Dynamic Response Analysis And Simulation Of Cylindrical Shells And Similar Structures Under Impact

The major work of this paper is developed on the research project "Dynamic Characteristics Analysis and Simulation of Torpedo's Fusee-trigger" (sponsored by CSIC-No. 705 Research & Development Institute). The dynamic characteristics of elastic plates subjected to transverse impact and non-linearly elastic & elasto-plastic cylindrical shells under axial impact loading are investigated theoretically. Moreover, the dynamic response of a torpedo impacting the target plate or falling into the water is analyzed and simulated by Finite Element Method. First the relative researches of plates and cylindrical shells under impact loading are reviewed comprehensively. Concerning the impact problems in practical engineering, the effect of impact velocity and target plate's thickness on the plate's dynamic response is described. And the application of CAE techniques in the simulation of structure impact is introduced in brief. A finite difference technique is employed to predict the transient dynamic response of elastic plates under the impact of a mass. The equations of motion are based on the classic theories of thin plates, and Hertzian contact law is adopted to calculate the impact force. The applicability of the present numerical approach is successfully verified through the comparisons with results available in the literature. Numerical results demonstrate the effect of impact velocity, local radius and mass on the impact force and contact duration.The numerical increment method is offered to analyze the axisymmetric response of nonlinearly elastic cylindrical shells under axial impact. The strain-stress relations are described by the Ramberg-Osgood representation, and the equations of motion are based on the Karman-Donnell relations. The Runge-Kutta method with respect to time and the finite difference method with respect to the spatial coordinate are employed to derive a solution; Numerical results demonstrate the effect of the material nonlinearity and boundaries on the deflections and dynamic buckling behavior of cylindrical shells. The elasto-plastic dynamic response of cylindrical shells with initial geometry imperfections under axial impact is analyzed by the method mentioned above. The constitution relations of materials are described by incremental theory, and the control equations are also based on Donnell's shell theory. The effect of axial and circumferential imperfections on the displacements of cylindrical shells is discussed.The next, based on the above analysis, Using MATLAB/SIMULINK, the dynamic response of plates subjected to transverse impact and cylindrical shells under axial impact loading is simulated.Finally, with ANSYS/LS-DYNA code, the simulation and analysis of the impact and fluid-solid coupling problems are discussed. According to Finite Element Method, the torpedo is considered as a discrete mass system in terms of 3D solid element with initial velocity. The practical engineering calculation examples illustrate the availability of the proposed method.