Research On Forming Mechanism And Application Of Hardware Product Design Defect

With the increasing competition in the market in recent years,enterprises tend to shorten the product development cycle to meet customer requirement quickly.Meanwhile,facing the trend of diversification and personalized for customer demand,today's products are becoming more and more complex.Those problems,such as product complexity,the shortening of the development cycle and the application of new technology,are all increasing the risk of design defects.Product design defects may not only degrade the quality of products,but also overrun budgets,extend schedules,and even jeopardize the success of product development.Design defects are formed in the product design process.Therefore,it is crucial to understand the formation mechanism of product design defects so as to effectively prevent and control design defects during the products design and development process.This paper focuses on the relationship among design defects,design processes and design activities.The formation mechanism of design defects,analysis of defect propagation,design defect assessment and defect control are studied based on Quality engineering theory,Network theory and System engineering.The main contents are as follows:Firstly,the relationship between design defects and design processes is studied.The design process structure consisting of the design processes,design sub-processes,design child processes and design activities is constructed based on the Work breakdown structure(WBS).Design defect influencing factors are from six design process elements,including input,output,resource,environment,functional design activities,and control design activities.Then the structural relationship model among design defects,defect influence factors and design processes which described four types of design defect formation mechanism is constructed.Moreover,the Polychromatic Set theory is further applied to construct the mathematical relationship between design defects and defect factors.Further,Interval Analytic Hierarchy Process is applied to analyze the relative importance of design defect influencing factors.Secondly,by analyzing the impact relationships of design activities on design defects,design activities is divided into three types: functional design activities,control design activities and auxiliary design activities.Functional design activities produce design defects.However,control design activities identify design defects.The identified design defects are then removed by functional activities.Auxiliary design activities neither produce design defects nor identify design defects.Thirdly,the formation of design defects is studied.The potential design defects in a single design activity are explored from the viewpoint of six process elements.Defect propagations are then analyzed from the time sequence relations between design activities which include independent,concurrent,series,coupling and condition.A directed weighted propagation network model for design defect propagation is established based on the input-output parameters relationship of design activities.The design defect formation mechanism is illustrated by analyzing the formation of potential design defect in the activities and the defect propagation between activities.Fourthly,a design defect assessment model is constructed.From the perspective of the design activities,an assessment model of defect is constructed using design activities as Bayesian network nodes based on the study of the design defect formation mechanism.The assessment model includes two aspects: defect assessment of design activities,defect propagation assessment between design activities.Using defect assessment model,design defect occurrence probability is calculated to identify the key design activities.Finally,the above theoretical research results are applied to engineering practice.The design defect identified method using the process element is successfully applied to identify design defect of aircraft assembly process,guiding the company to optimize the relevant process design.In addition,a case study involving the design of the crane boom shows the effectiveness and feasibility of the proposed defect assessment method.Further,based on research on forming mechanism and application of design defect,the management process framework of design defect including identification,prevention and control is presented.This paper systematically and comprehensively discusses these problems including the design defect formation mechanism,the design defect influencing factors and defect assessment,respectively.The research results not only enrich existing design defect identification and evaluation method,but also serve as a guide for hardware product defects prevention and control.