Optimal Design And Dynamic Characteristic Analysis Of Composite Seat-sheet Structure

The base plate is the main load-bearing component of the mortar.Usually,the base plate occupies a large proportion in the mass of the entire mortar.Therefore,it is of great significance that lightweight materials are applied to reduce the mass of the base plate to improve the mobility and portability of the mortar.Based on a pre-research project,a composite material base plate was designed,and its dynamic characteristic analysis and structural optimization design were carried out.The main research contents of this paper are as follows:Firstly,a composite base plate structure for a large-caliber mortar is proposed.The shape of the seat plate is circular,and the three handles are depressed downward to form trapezoidal protrusion.According to the performance requirements of the base plate,the characteristics of the composite material and the design principles of the layer design,the titanium alloy was selected as the material of the socket,the rest of the structure was made of composite material,and the way of lay-up of composite material was determined.The reinforcing ribs are arranged on the base plate to improve the stiffness and strength of the base plate structure.Secondly,a finite element model of the impact process of carbon fiber composite materials and titanium alloy plate was established,and simulation calculations were performed.According to the constitutive relationship of composite material and material failure and degradation criteria,a VUMAT subroutine for composite materials was written in Fortran software,and the VUMAT subroutine was embedded in finite element software to simulate and analyze the calculation example.The simulation results are in good agreement with the experimental results,which verifies the rationality of the VUMAT subroutine for composite material.The VUMAT subroutine was used to analyze the impact characteristics of composite laminate under different punch kinetic energy,different titanium alloy plate thicknesses,and different laying methods.Thirdly,a finite element model of a mortar coupled with a composite base plate and soil was established.The dynamic stress and dynamic displacement response of the composite base sheet under 6 different firing angle conditions were obtained.The results show that the composite base sheet does not undergo harmful deformation and failure.By changing the finite element model,the influences of the soil type,the height of the socket center and the mass of the base plate on the firing stability of mortar were obtained,which provided a reference for the optimization design of composite base plate.Fourthly,Aiming at the problems of large caliber mortar finite element model with a large number of meshes,many working conditions and long simulation time,a 5-layer BP neural network agent model was established instead of the finite element simulation model,and the optimal Latin hypercube test design was used to train the sample data,a multi-operating condition and multi-objective joint optimization modeling method for the composite base plate is proposed.The target is the mass of the base plate and the muzzle disturbance when the projectile exits the muzzle,and the hard and weak soil are the firing conditions,the maximum stress of the base plate is the constraint condition,and the thickness of each layered area of the composite base plate and the height of the center of the socket are design variables.A multi-operating condition and multi-objective joint optimization model of the base plate is established.The genetic algorithm NSGA-Ⅱ is used for multi-objective optimization.After optimization,the stiffness,strength,firing stability and mass of the composite base plate meet the requirements.The research results of this paper have certain engineering reference value for the design,analysis and optimization design of composite base plate.