Damage Characteristics Of Composite Sandwich Structure Subjected To Underwater Explosive Shock Wave Loading

Ships,submarines and other naval equipment are often threatened by underwater weapons.In addition to reducing the probability of naval equipment being discovered by enemy detection systems,they are also required to remain viable after being subjected to underwater explosions.Fiber reinforced composite materials such as glass fiber have the advantages of low magnetic properties,high specific stiffness,and excellent corrosion resistance,and the foam material has the advantages of ultra-light weight and high energy absorption efficiency.The composite sandwich structure combined with the two is more and more widely used in the fields of ship protection and mine detection,etc.Therefore,it is necessary to carry out research on the damage characteristics under underwater explosion load.Based on the finite element idea,this paper studies the composite clip of underwater explosion shock wave load by writing the VUMAT(User-define Subroutine Material)subroutine which defines the mechanical behavior of composite materials,combined with the CEL method and the acoustic-solid coupling method in the commercial software ABAQUS/Explicit.The damage characteristics of the core structure are intended to provide a theoretical basis for improving the protective performance of composite ships.Since most of the finite element software only supports the numerical simulation of the two-dimensional shell element composite,and ignores the influence of the unit transverse shear,it is difficult to completely control the composite material in the numerical study of the damage characteristics of the composite under underwater explosion load.Damage.In this paper,based on the three-dimensional mechanical properties of fiber reinforced composites,the VUMAT subroutine of user-defined materials is established.The subroutine mainly includes the orthotropic three-dimensional mechanical constitutive model of composite materials and Hashin for determining the damage initiation.The failure criterion and energy-based progressive failure model,combined with ABAQUS/Explicit,a series of numerical simulations verify the applicability of the model.In the underwater explosion shock wave loading,taking into account the many shortcomings of the actual explosive experiment,and based on the underwater explosion shock wave propagation characteristics and stress wave theory,an underwater explosion shock wave simulation device is described,by changing the shrapnel quality,initial velocity and Conditions such as materials simulate the effects of underwater explosion shock wave loads.The experimental setup is simple and safe and can be performed in the laboratory.In this paper,the finite element model of the simulation device is established according to the foreign literature.The CEL method in ABAQUS software is used to simulate the flow-solid coupling process of water and structure and the generation of shock wave.The numerical results are compared with the theoretical and experimental results.The validity of the numerical model is established in this paper.The criteria for evaluating the performance of a composite sandwich structure are its resistance to deformation and energy dissipation,and their close relationship with the material and design parameters of the sandwich structure.It is difficult to accurately measure the energy consumption and damage of the structure under the experimental conditions,and the numerical simulation method can make up for the lack of experiments.Based on the finite element model of the simulated underwater explosion shock wave simulation device,the deformation of the sandwich panel of the composite material under the shock wave loading conditions of different strengths,the thickness ratio of the core layer of the panel,the density of the core layer and the density gradient of the core layer are discussed.The effects of damage and energy absorption.Finally,based on the great threat of mines during sea warfare and the importance of marine demining,according to the structural shape of a towed minesweeper,a cylindrical finite element model of the sandwich structure was established,and the underwater solidification coupling algorithm of ABAQUS was used to analyze the underwater.The dynamic response of the structure under the shock wave of the medium and far field explosion provides a reference for understanding the impact resistance of the minesweeper.