Study On Mechanical Properties Of Stitched Sandwich Plate For Vessel Radome

The stealth performance of modern ships occupies a large part of the combat advantages of ships,and the mast is often inferior in stealth performance because it is usually located at the highest point of the ship.In order to meet the operational requirements of modern naval battles,the closed composite masts of ships have gradually replaced traditional truss mast.The outer cover of the closed mast is the radome.Most of the mast radome structures of ships use composite sandwich panels.Although the sandwich panel has the characteristics of high specific strength and stiffness,sandwich panel has poor load transfer ability,weak interlayer performance,and prone to delamination.This paper designs the stitching method to enhance the interlayer performance of the sandwich structure,next studies the effect of the stitching method on the basic static characteristics of the sandwich panel,and then explores the approximate influence of stitching parameters on the structure.In this paper,two types of stitching reinforced sandwich panels were designed for ship mast radomes:one was a vertical integral stitching sandwich panel,and the other was a diagonal integral stitching sandwich panel.Considering the filtering characteristics of the radome,the 'sandwich panel was made of composite fiber reinforced resin sheet,and the core layer was made of polymer foam material.In the calculation,the composite material panel was equivalent to a homogeneous material.The main research contents were as follows:1)In this paper,the research results of the closed stealth mast at home and abroad were summarized.The structure of typical stealth integrated mast and the interlayer toughening technology of existing sandwich structure were referred,and proposed the stitching reinforced sandwich panel of mast radome.Combined with the existing resources,the general flow of finite element analysis method was given.2)The meso-scale model of the vertical overall stitching sandwich panel and the diagonal overall stitching sandwich panel were established,which set reasonable contacts and divided the fine mesh to ensure reasonable results.The model considered the interaction among composite material panels,olymer foam core layers and fiber yams.According to the mechanical characteristics of the fiber yarn itself,the APDL command flows were written to set the fiber yarn as the cable unit.The model reflected the mechanical characteristics of the stitching to strengthen the sandwich panel.After reasonable simplification,the workload of the computer has been greatly reduced.3)The composite fiber-reinforced resin panel was equivalent to a homogeneous panel through the mixing law,ignoring the interaction between fibers and sutures,and reducing the difficulty of research.Based on the Reissner shear theory,the sandwich plate was analyzed,and the basic equations of the sandwich plate were given,which provided the theoretical basis for the finite element analysis.The stitching reinforced sandwich plate was fabricated and tested.The test results were compared with the finite element results to verify the effectiveness of the modeling method.4)Under the three basic stress states of stretching,bending and shearing,the method of vertical overall stitching and diagonal overall stitching were compared to study the improvement performance of the sandwich structure.Both two stitching methods can effectively improve the stress field distribution.Next,the variation trend of the influence of the suture parameters such as the vertical overall suture step,the diagonal suture angle,and the diagonal suture step on the mechanical properties of the overall structure under different stress conditions was studied.Under the condition of a certain thickness of the structure,the stiffness and force transmission performance of the structure can be enhanced to varying degrees.