不完全维修的二维产品保证成本

以不完全维修的故障强度下降因子与时间域为待优化变量,建立不完全维修的二维产品保证成本模型。首先通过确定最优的故障强度下降因子,再采用两阶段处理方法对不完全维修时间域进行优化,以实现最小产品保证成本。最后对模型进行数据分析后可知:随着产品使用率的提高,不完全维修策略比最小维修策略的二维产品保证成本更低。     

基于混合故障率的设备分阶段顺序维修决策优化研究

针对传统顺序维修策略在实际中操作性困难的问题,提出设备的分阶段顺序维修模型。为了使顺序维修策略在实际中更具有操作性,将设备的维修过程分成3个阶段,每个阶段的维修间隔都是相等的,经过3个阶段的维修后,对设备进行预防性更换。利用役龄改善因子和故障率递增因子的混合故障率函数描述设备的退化过程,考虑在维护期内突发性故障成本、预防性维修成本、更换成本和停机损失成本,设备的可靠度不低于一定水平的情况下,以在维护期内总维修费用率最小为优化目标,建立设备分阶段顺序性维护模型,利用非线性约束优化工具求解3个阶段的维修间隔和维修次数。通过实例分析可知,该维修策略可以节约15%左右的维修费用,验证模型的有效性。     

液压千斤顶的维修与保养

液压千斤顶作为煤矿生产中的常用设备,对于保证煤矿生产安全性,提升煤矿生产的可持续性有着非常重要的作用。同时,液压千斤顶也是煤矿容易出现故障的机械类型之一,全面做好液压千斤顶的维修与保养工作较为关键。该文从液压千斤顶的常见故障及原因分析入手,研究了液压千斤顶故障维修策略,并针对性地提出了提升液压千斤顶维修和保养水平的相关策略。     

考虑预防维修时间及相关性的多部件系统维护策略

针对动车组关键系统维修过程中涉及部件数量多、维修时间长、维修费用高的特点，提出了预防维修时间、故障相关性、经济相关性3重因素影响下的多部件系统机会维护策略。首先对多部件建立部件故障率模型。在此基础上，考虑预防维修时间，将部件层预防维修成本分为独立时间成本和依赖时间成本，对经济相关性进行建模，再以系统维修费用率最小为优化目标建立系统层维护模型，并应用遗传算法求解。最后通过算例表明，相较于考虑单一因素的维修策略，所提维修策略可降低系统维修成本10%及以上，验证了考虑维修时间和部件联合相关性的必要性和有效性。     

面向二维保证的产品大修策略制定

为更有效地制定制造商在二维保证政策下的维修策略,针对以往面向产品保证的维修策略研究中,忽略顾客满意度对制造商成本产生的影响这一缺点,将顾客满意度下降对制造商造成的隐性损失考虑在内,分别构建最小维修策略和大修策略下的制造商期望总成本分析模型。以汽车产品安全气囊系统中的传感器部件为例,利用两阶段过程方法,求解获得使制造商在二维保证政策下期望总成本最小的大修策略。研究结果表明,与最小维修策略相比,大修策略使制造商的期望总成本降低了22%,顾客满意度上升到61%,为制造商制定二维保证政策下的维修策略提供了有效的决策支持。     

基于寿命周期成本分析的产品延伸保修决策优化模型

随着用户对产品寿命周期成本的日益重视,延伸保修已成为生产商新的关注点。延伸保修对产品维修使用费用以及市场竞争力有很大影响,为得到产品延伸保修决策优化方案以降低寿命周期成本,在考虑预防性维修策略的基础上,分析了生产商延伸保修定价策略,构建出一种以用户在产品使用寿命期内单位时间总维修成本最小为目标的延伸保修决策优化模型,并提出了求解模型的网格搜索(grid search)算法。通过引入算例,借助Matlab仿真软件实现网格搜索算法,在保证生产商利益的基础上,有效的降低了产品单位时间总维修成本,延长了产品使用寿命周期长度,由此得到了用户最优延伸保修决策方案,验证了模型和算法的合理性和有效性。     

具有多种约束的两工作等级综合维修策略

为了制定设备多工作等级维修计划,提出了一种综合维修策略。采用综合维修策略,基于维修效果模型和损伤累积理论,在多种约束条件下,建立了两工作等级设备全寿命周期收益模型。引入数字算例,验证了该策略可以实现设备全寿命周期收益的最大化。     

