Stability Analysis And Optimization Design Of Special-shaped Fuel Tank

Due to structural characteristics,the special-shaped tank has good designability and adaptability,which can meet all kinds of design requirements of spacecraft.However,due to its complex structural forms,the special-shaped tank has the characteristics of large design space and non-uniform load distribution.It causes that the design and optimization of specialshaped tanks are more challenging than traditional tanks.Due to low imperfection sensitivity and high specific stiffness and strength,stiffened shells are widely used in the aerospace field.As the main load-carrying component,the load-carrying capacity of stiffened shells which can greatly improve the efficiency of the structure,has not been fully developed.In order to meet the lightweight design requirements of special-shaped tanks,it is very necessary to develop reinforcement layout optimization design for special-shaped tanks.In this thesis,an integrated multilayer reinforcement optimization framework is set up for the special-shaped tank and the reasonable reinforcement design is obtained.Results show that the optimum design improves the efficiency of the structure and plays a reference role in the engineering design.The main works of this thesis are as follows:1.For stability problem of special-shaped tank,based on the explicit dynamic analysis method,the influence of the height and internal diameter of the tank under axial pressure and internal pressure on the load-carrying capacity is discussed.Results show the special-shaped tanks have the characteristics of competing instability modes under combined internal pressure and axial compression,and the synchronous instability of inner and outer skin is the most competitive mode of instability.2.Aiming at the optimization design of the special-shaped tank,an integrated multilayer reinforcement optimization framework is set up.Based on the optimization frame,the reinforcement layout optimization design is carried out,and the optimum configuration is compared with the initial configuration and the thickness optimization configuration.Compared with the traditional design configuration,the optimum configuration has a weight loss of 7.1% under the condition that the ultimate capacity is unchanged.Compared with the initial design configuration,the collapse load is increased by 5.2% while the structural weight is reduced by 7.1%.Results show that the validity of the optimized design framework is confirmed,which can be used as a reference for practical engineering design.3.Considering the initial geometric imperfection,the imperfection sensitivity analysis of the stiffened special-shaped tank is analyzed.The effects of the single dimple-shape imperfection on the load-carrying capacity of the stiffened special-shaped tank are studied.Results show that the special-shaped tank is insensitive to the single dimple-shape imperfection of the inner and outer skin,and the layout optimization design of the special-shaped tank effectively restrain out-of-plane deformation.Considering the single dimple-shape imperfection of the outer skin,the special-shaped tank is more insensitive to the single dimpleshape imperfection of the inner skin.