Research On Superelement-based Optimization Design Method Of Thin-walled Structure With Thermal Effect

A great challenge in the design of high-speed aircraft is how to select materials and how to design structures to withstand aerodynamic thermal loads during high-speed flight.However,in the existing thermal structure design method,the data conversion between the thermal and mechanical analysis model is tedious and the optimization period is long.Therefore,it is urgent to develop a new method,which not only has enough precision,but also does not need complicated calculation model,to improve the efficiency of the initial design phase of thermal structure.It is of great practical significance to explore the rapid design method of aircraft structure under thermal effect.A superelement-based thermo-mechanical analysis method is proposed for thin-walled metal or composite structures under thermal effect in this paper.Firstly,the thermal analysis model of the structure is established,and the temperature field distribution is programmed by MATLAB software.The thin-walled structure is divided into several superelements along its length direction,and the thermo-structural analysis model is established.According to the basic theory of thermoelastic mechanics and finite element,the superelement stiffness matrix based on generalized force and generalized displacement is derived.The system equation of structural solution under thermal load is constructed,and the MATLAB solver is developed.Secondly,the thermal-force analysis of four different thin-walled structures are carried out,and the results are in good agreement with the results of analytical solution and ABAQUS finite element analysis,which verifies the accuracy of the superelement-based thermo-force analysis method.At the same time,the influence of the number of superelements and the taper of the structure on the calculation accuracy is studied.The superelement-based optimum design method suitable for thermal structure is proposed according to the design idea of full stress/full strain.Three thin-walled structures with different materials are optimized by using this method,and the influence of temperature load on the weight of the structure is studied by comparing the optimization results under different load conditions.At the same time,the influence of the reduction of material properties due to temperature loaded on the weight of the structure is also discussed.The superelement-based thermo-force optimization method can effectively reduce the workload and save the modeling time on the premise of certain precision.It has a broad application prospect in the initial design stage of thin-walled thermal structure.