Research On Load-reducing Characteristics Of Water-entry Vehicle With Large Scale And High Speed

Research of load reduction problem when vehicle enter into water at high speed has been a hot and difficult problem both in China and abroad.When the vehicle enter into water at high speed,it will produce a great impact force at the moment vehicle impact the surface.This force will damage the the body of vehicle and cause the device inside failure.In order to ensure the safety of the vehicle which enter into water at high speed,measures which can reduce the impact force must be taken.Current research on the problem of the structural response and the ballistic characteristics of water-entey vehicle mainly concentrated on large size objects such as torpedo low speed and small size objects such as projectile at high speed.Summarizing from the existing literature,there are little discussion on the load reduction problem of large size objects entry into water at high speed.The results of these study are difficult to support the engineering application.It still need to research the problems such as the fluid dynamic characteristics,the cushion nose cap structure and material design.Based on the previous research,in this paper,we use the euler-lagrange coupling algorithm method(CEL method)to establish the solid-air-water coupling model and analyze the dynamic response problem in the process of water entry.With MK46 torpedo as the vehicle model,design the shape,size,material and other parameters of each part of the cushion nose cap to provide references for the engineering application.Firstly,in this paper,the influence of the shape and size of the head cover on the impact load is discussed.The fracture process of the head cover is analyzed,and the design points of the shape and size of the head cover are expounded.The results obtained by numerical simulation are verified by small scale experiment.Secondly,by comparing the buffering effects of aluminum foam with different relative densities,the law of decreasing load effect with different relative density of aluminum foam is obtained.This paper discusses the tendency of the parameters of the optimal aluminum foamed material changing with different water inlet velocity,and expounds the key points of the optimal design of the parameters of aluminum foamed material under different water inlet velocity.Finally,the load reduction effect of cushion nose cap is verified when vehicle enter into water under vertical and oblique conditions.The influence of the cushion nose cap on the trajectory of water entry in the case of oblique conditions is discussed.It is verified that the cushion nose cap has good effect for reducing load and applicability under both vertical and oblique water entry conditions.