Abstract: The parametric finite element model(FEM) of wedged-ring joint structure is established using ANSYS parametric design language(APDL). For enhancing the joint structure strength, the wedged-ring dimensions are taken as design variables, and the maximal stress ratio is taken as a objective function to establish the first optimization model. Then, for obtaining the equal strength joint structure, the second optimization model is established using the quadratic sum of stress ratio subtracters as another objective function. Two optimization problems are solved using first order method based on conjugate gradient method. The first optimization result shows that the maximal Mises stress of the optimum structure is 21.1% less than that of the initial structure, and that safety coefficient of structure raises to 1.37 from 1.08 under tensile loading. In addition, the second optimization result shows that the objective function decreases to 0.067 from 0.600, and stress ratio of structure components approaches each other. Thus, the first order method combined with nonlinear FEM can be used to design the joint structure and obtain the satisfactory optimization result.

Key words: Conjugate gradient method, Finite element model(FEM), Optimization design, Wedged-ring joint structure