基于PDCA循环法降低转向架流水线电气故障率的研究

运用PDCA循环法,对转向架流水线电气故障发生的现状进行调查分析,发现DP(PROFIBUS-DP,现场总线)通信故障是发生次数最多的电气故障,运用鱼骨图法分析故障原因,找出关键原因,制定改进计划,经过一段时间的实践后检查实施效果,PDCA循环法的应用确实降低了转向架流水线电气故障率,减少了维修费用和缩短了维修时间,提高了转向架流水线作业效率。PDCA循环法的成功应用为类似的设备故障处理提供了思路,可推广应用到全国货车车辆段使用。     

考虑役龄的预防性维修计划与缓冲区库存联合优化决策

针对生产系统中的预防性维修问题,提出考虑缓冲区库存和役龄回退的预防性维修策略,分析役龄对故障率的影响,推算出设备的故障次数,建立设备预防维修计划与缓冲区库存联合优化决策模型。该模型以预防性维修周期T和缓冲区库存量S为决策变量,以周期内单位时间总费用CT(T,S)为决策目标,并运用离散迭代算法进行算例仿真求解,获得最佳的缓冲区库存量及最优预防性维修周期,使单位时间总费用达到最低。算例对比分析证明了策略模型能有效节省生产成本。最后通过灵敏度分析得出相关参数对于策略模型的影响,验证模型的有效性,为维修计划提供理论指导。     

考虑制造商设备维修的制造—零售供应链决策与协调

设备可靠性是影响供应不确定的重要因素。为了研究企业内部的维修策略对整条供应链的运营策略产生的具体影响，在考虑设备维修的情况下，针对单个制造商和单个零售商构成的二级供应链，运用Stackelberg博弈的方法研究制造商的最优维修策略和定价策略以及零售商的最优订货量。研究结果表明，制造商的预防性维修次数存在上限且最大维修次数与设备可靠性无关；预防性维修策略有助于提高制造商的产量，降低产品的批发价格，但制造商的最优产出量不会达到企业的最大产能；收益共享契约能够实现供应链的协调；制造商在任何情形下都具有提高设备可靠性的动机，但零售商只会在市场规模较大时才存在为制造商提供设备改造资金的动机。     

A two-dimensional preventive maintenance strategy for items sold with warranty

Conventional preventive maintenance (PM) strategies under two-dimensional (2D) warranties are usually age-based or usage-based, which means that the implementation of PM activities is based solely on item age or usage. In this paper, a new PM strategy, called 2D PM strategy, is proposed for items sold with a 2D warranty. Under this strategy, the item is preventively maintained every K units of age or L units of usage, whichever occurs first. The marginal approach is used to describe the effect of age and usage on item reliability by treating usage as a random function of age. Besides, the effect of PM is characterised by the reduction of virtual age. The objective of this study is to identify the optimal 2D PM strategy under fixed warranty terms so as to minimise the total expected warranty servicing cost from the manufacturer’s perspective. A numerical example is provided to demonstrate the effectiveness of the proposed PM strategy. It is shown that the 2D PM strategy contains the age-based and usage-based strategies as special cases, and outperforms them in terms of warranty servicing cost. Finally, how to implement the proposed PM strategy in practice is discussed with an illustrative case.     

Designing and pricing of two-dimensional extended warranty contracts based on usage rate

For vehicles sold under a two-dimensional warranty, which consists of two-dimensional region of age and usage, automobile manufacturers or third-party after-sales departments offer free warranty service under the base warranty. Consumers require a longer and better developed warranty service because of the rapidly developing production technology and other reasons. In the topic of two-dimensional warranty, previous research has extended the coverage of the base warranty, which satisfies consumers’ requirements but places significant pressure on automobile manufacturers. This study proposes a designing and pricing model of two-dimensional extended warranty contracts. The mathematical model is divided into two categories: the purchase of two-dimensional extended warranty service at the point of sale and the expiration of the base warranty. Based on the maintenance strategy used during the extended warranty, we classify this study under the minimal repair and combined maintenance strategy models. With the use of the failure and usage rate distribution functions, the mathematical pricing models of each sub-case are presented. A numerical example of a vehicle made in China is given to illustrate the procedure of the models. The results of this study provide automobile manufacturers with guidelines on designing and pricing two-dimensional extended warranty contracts.     

A maintenance strategy for two-dimensional extended warranty based on dynamic usage rate

Maintenance strategies are commonly used for repairable products or items to reduce the warranty cost in the warranty coverage. This study proposes a new warranty maintenance strategy for two-dimensional extended warranty (EW) based on dynamic usage rate. Unlike previous studies that assumed a constant usage rate, the present study regards the consumer usage rate as dynamic in the two-dimensional EW coverage. A maintenance model is constructed to determine the optimal maintenance degree of warranty claim points and help service providers accurately estimate and reduce warranty cost. A numerical example of an automobile made in China is discussed to demonstrate the effectiveness of the proposed model. The formulated model can effectively reflect the changes in the consumer usage rate and thus helps service providers develop an accurate maintenance strategy. Meanwhile, the developed model can better reduce warranty cost compared with maintenance strategies with minimal repair.     

