Keywords: corrective replacement, cost analysis, preventive replacement, hazard function reliability, optimisation, gearbox cracks, vibration measurement, optimisation, gearbox replacement policy, gearbox reliability, cracked gear tooth, Weibull density function degradation, torsional vibration, vehicle vibration
Optimisation of gearbox replacement policy using vibration measurement data
Gearbox system reliability is a critical factor in the success of any industrial project. Poor reliability directly affects both the project's revenue stream through increased operation and maintenance (O&M) costs and reduced availability to the system due to its downtime. Indirectly, the acceptance of the system by the financial and developer communities as a viable enterprise is influenced by the risk associated with the capital equipment reliability; increased risk, or at least the perception of increased risk, is generally accompanied by increased financing fees or interest rates. However, this paper explores a reliability based on a developed an analytical mathematical method for predicting remaining lifetime of cracked gear tooth. The development is focused specifically on the investigation of a generalised statistical method for characterising and predicting system Weibull density function degradation (hazard rate). Using this method, optimal preventive age replacement policy is determined to maximise gearbox system reliability, and consequently an optimal cost analysis can be estimated. A simple geared system is used as a medium for real data collection, where the torsional vibration acceleration was measured and analysed. The results indicate that the knowledge of the remaining lifetime and the optimised replacement cost of the faulty gear can enhance the process of scheduling maintenance, ordering spare parts and using resources; consequently a reduction of maintenance cost.