Design of Optimum Simple Step-Stress Accelerated Life Testing Plans

Accelerated life testing (ALT) is widely conducted to obtain failure-time data in a much shorter time and to make inference about reliability at normal conditions. The accuracy of the reliability prediction is dependent on well-designed ALT plans. A stepstress ALT allows the test condition to change at a given time or upon the occurrence of a specified number of failures. In this paper, we propose a procedure to determine the parameters of the optimum simple step-stress testing plan so that the reliability prediction at normal conditions is accurately determined. We investigate efficient procedures to estimate most, if not all, of the ALT parameters under different operating conditions. The objective function is formulated as a nonlinear programming problem. The resultant optimum plan is demonstrated through numerical example and sensitivity analysis.