Finite Element Simulation And Experimental Comparison Of Bulletproof Performance Of Bionic Flexible Laminated Structure

In the field of bulletproof vest,bulletproof vest is generally divided into soft bulletproof vest and hardware bulletproof vest.Although the soft bulletproof vest has strong deformability,it can provide limited protection and is easy to cause blunt injury to the wearer.The hard bulletproof vest can support a higher level of protection,but it is bulky and uncomfortable to wear.In view of this,the biomimetic design of bulletproof vest is carried out with reference to bony fish scale layering,multi-stage structure and covering mode,and a fish-scale flexible laminated structure with both protective performance and flexible deformability is obtained to replicate the excellent performance of natural scale armour.The system analysis of the structure is carried out by means of mathematical modeling,finite element simulation and experimental test,and some useful conclusions are obtained,which are summarized as follows:The composite scale is a double-layer composite structure with thick middle and thin edge.Through the method of mathematical modeling,the relative position relationship of each scale in the plane arrangement is obtained.According to the coordinate formula,combined with the respective advantages of MATLAB and APDL command stream,a parameterized finite element model is established.According to the principle of "efficiency-cost" ratio and the principle of acoustic impedance,several commonly used bulletproof materials are compared and analyzed,and finally Si C ceramic and ultra-high molecular weight polyethylene are selected as the upper and lower layers of the biomimetic composite scale respectively.On the basis of the mathematical model,the formulas for calculating the surface density and the overall thickness of the protective structure are derived.The allowable value of flexibility is introduced to evaluate the bending deformation capacity of this bionic flexible laminated structure,and its quantitative expression is derived.Combined with the calculation formula,the effects of scale arc radius and coverage angle on the weight and bending deformation ability of protective equipment are quantitatively analyzed,which provides a theoretical basis for the optimization of protective structure parameters.The finite element model of the protective structure in the bending state is established,and the influence of the coverage angle on its bulletproof performance is analyzed.Finally,taking the allowable values of area density and flexibility as the objective function,combined with the residual velocity of the bullet and the displacement of the target scale,the optimal values of arc radius and coverage angle are obtained.The bulletproof performance of flexible laminated structure is simulated by using the explicit analysis method of ANSYSLS-DYNA software,mainly from the aspects of structural deformation,stress transfer law,energy dissipation mechanism and bullet residual velocity,with emphasis on the effects of the number of support points,radius of curvature,coverage angle and impact position on the protective performance.The finite element models of single-row and multi-row arrangement of scales with cement backing are established.The simulation results of the depression depth of the back cushion when the scales are arranged in single row and multi-row are 32.52mm and 24.73mm respectively.According to the requirements of NIJ standard class,the live test of flexible laminated structure is carried out,and the results show that the test sample has the disadvantage of local two-point support after multiple bullet penetration.In the case of single row of scales,the error between the simulation results and the test is about 11.6%,which verifies the validity and accuracy of the finite element model.The results of this research will be of great significance to the design and preparation of new flexible protective equipment.