Limit And Shakedown Analysis Of Structures Based On Improved Temperature Parameter Method

Limit and shakedown analysis of structures is a significant branch of plastic mechanics. Temperature parameter method is one of the effective methods. It solves the problem with linear programming method using the elastic analysis programs and the linearized yield condition. Despite the versatility of this method from the perspective of computational mechanics, it is difficult to solve the complicated problems or analysis three-dimensional structures. In order to overcome this difficulties, the main content of this paper is as follows:Firstly, the program implementation of temperature parameter method is given based on the commercial software ANSYS and SiPESC.OPT. ANSYS is used to perform the elastic analysis, and then the combination of the genetic algorithm and sequential quadratic programming algorithm in SiPESC.OPT is used to calculate the optimization problem. A classical numerical example, which is a plate with a hole under the bidirectional tensile, is analyzed. Results are compared with relevant literatures to verify the feasibility of the program implementation.Secondly, a modified algorithm, which is in conjunction with the non-uniform rational b-spline (NURBS) surface fitting, is presented to reduce the number of variables in the optimization problem. While there are lots of elements in the finite element model of the structure, considering the scale of the optimization problem, the temperature parameter method may face computational scale problem. The modified algorithm become a suitable method. A numerical example is also analyzed to demonstrate the feasibility of the introduction of NURBS.Thirdly, an improved method is proposed which directly employ Mises yield condition without any approximation in the temperature parameter, therefore it can be applied to three-dimensional problems. In traditional method, the yield condition is linearized and this restricted its application to engineering problems. The paper overcome the restriction. A cylinder under the inner pressure is analyzed. Results are compared with analytical solution to verify the feasibility of the improvement.Finally, the improved temperature parameter method is employed to conduct the shakedown analysis of pipeline with part-through slot subjected to internal pressure.Based on the finite element software Ansys and optimization software SiPESC.OPT, the paper investigates the numerical algorithm for shakedown analysis, its technical ways are convenient for engineering applications. The proposed method is in conjunction with NURBS surface fitting and reduces problem scale, therefore it can applied to 3D problems. Numerical examples are employed to verify the method.