Research On Combinatorial Model Method Of Forecasting Impact Environment Of Ships Subjected To Underwater Explosion

Before the ship equipment is put into use,it is required to evaluate the impact resistance of ship equipment.The impact environment of ship is the standard input that GJB stipulates,and it is very necessary to predict the impact environment of ship accurately.At present it has been getting more and more attention by the national navy to forecast impact environment of ship,and carrying out the cabin test is a method to study the ship impact environment.As the cabin test model is easy to obtain,and test is convenient and it is easy to implement,so the researchers expect to get the whole ship shock environment by cabin test.But the cabin is a part structure of the ship,results of cabin test and actual ship test are quite different,it includes the inherent differences of impact environment between the cabin and the ship,and it also includes the differences of impact environment caused by impact spectrum fall that equipment installation may cause.Therefore,this paper mainly focuses on these two issues to study,it mainly contrast and analyze the impact environment of the cabin and the whole ship by theory and numerical calculation,the aim is to provide a method to predict impact environment with converting the cabin to the whole ship,the specific contents are as follows:Firstly,to analyze the differences of impact environment between the cabin and the ship,it takes two typical models including underwater cylindrical shell and surface ship as examples,and selects a number of cabin models,to calculate impact environment of cabins and the two whole ships subjected to underwater explosion by numerical simulation.Then it compares and analyzes the impact of environment multiple local cabins and the whole ship,to explore the differences of impact environment between cabins in different local and the whole ship.Secondly,for the problem that there are differences of impact environment between the cabin and the ship,it used the relevant theory to analyze the cause of the discrepancy,and gets responses in different frequency bands by decomposing impact response.Then it combines with the principle of frequency division of impact environment to analyze low-frequency response components of the cabin and the whole ship.It is considered that the difference of the low-frequency response components between the cabin and the whole ship is the main reason for the difference of impact environment.Thirdly,for the problem that to predict impact environment with converting the cabin to the whole ship,it summarizes the method of forecasting impact environment in low frequency band,and combines with the theory analysis results of impact environmental to presents a method of forecasting impact environment of the whole ship based on the impact environment data of cabin.Then it compares and analyzes the numerical results and prediction results under various underwater explosion conditions,and it is suggests that the combinatorial model forecastion method can be used to predict the impact environment with converting the cabin to the whole ship.By carrying out the impact experiment of local structure and the overall structure model,it is verified that the local structure can approximately replace the medium-high frequency impact environment of the whole structure.Finally,for the problem whether the shipboard equipment installation can cause the impact spectrum of impact environment to fall,it creates multiple device models by finite element simulation to investigate the impact environment of the ship subjected to the underwater explosion.Then it discusses the influencing factors of the spectrum fall by changing a variety of parameters.By exploring the phenomenon of spectral fall when equipment is installed in different deck parts,it proposes a parameter of the quality factor for the revision of the reduction factor.