Sealing Performance Analysis And Structural Optimum Design Of Composite Integral Fuel Tank

The integral fuel tank utilizes the original load-bearing components of the wing or fuselage as the tank wall and bulkhead.Due to its unique advantages,it’s becoming a widely used technology in modern aircraft.Composite materials,represent lightweight and light-strength materials,on the one hand composite materials meet the modern aircraft on the weight loss requirements.On the other hand,its unique characteristics can also meet the strict requirements of the sealing performance of the tank.In this thesis,sealing performance of the integral fuel tank was analyzed under the impact load.Structural optimization and design of composites under the constraint of sealing performance of opening cover structure were carried out,which have important theoretical significance and engineering application value.In this thesis,the fluid-structure coupling model was built based on the continuous and incompressible theory of free liquid.By using DYTRAN to simulate the movement of the fluid inside during the ejection of the drone,the pressure-time history can be obtained.And the impact load under different filling volume was compared and analyzed.A method of automatic creation of Gap elements and Beam elements by NASTRAN input file which modified by MATLAB program was proposed,and the feasibility of this method is verified by a simple model.Then,sealing performance of the fuel tank was examined under the impact load by the fluid-structure coupling analysis.The relationship between the relative deformation and the position of cover under dangerous conditions was studied.In addition,the influence of the change of screw spacing on the maximum relative deformation of the cover was also studied in this thesis.Based on iSIGHT platform and multi-island genetic algorithm,the optimization design method was discussed,where screw connection parameters and structure parameters was considered.The number of screws was seen as the variable and sealing requirement was seen as the constraints,and the optimization design was conducted for the size and layout of the integral fuel tank.The result shows that the weight of the structure comes to good results.