Structural Optimization Design Of Ideal Functional Material Components

Ideal Functional Material Components (IFMC) are the heterogeneous objects which are designed for the best functional use, and constructed by homogeneous materials, composition materials, functional gradient materials (FGM), period functional meso-structure (PMS) and even embedded micro-device. They can not only economize resources but also improve the whole quality and satisfy the increasing functional needs of material and products by the interactivity of primary materials and the perfect combination of geometry, material and quality. It is believed that IFMC will have a great deal of applications in aviation, aerospace, bioengineering and mechanical electron. IFMC are typical heterogeneous objects designed on demand, and the design and manufacturing method of traditional homogeneous components is no longer applicable to IFMC. Therefore, it is necessary to develop a whole new theory and method for designing and manufacturing of IFMC.The IFMC's design is the integral (merge) design of the external geometric topology, shape and internal material constituent, meso-structures under satisfying the component's performance requirement. And it is a key loop in the digital concurrent design and manufacturing of IFMC. This dissertation starts the research mainly from the continuous structure optimization design and the material optimization design of IFMC. Based on thus, the design method of IFMC is constructed and applied to the optimization design of calibrator cooling systems.In the paper, the continuous structure optimization design based on element free Galerkin method (EFGM) is discussed firstly. The advice on selecting weight function and its parameter is presented by numerical examples. Taking the material densities at gauss points in the integration cells as design variables, the topology optimization designs for stiff structure, compliant mechanism and engineering components with complex shape constraints are investigated, respectively. The application of EFGM is more convenient to the discretization of initial design domain and improves the computing precision of design results. The synchronized motion of design domain and the nodes in it is carried out and the distortion of mesh presented in the process of shape optimization can be completely avoided by integrating the EFGM into the shape optimization and building the function mapping relation between the nodes' coordinates and boundary profile variables. Based on the continuous structure topology optimization, restricting the holes' shape, a topology optimization model with regular geometric constraints for continuum structure is presented and solved by an evolutionary structure optimization method based on interval relaxation. On this basis, the design method of simultaneous shape and topology optimization for continuous structure with circular holes' constraint is achieved. The proposed method solves the problem that the geometric relevancy of optimization variables can't be established easily in the topology optimization.The fictitious nodes are introduced in the IFMC's design domain and the volume fractions of them are served as IFMC's material feature. The optimum solution of fictitious nodes' volume fractions is obtained adopting improved real coded genetic algorithm. The material optimal result is done curve/surface fitting using B-spline interpolation technology so that IFMC's material distribution is continuous and smooth.Then, based on the continuous structure optimization design and IFMC's material optimization design, the design method of EFMC is constructed. The geometry boundary feature is expressed by the coordinates of a set of key points; fictitious nodes are introduced so that material feature can be denoted; topology feature is defined using the number of holes in the component and the function mapping relations of material feature, shape feature and topology feature are also established, which can easily describe the everchanging design model. For the concurrent design for geometry with material of IFMC with definite topology configuration, a new approach combining the method of feasible direction (MFD) with the genetic algorithm (GA) is proposed. The changing of topological configuration is realized by hole-inserting policy based on the sensitivity analysis of objective function. Thus, the optimal geometric topology, shape and material distribution of IFMC can be got by the concurrent design for geometry with material of IFMC with a series of topology configurations, which solves the coupling problem of geometry with material and realizes the integrated design of material and structure for IFMC.Lastly, the design method of IFMC proposed in the paper is applied to the optimization design of calibrator cooling systems. The homogeneous calibrator and ideal material calibrator are considered respectively. From the optimal results' analysis and comparison, we can see that the ideal material calibrator improves greatly the cooling uniformity of plastic profile by changing the cooling channel's location, size, number and adjusting calibrator's material distribution.