Allocating redundancy,maintenance and spare parts for minimizing system cost under decentralized repairs

Reliability-redundancy allocation,preventive maintenance,and spare parts logistics are crucial for achieving system reliability and availability goal.Existing methods often concentrate on specific scopes of the system’s lifetime.This paper proposes a joint redundancymaintenance-inventory allocation model that simultaneously optimizes redundant component,replacement time,spares stocking,and repair capacity.Under reliability and availability criteria,our objective is to minimize the system’s lifetime cost,including design,manufacturing,and operational phases.We develop a unified system availability model based on ten performance drivers,serving as the foundation for the establishment of the lifetimebased resource allocation model.Superimposed renewal theory is employed to estimate spare part demand from proactive and corrective replacements.A bisection algorithm,enhanced by neighborhood exploration,solves the complex mixed-integer,nonlinear optimization problem.The numerical experiments show that component redundancy is preferred and necessary if one of the following situations occurs:extremely high system availability is required,the fleet size is small,the system reliability is immature,the inventory holding is too costly,or the handson replacement time is prolonged.The joint allocation model also reveals that there exists no monotonic relation between spares stocking level and system availability.

Bridging reliability and operations management for superior system availability:Challenges and opportunities

Recently,firms have begun to handle the design,manufacturing,and maintenance of capital goods through a consolidated mechanism called the integrated product-service system.This new paradigm enables firms to deliver high-reliability products while lowering the ownership cost.Hence,holistic optimization models must be proposed for jointly allocating reliability,maintenance,and spare parts inventory across the entire value chain.In the existing literature,these decisions are often made fragmentally,thus resulting in local optimality.This study reviews the extant works pertaining to reliability-redundancy allocation,preventative maintenance,and spare parts logistics models.We discuss the challenges and opportunities of consolidating these decisions under an integrated reliability-maintenance-inventory framework for attaining superior system availability.Specific interest is focused on the new product introduction phase in which firms face a variety of uncertainties,including installed base,usage,reliability,and trade policy.The goal is to call for tackling the integrated reliability-maintenance-inventory allocation model under a nonstationary operating condition.Finally,we place the integrated allocation model in the semiconductor equipment industry and show how the firm deploys reliability initiatives and after-sale support logistics to ensure the fleet uptime for its global customers.