چكيده به لاتين
Abstract
In this research, a novel mathematical model is proposed to optimize the upgrade level, and implement the multi-level sequential imperfect preventive maintenance (PM) and replacement for second-hand repairable mechanical system that was sold under warranty. The product is assumed to deteriorate by ageing. The focus of the PM's implementation is to increase the reliability and availability levels of the equipment during the warranty period in order to satisfy and encourage more customers to purchase second-hand equipment. Optimization of the problem is carried out in two steps. At first, based on the reliability-availability criteria, the optimum times for executing the PMs are selected. In the second step, based on the cost criteria, the optimal level of repair for each scenario and the optimal PM intervals are determined in which the total costs of the system is minimal. In addition to the mentioned modeling of the problem, an improved hybrid hazard rate model is proposed in this research. The developed model takes into account the conditions for the slope of failure function and the level of age improvement of the equipment under each scenario to be dynamically determined by the model. In order to illustrate our proposed model, we present and discuss some numerical examples and a sensitivity analysis is performed on the optimality of the maintenance schedule based on the model parameters.
Key words
Sequential imperfect preventive maintenance, warranty, remanufacturing, reliability and availability, second-hand products
