Research On Reliability Allocation Method Of Mechanical System In Conceptual Design Stage

Reliability is one of the most important quality index, the basic guarantee ofproduct technical and economic performance. It determines the competitiveness ofproducts in the market. Reliability allocation is an engineering decision process ofbalancing and optimization, related to the manpower and resources deployment.Aiming at the reliability distribution method used in conceptual design phase ofcomplex mechanical system, this paper reviewed the theory of reliability andreliability allocation. Improvements were made on some key issues. Maincharacteristics of the mechanical system reliability allocation were summarized.Making full use of fuzzy information in the early design, AHP and generalized costfunction were improved to get higher applicability and accuracy considering thecharacteristics of the interaction between subsystems and the system itself.Improved fuzzy AHP used a new method to get judgment matrix, interactionsbetween subsystems relationship were considered during the reliability allocationEvaluation results were obtained by fuzzy weighted average method. FAHP can makebetter use of the human brain to make right judgments against blurring, the role ofexperts is given full play, it has a relatively wide range of application value andpractical significance. Based on a comprehensive analysis of the generalized costfunction, a new function is proposed. This function meets six criteria for generalizedcost function. Two parameters of feasible and importance degree are introduced. Wegot feasible degree by considering the criteria of reliability allocation, and importancedegree by considering RPN. This method combines reliability allocation principlesand practical reliability allocation constraintsThe feasibility of the two methods were verified by examples, although the maindiscussion on reliability allocation problem is of series system, method of parallelsystem is also put forward, the hybrid system can be changed into series and parallelsystems through appropriate deformation.