Optimal burn-in strategy for two-dimensional warranted products considering preventive maintenance

Burn-in and preventive maintenance (PM) are effective approaches to reduce the number of warranty claims and warranty cost during post-sale support. With harsher burn-in settings, early product defects can be removed, but at the same time product degradation is accelerated and more wear-out failures may be introduced. PM actions within warranty alleviate these negative effects. This paper proposes an optimal burn-in strategy for repairable products sold with a two-dimensional base warranty (BW) and an optional extended warranty (EW). Both performance-based and cost-based models incorporating PMs are developed to obtain optimal burn-in settings, including the burn-in duration and the burn-in usage rate, so as to minimise the expected number of warranty claims and total cost respectively. The impacts of different accelerated coefficients and PM degrees on the optimal burn-in strategy are analysed. In view of the performance and cost structures, we conduct numerical examples to illustrate the applicability of the proposed models. Practical implications from a sensitivity analysis for key parameters are also elaborated.     

考虑顾客不同使用强度的产品质保期和价格最优设计

站在制造商的角度进行一维质保期及产品价格策略的最优设计。考虑顾客不同使用强度对现场可靠性的影响,分别构建产品的失效率模型及最小维修策略时的质保成本模型。以期望利润最大化为目标,对最优的一维质保期和价格策略进行设计。最后,以某中央空调制造商作为算例,对中央空调的最优一维质保期和产品售价进行优化,并对主要参数进行敏感性分析。研究发现,特别是针对具有顾客不同使用强度的大型装置或系统,通过最优的质保期和价格策略设计可以有效地提升产品的利润期望值。     

保修计划中的成本与最优保修期研究

首先讨论了保修策略的各种类型,在此基础上建立了一种保修成本模型,最后,对保修策略中最优保修期问题进行了分析,给出了在不同产品故障分布情况下最优保修期的计算方法。     

A repair-replace strategy based on usage rate for items sold with a two-dimensional warranty

When a repairable item fails under warranty, the manufacturer has the option of either repairing the failed item or replacing it with a new one. In this paper, a repair-replace strategy is discussed for the manufacturer of a product sold with a two-dimensional warranty. The strategy is based on a specified region of the warranty defined in terms of age and usage with the first failure in the region rectified by replacement and all other failures being minimally repaired. An accelerated failure time (AFT) model is used to allow for the effect of usage rate on item degradation.     

Optimal reliability, warranty and price for new products

The success of a new product depends on both engineering decisions (product reliability) and marketing decisions (price, warranty). A higher reliability results in a higher manufacturing cost and higher sale price. Consumers are willing to pay a higher price only if they can be assured about product reliability. Product warranty is one such tool to signal reliability with a longer warranty period indicating better reliability. Better warranty terms result in increased sales and also higher expected warranty servicing costs. Warranty costs are reduced by improvements in product reliability. Learning effects result in the unit manufacturing cost decreasing with total sales volume and this in turn impacts on the sale price. As such, reliability, price and warranty decisions need to be considered jointly. The paper develops a model to determine the optimal product reliability, price and warranty strategy that achieve the biggest total integrated profit for a general repairable product sold under a free replacement-repair warranty strategy in a market and looks at two scenarios for the pricing and warranty of the product. The model assumes that the sale rate increases as the warranty period increases and decreases as the price increases. The maximum principle method is used to obtain optimal solutions for dynamic price and warranty situations. Finally, numerical examples are given to illustrate the proposed model.     

基于成本/效益分析的产品保证策略

从成本／效益角度对产品售后保证策略问题进行研究,对产品保证的特征和保证策略类型进行论述,探讨了产品保证策略的形成过程,最后运用产品保证策略成本模型对我国彩电产品保证策略优化处理。     

保固管理在项目开发上的应用

提出了不同的保固管理元素与运作架构,以期有效地整合项目开发流程与执行保固管理。在所描述的运作模式基础上,异于过去学者所发表的循序性作业流程,以螺旋式的运作流程来执行保固管理元素,由内而外来代表各项目开发的阶段,而以不同相位表示保固管理元素,透过这一新保固管理的运作架构,强调不论在项目开发任何阶段,都应适时考量到各保固管理元素,以确保后续产品服务品质,大幅提升产品可靠度20％以上,有效降低保固成本。