Research On Dynamic Response Of A Axially Moving Free-free Beam

In the modern war, submarine launched missile attracts more and more attentions in the world. The vibration of its structure may directly lead to success or failure in the launching process. Therefore, research on the vibration of submarine launched missile is of great importance. Submarine launched missile is simplified as a free-free beam with lumped mass.An accurate analytic method for longitudinal vibration of free-free beam with lumped mass is given. The accurate value of natural frequency and principle mode is obtained from the basic beam vibration equation with Laplace method, and the relation between longitudinal vibration characteristic and location and magnitude of lumped mass. The dynamic response under the harmonic force for longitudinal vibration of free-free beam with lumped mass is investigated by using assumed mode method.On the basis of lumped-mass method, lateral vibration characteristics of free-free beam with lumped mass. The first two order natural vibration frequency and principle mode of the free-free beam are given, and MATLAB software is used to curve fitting for the first two modes. The dynamic response under the point force for lateral vibration of free-free beam with lumped mass is obtained based on assumed mode method.The Hamilton principle is developed to derive the dynamic equations of an axially moving free-free beam in this paper, and the equations are discreted by finite element method.Through numerical simulation, the influence of location and magnitude of lumped mass on the longitudinal and lateral vibration of a free beam is analyzed, and the same conclusion compared with the previous paper is obtained. The dynamic response for longitudinal and lateral vibration of free-free beam with lumped mass by Newmark method.The fluid-solid coupling system is established by ansys workbench in this paper, and the water-exit process of free-free beam is simulated. The variation of displacement?velocity and the fluid force acting on free-free beam at different depth launching are obtained,and the stress distribution on free-free beam at different time points are analyzed.