عنوان مقاله [English]
In a supply chain, the variability of orders can be more than the variability of demand, and this phenomenon is known as the bullwhip effect. Managers of supply chains have experienced this phenomenon in their orders and
inventory levels. Variability in orders or inventories in supply chains is generally thought to be caused by exogenous random factors such as uncertainties in customer demand or lead time. According to performed studies that have been done in this area, however, orders or inventories may exhibit significant variability, even if customer demand and lead time are deterministic. On the other hand, the decrease of order variability, due to an increase in inventory variance, has a negative effect on the level of customer service. Due to this weighty matter, in this paper, we show that how this variability; dynamism, may occur in a four-level supply chain (A retailer, a wholesaler, a distributor and a manufacturer) as total cost and bullwhip effect, and offer insights into how to manage relevant supply chain factors to eliminate or reduce system dynamics. The supply chain is characterized by the classical beer distribution model with some modifications, including changes in demand, information and ordering policy. In this model, we observe the supply chain dynamics under the influence of various factors: demand pattern, ordering policy, demand-information sharing, and lead time. The effects of these factors on the chain dynamics using factorial design show that the ordering policy factor is considered the most in chain dynamics, while information sharing and lead time factors are not, respectively, effective on total cost and bullwhip effect. Therefore, the factors, information sharing at high level for decrease in bullwhip effect, and lead time at low level for decrease of total cost, are considered constantly. Thus, according to the type of demand pattern, chain dynamics can be reduced with laying to a selection of ordering policy type.