Research On Dynamic Response Of Submarine Launched Missile

As science and technology developed,research on vibrations of submarine-launched missile attracts more and more attention.In the process of launching,transverse vibration of its structure directly affect the success of emission.Therefore,research on the vibration of submarine launched missile is of great importance.The movement of missile can be modeled as axially moving free-free beam.In this paper,axially moving beam is being studied,the dynamics model of an axially moving free-free beam is established,the differential equation for transverse vibration are derived using the Hamilton principle,and the effect of axial force and gravity are considered.The equation is discreted by finite element method,and the numerical simulation is executed based on Matlab.Through the numerical simulation,the effect of axial force and concentrated mass to the transverse vibration of the beam is studied.The results show that with the increase of axial thrust,the first natural frequency decreases first and then increases,second order natural frequency decreases.When the force reaches a certain value,the two frequencies are equal,the modal of the two order frequency corresponding to the same.Without the effect of axial thrust,the size and position of concentrated mass have influence on the transverse vibration frequency and vibration mode shape of the free-free beam.The greater is the mass concentration,the smaller are the natural frequencies;the concentrated mass is close to the vibration node,the natural frequency is high.When the axial thrust is considered,if the concentrated mass is placed at some special position,the critical frequency of free vibration of free beam will not change.This paper also introduced the method to calculate the fluid added mass,establishing the model of a submarine launched missile transport underwater.The vibration characteristics of the model under water is studied.The results show that,due to the fluid effect,the natural frequency of the missile structure is significantly reduced,and the frequency of lower order decrease greater.Based on the Ansys Workbech software,the simulation analysis of the submarine launched missile is completed.By the means of Fluent and Transient Structural,the Fluid Solid Interaction realized.The flow field of the fluid is studied,and dynamics of the submarine launched missile when launched from different depth are studied.The result shows that when launched from different depth with the same speed and thrust,the displacement,velocity and deflection angle of the missile have the same variation.In this paper,an axially moving free-free beam and the process of submarine launched missile are studied.The results in this paper may of a certain reference value,when the vibrations of a submarine launched missile,a rocket or other axially moving structures be studied.