The Supercavity Vehicles Shell Structure Stability Reliability Analyse And Optimization

For the columniform shell of the type of supercavity vehicle, the main failure type is the integral structural instability. Therefore, taking the steady motion as the first condition, the reliability analysis of the integral structural stability is accorded with the practicality work. The shell structure should be strengthened in order to keep the integral structural to be stability. And, the strengthened shell is asked for the integral structural stability improved and the weight minimally increased, so that it is necessary to optimize the strengthened shell of the supercavity vehicle, and which is the aim of this paper. The main research works of the paper are as following1) Free-streamline flow over a n-sided polygonal contour is researched by the conformal transformation method, the expression of the force and the moment acting on the contour calculated is achieved. The center position of the instability supercavity is researched, and the expression of the instability supercavity center position is obtained. The force and moment acting on the vehicle is analyzed, and the expression of the force and the moment is obtained on the condition of the plane force and the part cavity. Finally, the expression of the force and the moment acting on the supercavity vehicle is obtained.2) The steadily moving of the supercavity vehicle is simulated, and the analysis of structure is completed. Three-dimentional motion equation of the supercavity vehicle is established. Three representative motion balances of the supercavity vehicle are researched on the condition of steadily moving, and the expression of the balance connection angle at the time of the supercavity vehicle steadily moving is obtained. The model is established according to the test model, the simulation calculate is worked by programming, and the result of the balance connection angle at the time of the supercavity vehicle steadily moving is obtained, finally, the result is analyzed. 3) The structure is analyzed by the new constraints method, thus, the result of the structure analysis is accorded with the face much more. The kinetic and strain energy of the shell is obtained by used thin shells theory. The Mass, stiffness and geometric matrices is given through the use of the nodal displacement vector, and the equation of motion for the shell can be rewritten. The time-variations for the axial force which acting on the shell is considered, the motion equation for the shell used to describe the dynamic buckling stability is obtained. Finally, the structure analysis program for the stabilization reliability of the integer structure can be obtained.4) The method of the stability reliability analysis of truss and shell structure system is researched, the stability characteristic equation and the instability safe margin are obtained. Finally, the reliability index of safe margin is obtained. According to the result of simulation, the structure integer stability reliability index in the different direction is resolved, finally, the structure integer stability reliability index at the time of the supercavity vehicle steadily moving is obtained. According to the result of the simulation, the structure analysis is processed by using the new constraint method, thus, the result is according with the fact much more.5) The dynamic transmutation of the asymmetry thickness is forecasted by the model established with shell. The considered buckling loads include compressive forces corresponding to propulsion and drag at the nose of the vehicle, and a concentrated axial force corresponding to the drag experienced by the vehicle on its afterbody. The stability performance of plain shells is compared to the tapered shell. The tapered configurations are then optimized to enhance the overall stability characteristics of the vehicle, based on the integer stability reliability, while minimizing the required added weight.