Research On Design Space Exploration And Coordinated Decomposition Methods For Complex Product

Complex product (such as areoplanes, ship, automotive vehicles and machine tools) design optimization involes multi-field and multidiscipline that act and couple with each other, which makes the design optimization quite complex and hard to be computed. Multidisciplinary design optimization (MDO) is a frame with system synthetical optimization, for solving above problems. Due to validity and practicability of decomposition and optimization, MDO has become focused on, gradually. Complex product design space exploration and coordinated decomposition methods are the main ways to reduce design space and huge computation and have been attractted great attention. In the process of complex product design optimization, research on design space exploration and coordinated decomposition is interdisciplinary, thus, huge knowledge is necessary. The development of design space exploration and coordinated decomposition is prohibited and challenges present researches.In this dissertation, based on the design space exploration and coordinated decomposition, mechanics of complex product design optimization is studied. A research system of design space exploration and coordinated decomposition is constructed, including the design space exploration method based on knowledge, Analytical Target Cascading Based on Physical Programming (ATC-PP), solving the equilibrium point of coupled variables in noncooperative element, stability analysis of equilibrium point, the construction of approximation model on analysis module, et al. The above research system is well proved by a ship design optimization case study.Firstly, the theory system is constructed. The traits of complex system design space are analyzed carefully, and some important research nomenclatures are defined. And then, the outline of the proposed methodology is given.Secondly, the method based on two-layer mapping to explore design space is proposed. In this proposed two-layer mapping method, Rough Sets Theory (RST) is utilized to extract configuration rules from huge useful configuration data, for mapping from performance space to configuration space. Then, Self-orginzing Maps (SOM) is employed to eliminate useless design variables and cut variables intervals for mapping from configuration space to design space. This two-layer mapping method can mapping from performance space to design space, and realizes design space exploration and decreases design scopes.Thirdly, a new method named Analytical Target Cascading based on Physical Programming (ATC-PP) is proposed and its mathematical model and implement flows is researched. This method not only saves the merits of Analytical Target Cascading, decomposing the system based on components, but also utilized preference function to measure the errors of resposes and linking variables between father and son elements. Engineers'design habits and preferences are thoroughly present by preference function. In the preference intervals, the problems of equilibrium point with coupled variables and stability of equilibrium point in noncooperative element are studied. The equilibrium points are solved by rational reaction sets presented by response surfaces. And then, the Laypunov direct method in control theory is developed to analyze the stability of the decoupling in system, which can judge the strability of decoupling in ATC-PP.Fourthly, the construction method of B-Kriging model is proposed. Compared with other approximation models, Kriging model is more precise. In ATC-PP, in preference intervals, the means of design variables are unpredictived, as a consequence, a Kriging model (B-Kriging model) based on Bayesian Variable Selection Method is constructed, is introduced. And for deeper research, corcibly remain linking variables in B-Kriging model is proposed to avoid the linking variables deleting, which can make the whole system more feasible and stable.Fifthly, the proposed design space exploration and coordinated decomposition system is employed in conceptual ship designs stage. A 50000DWT Handymax Bulk Carrier is taken as a caes study to vertify the proposed theory system in this dissertation is useful and ideal.Finally, the conclusions deduced from this dissertation and prospects for future research will be suggested.