Under Fuzzy Environment, Safety Stock Research

With the trend of supply chain management, the competition between enterprises has been replaced by the competition between integral supply chains. In order to maintain high service level in SC, every node enterprise needs to hold some stocks. Safety stocks are used to buffer the uncertainties in SC and provide better customer service. SCM aims to minimize the safety stocks of enterprise without influencing customer service level. Thus, appropriate safety stocks are important to the success of supply chain.In this paper, we treated the problem of determining safety stocks with fuzzy theory. Considering demand and lead time are the two major sources of uncertainties, we use Gauss fuzzy number and triangular fuzzy number to describe them. Cycle service level (CSL) and fill rate (FR) are used to measure the service level. Continuous review and periodic review stock control policy are considered. The main contents can be concluded as follows:1) The credibility distribution function and expected value of Gauss fuzzy number are obtained according to credibility theory, which is the core theory in this paper.2) For stock points, the safety stocks strategies are expanded from stochastic environment to fuzzy environment based on former research. We formulate the safety stock strategies with fuzzy demand, fuzzy lead time and fuzzy demand and lead time under continuous review and periodic review control policy, respectively. For the situation with one fuzzy variable, we develop the model based on credibility theory and solve it with MATLAB software; for the situation with two fuzzy variables, we introduce fuzzy pessimistic value and solve the problem via fuzzy simulation. Meanwhile, some helpful qualitative conclusions are obtained through analyzing the numeric example.3) The safety stock strategies are expanded from stock points to coordinated supply chain. The serial structure, divergent structure and convergent structure are mainly considered. The safety stock strategies of these three special supply chains are studied.