Research On The Dynamic Response And Protection Of Ship Hull Structure Under The Action Of Sea-launched Impact Load

Rocket launch at sea is based on offshore platforms,ships and other equipment as the launch site,the so-called "cold launch" mode,the rocket ejected from the launch tube,in midair ignition launch.The impact load formed by the ejection of the rocket will trigger the dynamic response of the surrounding structure,and if not controlled,it will lead to the damage of the local structure and the drastic change of the total longitudinal strength.At the same time,although the probability of accidental fall collision due to rocket mid-air ignition failure is low,the engineering accident caused by it poses a great threat to the safety of personnel and is a key factor limiting the reliability and safety of offshore launch platforms.The essence of the safety of the offshore rocket launch platform is the energy transfer and feedback of the structure under the action of arrow impact.Therefore,based on the engineering practice,this paper studies the structural dynamic response characteristics triggered by the impact load of rocket ejection and accidental fall collision,and intends to investigate the influence of structural parameters and the initial state of collision on the structural dynamic response of the hull,in order to clarify the hull dynamic response law under the action of impact,aiming to provide support for the safety research of the offshore launch platform.Based on the analysis of the current research status of scholars at domestic and abroad on the structural response of ship hull under impact load,fall collision and impact protection,this paper determines the dynamic response of ship hull structure under rocket ejection impact by explicit dynamics analysis method,and uses Ls-Dyna program Lagrange algorithm to deal with rocket accidental fall collision problem,so as to point out the direction of the research method and technology relying on this paper.Firstly,the basic theories and related methods involved in this paper are described,and the numerical simulations are compared with the experimental test results to verify their validity.Secondly,the time domain curve of the equivalent load of the rocket ejection impact is constructed,and the dynamics model of the offshore rocket launcher is established based on the acoustic-solid coupling theory to investigate the dynamic response of the structure under the rocket ejection impact.The stress,deformation and vibration acceleration of the hull are analyzed from the time domain perspective to analyze the structural vibration and transmission law in each region of the ship.At the same time,the existence of weak areas in the amidships structure is determined,and then the influence of parameters such as plate thickness and profile size of the local structure in the rocket launch area on the dynamic response characteristics of the ship is investigated,and the vibration protection of the local structure amidships is briefly elaborated.For the analysis of rocket accidental fall collision impact response problem,based on the analysis of the collision motion attitude of the arrow hull,the hull structural stress,deformation and vibration acceleration of different compartments of the hull under the time domain angle are explored to clarify the degree of structural response triggered by the collision impact.After that,the impact of initial factors such as collision angle and collision position on the structural dynamic response of the hull is investigated by probabilistic analysis of the rocket collision position.Finally,based on the structure of different longitudinal truss configurations,the influence of the structural form and the participation of the new material of aluminum foam on the impact resistance of the protective structure was investigated.This paper is based on the study of structural dynamic response under the impact of rocket ejection and arrow accidental fall,to clarify the weak areas of hull structure and vibration transmission law,to further explore the influence of characteristic parameters on structural impact response,and to analyze the impact resistance of protective structure,aiming to provide reference basis and technical support for the safety of offshore rocket launch platform.