With Minimum Stress Concentration, Gap Shape Optimization Method

There are a number of factors to influence the material or structural's fatigue strength, and the structural design gap or the fillet which cause the stress concentration have the remarkable influence to the fatigue strength. It is a task of shape optimization in some sense to improve the characteristic of structure, which it is more to minimizing stress concentration, to improve stress distributing status, by changing the geometry shape of structure regions, and requiring certain physics value to meet some condition in the boundary. An efficient parameterization method is proposed to obtain optimal gap shape for minimum stress concentration, and the intensive study of the method is implemented.Firstly, the development of structural optimization is briefly reviewed. Structural optimization problems are concluded into three levels, one of which is shape optimization. The main study of shape optimization is reviewed. The content and method of the thesis is brought forward.Then, the text introduced the general optimization design concept and the mathematical model briefly. Regarding this topic research's shape optimization problem, elaborated two kind of optimized algorithms with emphasis: Penalty function method and conjugate gradient method. Simultaneously introduced finite element analysis software ANSYS and its optimized method, and discussed some of the attention and skills when using this method.Next, the boundary shape for a gap is described by"super circular"or"super elliptic"parameterized equations. the parameters of the curve are chosen as the design variables of shape optimization, the minimizing maximum Von Mises stress of globe structure is chosen as the object function of optimization. Using this parameter optimization method, this text discussed two typical gaps's shape optimization problem, and has confirmed the usability and the validity of the parametrization optimization method.Finally,the goal of shape optimization is to obtain optimal dedendum transion curve for minimum bending stress using parameterized geometry models. The boundary shape for transion curve is described by generalized elliptic function. The gear model is founded by ANSYS, and adopting first step optimization in ANSYS optimize the dedendum maximum Von Mises stress. As compared to the known solutions in the literature, it was shown that extremely good results could be obtained while using the proposed parameterized equations.