Topological Optimization Of Thermal Buckling Reinforcement For Thin-walled Structures

The design requirements of the spacecraft to achieve long range and long flight time make the lightweight level of the structure extremely high,which leads to the thin-walled bearing structure.However,under the requirement of flying speed exceeding Mach 5,violent friction between the surface of the structure and the air generates a lot of heat,and the surrounding air is violently compressed to generate high temperature.In this extreme environment,the thin-walled skin of the airborne load-bearing cabin section will face a complex extreme thermal service environment,and the structure is prone to thermal buckling damage under the action of high temperature thermal environment and large gradient temperature field.The existing aircraft design methods lack corresponding structural design methods.The traditional thickening and reinforcement methods have limited efficiency and are not conducive to lightweight design,which seriously restricts the further development of high-performance thin-walled bearing structures.Focusing on the above requirements,this paper develops a design method of thermal buckling and stiffening for thin-walled structures to provide theoretical basis and optimization guidance for the corresponding structural design.The content of this article is as follows:1.In order to realize the thermal buckling and stiffening design of thin-walled structures,based on the topology optimization of the traditional variable density method,this paper aims at maximizing the critical buckling eigenvalue under the thermal load of the structure,and simultaneously introduces the geometrical constraints of the rib features,combined with nonlinear The density filtering technology proposes a topology optimization method for buckling and stiffening of thin-walled structures under thermal load,and realizes the layout design of buckling and stiffening of thin-walled structures under thermal load.2.The distribution of thin-wall structure skin and bars is of great importance to the critical temperature of thermal buckling.Based on the above topological optimization method of reinforcement,this paper explores the design characteristics of thermal buckling bars with constant skin mass,and the results show that the higher the height of reinforcement bars,the higher the critical temperature of thermal buckling and the better the stability.When the mass of the structure is constant,the higher the mass ratio of the bar is,the higher the critical temperature of thermal buckling is.3.In view of the possibility of thermal buckling failure of the thin-wall structure of the aircraft as well as the bearing design requirements,this paper explores the influence of different constraints on the distribution characteristics of the optimal thermal buckling bars under the constraints of flexibility and mechanical load buckling,respectively.The results show that the flexibility constraint conditions have a certain influence on the distribution characteristics of the thermal buckling bars,but the influence is small and the distribution characteristics of the bars are similar.Mechanical load buckling requirements are quite different from the characteristics of thermal buckling bars.The mechanical load improves the overall stiffness through concentrated materials,while the thermal buckling optimization junction materials are more evenly distributed.At the same time,the disconnected bars are conducive to the release of thermal stress.