Reliability assessment with uncertain thresholds considering degradation and shock

In fields such as aerospace and nuclear materials, there is no large amount of sample data available for reference due to cost and experimental environment; probabilistic theory based on large sample data is not suitable for assessing the reliability of equipment. Due to the lack of a large amount of failure data, the reliability assessment of the equipment has to rely on the empirical data of experts in the field, which have artificial cognitive uncertainty, and uncertainty theory is an effective mathematical tool to analyze the artificial cognitive data. In the uncertain environment, this paper considers the competing failure processes where the failure threshold is an uncertain variable, calculates the reliability of the device under three different shock models, and compares the reliability of the uncertain thresholds with the reliability of the constant thresholds. The results show that in different periods of equipment operation, the reliability of the uncertain thresholds is different with the reliability of the constant thresholds. If the threshold is simply regarded as a known constant, it will cause inaccuracies in the reliability assessment of the system, miss the best maintenance time, and cause unnecessary losses. Taking the microelectronic mechanical system as an example, the superiority of the proposed model is illustrated.