Research On Technologies Of Multi Performance Fusion Layout Design For Complex Product Scheme Design

Scheme design is an important step during the complex product design process, the technologies of multi performance fusioned layout design for complex product scheme design is put forward and studied based on the overview of the state of art of the technology. The technologies and methodologies including structural layout modeling, the process requirements conversion methodology, coupled identification of accuracy characteristic importance, accuracy trade-off allocation, structural layout combination technology and product scheme evaluation methodology are deeply studied.The organization of the whole thesis is as follows:In Chapter1, the reviews of product scheme deisgn is given. The shortage of present research for product scheme design is proposed. Then the research content and architecture of the dissertation is presented.In Chapter2, a general layout modeling technology for product structure performance is discussed. A novel approach based on a hierarchical product layout element relationship net and a product layout polychromatic model is presented at the aim of solving a mapping problem between product principle schemes and structural layout schemes. The hierarchical product layout element relationship net is constructed on the basis of layout modules and property relationship net; then the product layout polychromatic model and its reasoning algorithm are proposed under the mathematical representation of the hierarchical product layout element relationship net in polychromatic sets element pigmentation and unified color. Subsequently, the mapping process among product functions, movements and layout modules is formally described utilizing polychromatic sets boolean matrix reasoning rules. This representation is convenient for the storage, the management of the product structural layout design information and the subsequent design work, also supports product layout axiomatic design efficiently.In Chapter3, requirements conversion method and accuracy characteristics identification technology are discussed. An analysis on multi factors and uncertainty in the manufacturing equipment planning process is provided. A quality house Analytic Network Process (ANP) model is constructed to describe the coupling relationships and give the conversion method among the factors, such as customer performance requirement, customer process requirement and product engineering characteristics. Meanwhile, motivated by the coupling relationship between the product accuracy variation process and parts cutting process, an identification method is developed, which address key accuracy characteristics of complex product for parts machinability evaluation. Parts machinability Hidden Markov Model(HMM) is constructed via regarding the accuracy variation process and cutting process as a coupling system. Additionally, parts machinability evaluation model and identification method are formulated, proposed to get the optimal cutting characteristic state for coupling system. Therefore, the manufacturing performance coupling mapping for product general layout design is realized.In Chapter4, product motion accuracy scheme design method is discussed, and investigation of motion error analysis, volumetric error model for transmission system and accuracy allocation method for complex product during the early design stage are given. For this purpose, a transmission system volumetric error model, which is based on motion error matrix and screw theory, has been derived for mapping transmission components error parameters to the volumetric error of the machine tool. The volumetric error matrix combines motion errors along the machine tool kinematic chains. Subsequently, the volumetric error model is regarded as a volumetric error twist, which is formulated from the volumetric error matrix. Additionally, the transmission system volumetric error twist model has been used as design criteria for accuracy optimal allocation, with constraints on twist magnitude and design variable limits. Then, design optimization has been performed by using a multi objective nonlinear optimization technique to minimize the manufacturing cost and magnitude of volumetric error twist pitch. To solve this multiple objectives programming problem, this study proposes an approach integrating lagrange multiplier and gradient descent operator with Non-dominated Sorting Genetic Algorithm (NSGA-Ⅱ) and VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR). Modified NSGA-Ⅱ searches for an allocation scheme Pareto optimal front. VIKOR determines the best compromise solution from the Pareto set. Consequently, motion accuracy trade-off allocation is realized.In Chapter5, to meet requirements of intelligent design of product layout, a novel approach is put forward on the basis of analyzing product structure layout constraints. The methodology is defined as a fusion model constructed through a position graph and a performance model. The performance model is a mapping among product function requirements model, movement allocation model and simplified module structure; the product topological layout structure is described by a lower body array. A position graph is used to illustrate the relation as location, order and adjacency of product module spatial layout structure, and also to assemble the layout structure. Meanwhile, investigates multi performance evaluation indexes weight uncertainty and trade-off evaluation problem, and proposes a novel product scheme selection method, which is based on a conjoint analysis, variable weight and VIKOR method, to meet an evaluating criteria importance uncertainty and a trade-off evaluation problem at a complex product scheme design decision making stage. The trade-off selection method is developed to solve the function and cost balancing decision making, and product scheme design flexible evaluation is realized.In Chapter6, the application of the theories and method of numerical control (NC) machine tools structural layout modeling and layout design is studied. The case study has been proved the validity and feasibility of the proposed methods in this dissertation.In Chapter7, the summary for dissertation and the future research work prospects are given.