Research And Application On Key Technologies Of Change Management In Complex Mechanical Product Design

Complex mechanical products are the important products of equipment manufacturing industry.Their design capacity is an important manifestation of the level of equipment manufacturing industry.In complex mechanical product design,high customization,long design cycles,and high technology integration of complex mechanical products make that changes occur frequently,and and result in the design cycle significantly lengthened and design costs obviously increased.When design changes occur,increasing the agility and accuracy of change responses can significantly reduce the impact of changes on product design cycles and costs.Scientific change management is important for improving the agility and accuracy of change responses.Nevertheless,the research on change management in complex mechanical design is still at the exploratory stage.Meanwhile,there are some problems in the research,such as incomplete assessment of change impact on product structure,low efficiency of configuration change and low accuracy of forecasting design task change time.In this case,there is an urgent issue to be addressed,which are about the change management in complex mechanical product design,to improve the agility and accuracy of change responses.According to the above analysis,this dissertation has conducted in-depth research on the key technologies of the change management in complex mechanical product design,which is about the assessment of the overall change impact on complex mechanical product' structure,the optimization for configuration changes and the prediction of design task change time in complex mechanical product design.The main research contents of the dissertation are as follows:Firstly,the dissertation puts forward an assessment model of the overall change impact on complex mechanical product' structure for making scientific change decisions.The model contains the following steps need to be executed in sequence: the assessment of change propagation probability,the assessment of propagation impact probability,and the assessment of the overall change impacts.Moreover,this dissertation respectively comes up with a method for assessing the probabilities of change propagates to upstream parameters based on the grey relationship strength between the design parameters and an assessment method of propagation impact probability based on the analysis of design parameters changes,thereby objectively assessing both the propagation probability and propagation impact probability of design change.For the sake of accurately assessing the change impacts on the whole structure of complex mechanical product and this dissertation proposes an assessment method of the overall change impacts based on the hierarchy of design parameters.Secondly,the dynamic optimization method for configuration change in complex mechanical product design is proposed for minimizing the price of configuration change and improving the efficiency of configuration change.The configuration change process of complex mechanical products is analyzed to reveal the effect mechanism of change on the upstream and downstream parameters,and then an assessment method of change price on the upstream and downstream parameters is proposed based on this mechanism.In addition,in order to minimize the cost of changing the upstream and downstream parameters,the dynamic optimization method of configuration changes in complex mechanical product design,which is integrated by dynamic optimization for upstream change parameters and the dynamic search of downstream change parameters,is put forward.Thirdly,the intelligent method for forecasting design task change time of complex mechanical product is proposed to improving the prediction accuracy.First,an intelligent evaluation model of design agents' knowledge ability based on multivariate time series and fuzzy v-support vector machine is put forward in order to exactly evaluate the design agents' knowledge ability and to lay the foundation of predicting design task change time.The evaluation model takes the multiple relations,dynamics and ambiguity of design agents' knowledge ability into account.Then,an intelligent prediction model of design task change time based on multivariate fuzzy weighted v-support vector machine is proposed for the sake of accurately predicting design task change time.The prediction model considers the impact of design agent ability and design task characteristics on design task change time,ambiguity of design agent abilicy and similarity between design tasks.Next,an adaptive genetic algorithm is designed to optimize the parameters in the evaluation model and prediction model.Fourthly,this dissertation takes the change management of plunger pump fuel injection system designed by company H as a case study to verify the validity and feasibility of the proposed methods and models.Meanwhile,this dissertation verifies the superiority of the proposed methods through the comparative analysis with the existing research.At last,this dissertation refines the research results and innovations,and discusses future research directions.