Location Inventory Problem Of Service Parts Based On The Life Cycle

Service spare part plays an important role of the after-sales service. Damaged parts need to be replaced, which produce spare parts requirements, in the field of construction machinery, equipment manufacturing, aerospace, medical and other industries.The manufacturer of the equipment in order to achieve sales service commitment, often need to reserve a certain number of spare parts to meet customer needs.However, service parts, with the feature of low demand, distributed randomly, and a wide variety of characteristics, need management methods to support this system, different from the general merchandise management.The one hand, the effective management of the service part is able to serve the manufacturing industry, support to our country from the manufacturing country to manufacture power forward. On the other hand, service part is also becoming one of the main sources of profits for producers. In this process, how to save the service parts, for example,"which storage","what storage","how many storage" has been needed urgently to solve the problem of enterprise service management.Based on this background, service parts location invenroty problem decision based on the life cycle of the service parts was analyzed. Service parts life cycle was defined theoretically, and can be divided into the production phase and stop production period. Then, system dynamics principle of service parts was researched on, a system dynamics model was established, and the service parts location inventory risk was anlyzed.On this basis, respectively, from the production period and stop production period, service parts location inventory model was established, and a heuristic algorithm was adopted to solve the problem.Specifically, the paper mainly completed the following works:1. Service parts life cycle was defined theoretically. The length of service parts life cycle should be divided production period and off production period, through comparison service parts life cycle and general product life cycle. Three main indicators to characterize the service parts life cycle was proposed, which include rvice parts demand function, the service spares profit function, the system profit function, constituted by the manufacturing&sales system and service parts logistics system. Then matahematical models, to describe the indicators, were established. At last, the service parts life cycle curve shape was described by the numerical simulation. Through the simulation, the system profit is zero as the optimal stop-production point. 2.The system dynamics of service parts were analyzed. Then, two system dynamics models were established, whether considering the factor of lateral transshipment or not, which complished reality analysis and theoretical abstraction. The dynamics model without considering lateral transshipment is constituted of a central warehouse and a local warehouse, while the dynamics model considering lateral transshipment is composed of a central warehouse and two local warehouses. Through setting produt sales change to simulate product life cycle over time, it is concluded that different characteristics on service parts inventory were displayed on the production period and off production period, and service parts invenroy risk more greatly. So the location inventory problems should also be researched on the two stages, production period and off production period.3. Service parts location inventory problem on production period was researched on. The problem is limited to a single service spare part. With constrains of inventory capacity and service level, minimum cost objective functions based on lateral transshipment were established, whether to consider the distribution problem. Then, heuristic algorithm combined of implicit enumeration method and the genetic algorithm was designed. Trough the simulation example, feasibility of the method and the advanced of the model were verified. Through the research, the following problem can be solved:(1).local warehouse amount and locations under the condition of central warehouse determined;(2) the optimal inventory decision for selected service parts local warehouse;(3) reasonable arrangements for vehicles circuitous and distribution lines.4. Service parts location inventory problem off production period was researched on. Three service parts storage modes were analyzed, which include:the main local warehouse&general local warehouse mode, single inventory system mode, and two inventory system mode. Above the three modes, the main local warehouse&general local warehouse mode was regarded as the basic mode, and other two modes as special modes. And location inventory mode for a basic mode was established, and two special modes were discussed. Then iterative algorithm based on genetic algorithm was adopted to solve the problem. Through the simulation example, the feasibility and effectiveness of the mode and the method were verified. Through the research, the following problem can be solved:(1).the storage mode choice off production;(2)the choice strategy and inventory strategy for local warehouse off production.