| Customer's demand change is inevitable in the process of complex mechanical product design,those changes may cause product design delay and increase design cost.When customers put forward changes in demand,how to respond quickly and make scientific decisions is a key factor for enterprises to enhance their market competitiveness.In this context,how to quantify the structure of complex mechanical products? How to dynamically describe the propagation process of customer's demand changes? How to scientifically evaluate the impact of customer's demand changes? How to achieve product configuration update and redesign in a fast and low-cost way? These are all the urgent issues that need to be solved for enterprises at present.Based on the complex network theory,this paper makes a deep study of complex mechanical product structure modeling and product reconfiguration in view of customer's demand change scenarios.The key issues in this paper include: the expression of complex mechanical product structure oriented to customer's demand change,the analysis of communication process of customer's demand change,the impact assessment of customer's demand change and the reconfiguration design of complex mechanical products.The main contents of this paper are described as follows:Firstly,in order to quantitatively express the structure of complex mechanical products,a modular network model of complex mechanical products is constructed for customer's demand changes in this paper.The main work of this section include: a)The relationship between different parts were expressed based on interval intuitionistic fuzzy sets from four aspects: functional correlation,physical structure correlation,customer participation and sustainability;On this basis,the related network model of the parts of complex mechanical products is constructed based on the complex network modeling theory,which be used to quantitative expression of the structure of complex mechanical products,here,the part as the network node,the relationship between parts as the network edge,the relevance strength as the network weight.b)In order to accurately divide the module of complex mechanical products,an improved GN algorithm is proposed to divide the module of complex mechanical products to construct the modular network model of complex mechanical products,the improved algorithm is mainly embodied in the combination of degree centrality and generalized median with classical GN algorithm.c)A 2.5WM wind turbine model and module division case be used to validate the research model and method in this chapter.Secondly,in order to dynamically describe the transmission process of customer's demand change in the modular network model of complex mechanical products,the dissemination model of customer's demand change was constructed based on the complex network propagation dynamics and scale-free network evolution mechanism.The main work of this section include: a)The nodes are divided into root node,leaf node and intermediate node according to the location of nodes in the network and the relationship with other nodes,then,the change propagation characteristics of different types of nodes was analyzed;b)Based on the evolution mechanism of scale-free network,combined with the structural and topological characteristics of modular network of complex mechanical products,the increase and deletion of network nodes,the growth and deletion of edges,the optimal connections between nodes caused by change propagation are analyzed.Then,combined with SI classical propagation model,the dissemination model of customer's demand change in complex mechanical product modular network is constructed.This model dynamically describes the process of upstream node change dissemination and downstream node change dissemination.In order to reveal the mechanism of change propagation,Calculate the change propagation rate and the ratio of changed nodes at each time to fully reflect the change propagation rate and range of different initial changed nodes;Calculate the strength of outgoing and inbound nodes to analyze the propagation types and cost of different nodes;Calculate the centrality of nodes to identify key components that affect change propagation;Taking a wind turbine design process as a case study,the effectiveness of the proposed method is verified.Thirdly,in order to accurately evaluate the impact of customer's demand change on complex mechanical product design and make scientific decision on customer change,a method of customer's demand change impact assessment is proposed based on global parameters of network.The main work of this section include: a)In order to improve the search efficiency of change propagation path,on the basis of transforming the two-way relationship of network nodes into one-way relationship,taking the initial change node as the benchmark,the hierarchy of nodes is divided according to the association relationship between nodes,then a feasible change propagation path search method is proposed based on node hierarchy division;b)In order to systematically evaluate the impact of customer demand change,a method of customer demand change impact assessment based on network global parameters is proposed,which evaluates the positive impact of customer's demand change(customer's satisfaction and product performance)and the negative impact of customer's demand change(transmission range of change,additional change cost and additional change time);on this basis,a method of customer's demand change impact assessment is proposed.Here,the decision-making strategies responding to customer's demand change requests include three main strategies and two auxiliary strategies: the main strategies including efficiency-first strategy,minimum change cost-first strategy,minimum change time-first strategy;the auxiliary strategies including uncoupled priority strategy and latest elimination priority strategy,which can assist enterprises to make scientific decisions for the customer's demand change;c)A wind turbine is taken as a case study to validate the research method in this chapter.The results show that the research method proposed in this paper is effective and can guide enterprises to make scientific decisions on customer's demand changes.Fourthly,in order to improve the design efficiency of product reconfiguration after accepting customer's change requests,the configuration updating methods for complex mechanical products with different parts types are proposed.The main work of this section include: a)On the basis of existing research results,a global general parts classification method is proposed based on global parameters of complex network,which divides parts into standard parts,general parts and customized parts.This method effectively takes into account the number and functional weight of parts used in product machinery product family,achieving more scientific parts classification.b)For configuration updating of general parts,a method of configuration updating for general parts of complex mechanical products is proposed based on rule reasoning and fuzzy similarity method,which combines configuration updating of general parts module and parameter adjustment of parts.For the configuration updating of customized parts,considering the quality loss of parts,the configuration updating model of customized parts is constructed from two aspects: the bigger the better and the smaller the better.The model is solved by using evolution algorithm with embedded orthogonal hybridization.The algorithm effectively solves the issue that 0-1 integer variables are difficult to integrate into the evolutionary process.c)The effectiveness of the research method in this chapter is verified by solving the configuration updating issue of a wind turbine driven with customer's demand change.The results show that the research method in this chapter effectively improves the efficiency of product configuration updating.In summary,the research results of this paper are devoted to improving the scientific and efficient decision-making when the enterprises response to customer's demand changes in the process of complex mechanical product design.At the same time,the research results of this paper are expected to enrich and expand the theoretical system of complex mechanical product design field. |
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