Design And Mechanical Property Analysis Of H-type Hybrid Joint

Composite materials are widely used in ship superstructure and its internal structure,This will lead to the reliability problem of the connection between the composite material and the steel main hull.The connection structure is the weak link of hull structure,and its performance characteristics are related to the safety of the whole ship.Therefore,based on Marine composite material and the metal connection problem as the research background in this paper,and by designing hybrid joints of new composite materials and metal,the strength characteristics,failure mode,fatigue life and other mechanical properties of joints under static and fatigue loads are studied.It provides useful reference for the design and practical application of ship composite structure.Firstly,the configuration design of hybrid joint is carried out.Through comprehensive consideration of the material selection and design principles of hybrid joint,this paper finally chooses plane woven glass fiber composite material panel,PVC foam sandwich,Marine 921 A steel as the main joint materials.In this paper,the double-shear bolt connection structure is adopted,and based on the sandwich structure theory,the dimension design of the joint is carried out according to the design standard of the bolt connection structure geometric parameters.Finally,the configuration design of H-type hybrid joint is completed.Then,the finite element simulation of H-type hybrid joint is studied.Using the finite element analysis software Abaqus,the finite element model of h-type hybrid joint was established,and the three-dimensional Hashin damage criterion applicable to the planar braided composite material in this paper was defined,and the stress distribution,ultimate bearing capacity and damage failure mode of the joint were obtained.Then the static characteristic of the joint is studied.The ultimate bearing capacity,failure failure mode and strain distribution obtained by three sets of static test pieces are all the same.By comparing the static test results with the finite element results,it is proved that the finite element model established in this paper can better predict the strength and failure mode of the joint,and then the simulation analysis on the influence parameters of the joint strength is carried out.Finally,the fatigue characteristics of H-type hybrid joints are studied.In this paper,three groups of fatigue test pieces are tested under three levels of equal displacement control under different loading levels,and the load-cycles curves and fatigue damage modes of joints under different loading levels are obtained.The fatigue failure modes of the three groups of joints are the same,all of which are the lamination failure of laminated plates and the shear failure of PVC foam.Then the DIC method was used to measure the surface strain of the specimen,and the variation rule of strain with the number of cycles was obtained.Finally,the changes of residual strength and stiffness of joints after fatigue loading are obtained through residual strength test.