An Improved Inspection Strategy Analysis for Long-Term Storage Product

For most military products, such as missiles, torpedoes and their spare parts, after production they must be stored for long time until being put into operational use. During the storage period, the inspections are performed periodically to monitor the functionality of products. However, such inspections expose products to working conditions, yielding significant extra degradation increments. The number of inspections need to be optimized to make the trade-off between the accuracy of parameter estimation and the degradation caused by the inspections. Therefore, during storage opportune inspections are demanded. In this study, the degradation model with binary degradation rates regarding the inspection and storage period is introduced and the corresponding parameter estimating approach is given based on Maximum Likelihood Estimation (MLE). Moreover, we improve the widely-adopted periodic inspection strategy into a two-stage pattern that the inspection is less frequent in the first stage by adopting a larger interval. The availability and feasibility of the proposed degradation model and inspection strategy are verified through three numerical studies.