The best design of laser sintered pyramid structured plate by polyamide 3200(PA3200)is that pyramid angle of 22.5°and plate thickness of 6.75 mm.When comes to polyamide/multi-walled nanotubes(PA/MWNT),the pyramid angle is 25°and plate thickness is 6.25 mm.Furthermore,connection of the whole protective layer was designed with the mode of rivet type and hinge type,and they pass the test of knife impacts.The main researches of this paper are as follows.(1)The stab resistant mechanism of squared nylon plate and pyramid structured plate was studied by using numerical simulation.The results show that the stab resistant performance of pyramid plate is much higher than squared plate.It can be explained that the pyramid structure diverts the impact force,which prevents the concentrated destruction of the impact kinetic energy.Meanwhile,the stab resistant performance of pyramid structured plate is firstly increasing and then decreasing with the angle of pyramid increasing.Stab force of knife and the impact system's energy conversion were analyzed to prove this conclusion.(2)Knife impacting experiments were conducted that consider different materials,structures,plate total size,pyramid size and so on.The results show that,the stab resistant performance of polyamide/multi-walled nanotubes and polyamide/glass fiber is higher than polyamide 3200;the stab resistant performance of single layer plate is higher than double and multiple layer plate;the stab resistant performance of pyramid structured plate is higher than squared plate.In addition,the stab resistant performance of pyramid structured plate is firstly increasing and then decreasing with the angle of pyramid increasing,firstly increases and then keep stable with plate thickness increasing,firstly increases and then decreases with pyramid size increasing,decreases with plate total size increasing.(3)The protective layer of SRBA was designed.The first method is about a rivet connection,the protective layer was laser sintered with a short time and shows high flexibility and permeability.The second method is a hinge type,the stab resistant performance of the protective layer is excellent and exhibit both lightweight and flexibility.Both of them meet the test requirements and have widely appreciable prospect.