Research On Condition-Based Maintenance Strategy Of Accelerated Degrading Equipment Considering Imperfect Maintenance

The performance of the equipment will inevitably degrade in the process of use,and degradation to a certain degree will lead to breakdown or failure,which will cause serious losses to the enterprise.To prevent such a situation,enterprises need to repair or maintain the equipment in a timely manner.However,the current commonly used corrective maintenance or periodic maintenance methods lack flexibility,waste resources and other shortcomings,therefore,enterprises urgently need a more costeffective maintenance method.With the development of intelligent detection and other industrial technologies,the Condition-Based Maintenance(CBM)method is gaining more and more attention,which can be used to know the degradation status of equipment with the help of sensors and other technologies,so that Preventive Maintenance(PM)activities can be scheduled in a timely and reasonable manner.Constrained by various realistic conditions,maintenance is usually imperfect.After Imperfect Maintenance,the degraded state of the equipment cannot be restored to a brand new state,which is reflected in the fact that not only the amount of degradation cannot be reduced to zero,but also the degradation process will be accelerated after the maintenance due to the destruction of the physical mechanism or structural strength of the internal materials of the equipment.In this paper,we fully consider the dual impact of Imperfect Maintenance on the amount and rate of equipment degradation,the impact of equipment degradation on product quality,and then design a reasonable CBM strategy for accelerated degradation equipment.The research in this paper is divided into the following main aspects.(1)Targeted improvements to address the shortcomings of the current research status.From the perspective of the equipment user,the accelerated degradation equipment is used as the research object.The Gamma process is used to represent the random degradation process of the equipment.Residual Damage and acceleration factor are introduced to represent the dual effects of imperfect maintenance on the amount and rate of equipment degradation,and the number of defective products is used to represent the effect of equipment degradation on product quality.Based on the payoff renewal theory,the CBM model of accelerated degradation equipment is constructed with the average cost rate of the equipment under long-term operation conditions as the optimization object.(2)In order to minimize the average cost rate,a CBM strategy is proposed,including a non-fixed-period inspection strategy and a preventive replacement strategy.In order to avoid premature equipment failure,the non-fixed-period inspection strategy fully considers the actual degradation state of the accelerated degradation equipment in each maintenance cycle,and thus flexibly sets different size of inspection intervals;meanwhile,for reliability and economy reasons,a PM number threshold is set,and the equipment is preventively replaced when the PM number reaches the threshold before the degradation breakdown occurs.(3)A grid search algorithm and a Monte Carlo simulation algorithm based on sequential sampling are designed to solve the CBM model for accelerated degradation equipment,and the feasibility of the proposed CBM strategy is verified by numerical experiments.The effectiveness of the proposed CBM strategy is verified by comparing it with the tradition CBM strategy considering fixed inspection cycles based on two evaluation indexes,namely,the average cost rate and the length of equipment life cycle.Finding that the CBM strategy proposed in this paper can extend the length of equipment life cycle while reducing the average cost rate.A sensibility analysis of the experimental results on key parameters is also conducted and some management insights are given.