Abstract: The traditional reliability model of components cannot well reflect the effect of loads of stochastic-changed amplitude and strength degradation on reliability due to neglecting changes of reliability and failure rate with using time. The variation rules of strength, load and reliability of mechanical components are studied with the change of time. Considering loads of stochastic-changed amplitude and strength degradation, a functional equation model for dynamic reliability of mechanical components is established on the basis of random process and order statistics theory, and then dynamic reliability index and reliability of components are obtained by using order-second moment method and perturbation method. Using the mathematical model of dynamic reliability established, and combining the reliability design theory with sensitivity analysis method, a numerical method for dynamic reliability sensitivity design is proposed, and the design of dynamic reliability sensitivity is extensively discussed. A torsion-bar is taken as an example, the variation rules of dynamic reliability sensitivity of parameters are given and the effects of design parameters on the reliability of torsion-bar are analyzed. The method presented provides the theoretical basis for reliability design of mechanical components.

Key words: Dynamic reliability, Failure rate, Reliability analysis, Sensitivity, Stochastic process