Reliability assessment with uncertain thresholds considering degradation-shock

Abstract There are often many reasons for equipment failure. When the performance of a certain aspect drops to a certain threshold, the equipment will fail. Affected by other factors, the threshold is uncertain. A reliability model of uncertain thresholds where degradation and external shocks compete with each other is established, and the reliability of the model are evaluated according to uncertainty theory. Under three different shock types, the reliability of the equipment is obtained. The reliability with uncertain thresholds and the reliability with constants thresholds are compared. The results show that in different periods of equipment operation, the reliability of the uncertain thresholds is different with the reliability of the constants thresholds. If the threshold is simply regarded as a known constant, it will cause inaccuracies in the reliability assessment of the system, and miss the best maintenance time, causing unnecessary losses. Taking the microelectronic mechanical system as an example, the superiority of the proposed model is illustrated.