Analysis Of Underwater Explosion Load Transfer And Shock Environment Characteristics Of Trimaran

As a new type of high-performance vessel,the trimaran has become a major direction for the development of naval vessels in various countries since its birth.There are some advantages such as good overall arrangement,low detectability,strong survivability,and good high-speed seaworthiness due to structural characteristics of the hull of trimaran.At present,the research on trimaran is mainly focused on the hydrodynamic and structural design,but less on the distribution characteristics of the impact environment under the underwater explosion load.To evaluate the vitality of trimarans under battlefield conditions,and to promote trimarans to further military and actual combat,the analysis of the distribution characteristics of its impact environment will be indispensable.This article conducts research on the distribution characteristics of a certain type of trimaran’s impact environment by the acoustic solid coupling numerical method,focusing on the comparison of the differences of the trimaran compared with the conventional ship in the three aspects of explosion load transfer,impact environment distribution and the impact of shipborne equipment on the impact environment of the ship,and probes into the causes of the differences from the perspective of the ship structure.The influence of different parameters of impact environment on the response of shipboard equipment to impact assessment is discussed.The purpose is to provide a certain reference for the impact resistance design of the trimaran and its shipborne equipment in the future.The full text is as follows:Firstly,the process of underwater explosion,the calculation method of related loads and the characteristics of trimaran are introduced.Aiming at the problem of underwater explosion load transfer in water and dynamic response of structure under explosion load,the finite element model is established to verify its validity.Secondly,in order to explore the transmission characteristics of underwater explosion load along the ship’s characteristic direction,the equivalent structure of the ship’s multi-layer plate frame is established based on the law of stress wave transmission,and the influence of explosion load parameters and structural parameters on the transmission characteristics of stress wave in the equivalent structure is analyzed.In order to verify the relevant inference,the numerical model of single hull ship and trimaran under underwater explosion condition is established.Through empirical mode decomposition of impact response at each position of typical section of them,the differences of application,transmission path and distribution characteristics of explosion load between two hull types are analyzed.The main reason for the difference is that the main structure of trimaran is long and thin,and there are pieces and connecting bridges in trimaran.Then,the influence of four kinds of parameters such as load type,calculation time,structural damping and response signal truncation frequency on the calculation results are analyzed.After the calculation parameters are determined,the differences of the distribution of the impact environment along the ship’s characteristic direction under different attack angles,impact factors,explosion positions and other working conditions are calculated,and the relationship between the load distribution and the impact environment distribution is analyzed based on the empirical mode decomposition results of typical positions.According to the distribution law of impact environment and stress nephogram of typical section,it is found that the distribution of severe impact environment area is consistent with that of stress concentration area,and the weak area of impact resistance of trimaran structure is determined.Finally,the paper studies the anti impact assessment of the equipment based on the impact environment of the ship from three aspects: the spectrum drop caused by the shipborne equipment,the difference of the calculation results when using different assessment methods and the correction of the input load.By installing the simplified equipment model in the typical position of the trimaran,the influence degree of different equipment parameters on the spectrum drop phenomenon is analyzed.After determining the influence degree,the difference of the assessment results between the ship equipment coupling assessment method and the non integrated assessment method based on the impact environment of the ship is analyzed with a typical rigid installation of the ship equipment as an example.In order to correct the difference of assessment results,the influence degree of various parameters in impact environment on assessment results is analyzed,and a set of correction factors for the input load of rigid installation equipment is given,and the applicability of the correction factors under the conditions of medium and far field explosion is verified.