Research On Wedge-Ring Connection Structure Reliability-Based Design Optimization

Wedge-Ring Connection Structure was widely used in shell connection of torpedo, rocket, astronautic vehicles and underwater vehicles. The smooth surface of shell could improve the aerodynamic or hydraulic performance of the above productions under the condition of high speed, and the reliability under external loads was directly related with the realization of system functions.Under the engineering demand, the stress of wedge-ring connection structure was studied by the elastic-plastic finite element method in this paper, and the failure mode of the structure was given. The thought of design by analysis was took in and the failure condition was provided. On this basis, the function of quadratic response surface was constructed by finite element orthogonal experiment, and then optimization model constrained by the reliability was established and solved. The more miniature structure was obtained to satisfy different reliability requirements, and this new method could be provided to the similar structure design.The main researches included:1) The weakness of wedge-ring connection structure was the cross section at the root of shell wedge-ring groove, where there were bending stress induced by the stress concentration and structure deformation.2) The root of wedge-ring groove was yielded firstly and the local plastic yielding should not induce the failure of whole structure. When the yielding extended to the whole cross section, the structure should collapse plastically.3) The main reasons caused the failure of wedge-ring connection structure were general primary membrane stress and primary bending stress of the dangerous cross sections. The criterion of failure was confirmed and the experimental research had shown the criterion should be apply in the plastic material.4) The function of quadratic response surface with some parameters was constructed, and the analysis shown the length L1 of rabbet at the outlet of shell was the primary influencing parameter of structural stress response.5) The result of reliability optimization and verification had shown the optimized structure was better than original design, and it balanced the requirement of reliability and the miniaturization of structure.