A criticAlity importAnce-bAsed spAre ordering policy for multi-component degrAded systems opArtA nA kryterium krytyczności politykA zAmAwiAniA części zAmiennych do zdegrAdowAnych systemów wieloelementowychWith the increasing complexity and variety of production systems, more attention is being paid to preventive replacement on multicomponent systems. Each component is non-identical and has its own degradation process. In this paper, we propose a criticality importance-based spare ordering policy for a complex system, which consists of multiple series-parallel degrading components. Replacement action is triggered whenever the system reliability drops below a lower threshold and spares for replacement are available. Our policy mainly consists of two steps: (1) determine which components to be replaced;(2) determine when to order spares for components selected. In step 1, when the replacement action is triggered, we select components that most need to be replaced within the system in accordance with the optimum ranking of components until the system meets an upper reliability threshold. In step 2, a spare ordering policy for components selected is made and the optimal spare ordering time is obtained by minimizing the expected replacement cost during the once replacement cycle. Finally, a numerical example is given to illustrate the proposed multi-spare ordering policy. Moreover, the proposed policy is of significance for safety-critical systems such as substation automation system, bridge system, nuclear power plants and aerospace equipment.
An efficient condition-based predictive spare ordering approach is the key to guarantee safe operation, improve service quality, and reduce maintenance costs under a predefined lower availability threshold. In this paper, we propose a condition-based predictive order model (CBPO) for a mechanical component, whose degradation path is modeled as inverse Gaussian (IG) process with covariate effect. The CBPO is dependent on the remaining useful life (RUL), random lead-time, speed-up lead-time degree, and availability threshold. RUL estimation is obtained through the IG degradation process at each inspection time. Both regular lead-time and expedited lead-time considered in RUL-based spare ordering policy can be cost-effective and reduce losses caused by unexpected failure. Speed-up lead-time can meet the urgent needs for spare parts on site. The decision variable of CBPO is the spare ordering time. Based on the CBPO under the lower availability threshold constraint, the objective of this study is to determine the optimal spare ordering time such that the expected cost rate is minimized. Finally, a case study of the mechanical spindle is presented to illustrate the proposed model and sensitivity analysis on critical parameters is performed.
In order to establish the framework for aircraft life-cycle data management and ensure the efficient implementation of maintenance information management of in-service aircraft, the characteristics of maintenance information management of civil aircraft in service were analyzed. BOM views were classified, and a BOM multi-view model was constructed. By analyzing the main mapping forms of BOM multi-views, the node types of BOM multi-view were defined, the mapping rules of BOM multi-view model were proposed, and the mapping algorithm of BOM multi-view model was designed and implemented. Finally, method validation was performed by the BOM mapping of 48-section torsion box of a certain aircraft. The results show that, the mapping of EBOM to M-BOM is realized effectively, ensuring the full integration of the information management structure in the in-service maintenance phase and the development phase, and ensuring the consistency of the aircraft life-cycle data management framework.
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