Mechanical Analysis And Joints Design Of Integrated Composite Superstructure

With superior stealth performance and mechanical performance, composites have been widely applied in advanced national defense and military fields. Integrated composite superstructure adopted in US destroyer DDG1000 is the latest achievement in the application of high-performance composite materials in surface warship. It attracted much attention since it come out. The research on high performance marine composite materials in our country started relatively late compared with western countries. To realize the application of integrated composite superstructure on domestic vessel, except for molding process, three questions need to be solved. The first one is longitudinal strength of composite superstructure,and the second one is structure design method, and the last one is connecting problem between composite superstructure and steel hull. The calculation research is carried out to focus on above three questions to prove that application of integrated composite superstructure in large-scale surface ship is feasible.In order to research the response characteristics of composite superstructure in longitudinal bending, longitudinal strength of composite superstructure in different length is check by FEA. It prove that composite superstructure will not be damaged under four different design conditions. And then distribution curves of vertical stress and horizontal shear on connections and bending normal stress on midship section are obtained by this method.Effectiveness analysis of superstructure is developed to obtain relation curves between effectiveness and length of superstructure by comparing composite superstructure with steel superstructure. The simulation results indicate that the level of composite superstructure joining in gross longitudinal bending is much lower than traditional steel superstructure.Reducing the quality of overall structural as much as possible is the goal of composite structure optimal design. Based on the stress characteristics of the composite superstructure, a method for the optimization of structure is presented in this paper. According to this method,the weight of optimal composite superstructure reduces 40% compared with steel superstructure and the reduction effect is obvious. It could provide the technical basis for the application of composite superstructure on surface ships.Due to the characteristics of progressive failure, the ultimate strength analysis and damage mode analysis of composite structure are far more complicated than steel structures.Stiffness degradation reduction plan is drawn up according to the Hashin failure criterion.APDL language is used to realize secondary development of ANSYS to calculate maximum load-bearing capacity of composite structures by the method of progressive failure. Accuracy of the algorithm will be validated by comparing with experiment data of single-shear two-fastener bonded-bolted hybrid joints tensile test. This new method is aimed at providing a technology support for the failure calculation of composite materials.Design effective and reliable connecting structure between composite and steel is the biggest difficulty that restrict composite superstructure application in ship. The form of?-shape double-shear two-fastener connection is adopted as final design considered advantages and disadvantages of various connection forms and connecting structure, and rationality of the design would be verified by intensity assessment under design load. The aim of the research is to provide a reference for the application of composite superstructure on ships.