Research On Renewing Warranty Strategy And Its Maintenance Optimization Formulti-component Products

With the increasingly fierce market competition and consumers' demand for products,providing only minimal repair service within the warranty period cannot meet the consumers' needs anymore.Free replacement renewing warranty strategy requires that manufacturers freely replace the failed product during the warranty period with a new product,and recalculates the warranty period.The free replacement renewing warranty strategy,which is favored by the consumers,has become an important means for manufacturers to win the market and improve customer satisfaction.At present,the theoretical research and engineering application related to renewing warranty are not perfect and mature enough;manufacturers urgently need the theoretical guidance to implement the renewing warranty strategy.From the manufacturer's perspective,and aiming to reduce the renewing warranty cost,this thesis integrates the warranty deadline and the threshold of maintenance times into the renewing warranty strategy,and three kinds of novel combined renewing warranty strategies are proposed.The major work in the thesis is as follows:(1)A two-stage optimization model for renewing warranty considering warranty deadline is proposed.In the first stage of the product after sales,a renewing warranty with deadline(RWD)policy is implemented.And the replacement warranty with limited repair times(RWLRT)policy is applied in the second stage.Under the free replacement and pro-rata warranty policy,the corresponding two-stage cost optimization model is established to minimize the cost rate and obtain the optimal warranty period from the manufacturer's perspective.The case study shows that manufacturers can effectively reduce the warranty cost rate by implementing the RWD strategy.(2)A two-stage renewing warranty policy with the threshold of maintenance times is proposed.Based on the ratio,we divide the warranty period into two stages,i.e.renewing warranty stage and minimal repair warranty stage.In the first stage,when the number of minimal repairs exceeds the given threshold,the failed item will be replaced by a new one with a new warranty period.In the second stage,only minimal maintenance is used to remove the failure,and periodic preventive maintenance is carried out to slow down the degradation of product performance.On this basis,non-homogeneous Poisson process and geometric process are used to establish the model of renewal's number.By improving the price function model,profit models under four schemes are established.The numerical example analysis is completed.The results show that it can help manufacturers reduce the warranty cost and increase the expected profit of products by considering the threshold of maintenance times.(3)A two-level threshold renewing warranty and its cost are studied for multi-component products.Taking the multi-component product as the research object,a two-level renewing warranty strategy based on component-level threshold and product-level threshold is proposed.The failure dependence probability matrix is used to describe the failure correlation among components,and the warranty cost models of multi-component product with or without correlation are established respectively.Through comparative analysis of different schemes,compared with the one-level renewing warranty strategy which only considers the component level threshold,it is found that the two-level threshold renewing warranty strategy can effectively reduce the warranty cost and release the cost pressure for manufacturers.In addition,failure dependence will lead to a significant increase in the warranty cost for multi-component products.The main contributions of this thesis are as follows:(1)Based on the warranty deadline and threshold of maintenance times,three types of novel combined renewing warranty strategies are designed respectively;(2)The research object extends from single component product to multi-component product,which provides a new perspective and scientific theoretical basis for manufacturers to implement the combined renewing warranty strategy.