Lightweight Howitzer Dynamic Characteristic Analysis And Structural Optimization

Under the background of a National Defense Project, a lightweight towed howitzer (LTH) has the problems of poor firing stability and dissatisfied structural stiffness and strength. In this paper, nonlinear finite element theory was used to study the dynamic characteristics of the LTH under its launch load. Then, structural optimization technique was applied to its top carriage for topology optimization, and sizing optimization.This paper from three aspects:the matric representation of elastic-plastic deformation of soil and its solving method; the contact/collision between parts; the numerical method of solving dynamic models, study finite element method for the nonlinear launch process of artillery. Nonlinear dynamic models of the LTH were established. Nonlinear factors, such as, contact/collision between the spade and soil; plastic deformation of soil; mechanical characteristics of elevating and equilibrating mechanism were considered in the models.Through numerical simulation of firing process of the LTH, the responses under its launch load were obtained, and analysis of dynamic characteristics of main components and key parts were carried out. Parts of the simulation result were compared with the experimental values to verify the correctness of the nonlinear dynamics model.The influence law of main structural parameters, such as, location of the trunnion, length of the trail, the buffer device, the elevating and equilibrating mechanism, the spade, on firing stability was obtained through the analysis of nonlinear dynamic models with different structural parameters. Based on this, structural parameters that have a great influence on the firing stability were changed, to improve the firing stability of the LTH.Topology optimization method SIMP was carried out on the top carriage of the LTH to get its optimal topology. According to the optimal topology, the top carriage was rebuilt and sizing optimization was done. With the increase of7.89%in mass, the maximum stress value and trunnion displacement of each load condition achieved remarkable decline, and the optimized top carriage was significantly improved in its structural stiffness and strength.The result of this thesis can provide some reference for the overall layout of the LTH and the design of the top carriage.