Optimal Design of Multi-Stress Accelerated Degradation Test within Irregular Test Region

Abstract

Motorized spindle is the key functional part of the computer numerical control machine tool and its lifetime determines the reliability level of the machine tool to a great extent. Many efficient plans have been obtained for electronic products but how to design an efficient accelerated degradation test plan for the motorized spindle is still a problem to be solved. In this paper, considering the condition that the loaded stresses of the motorized spindle in practice may not reach their highest levels simultaneously, a novel optimization design method of the accelerated degradation test is proposed within the irregular test region. The orthogonal design theory and the uniform design theory are applied to determine the alternative test plans within the irregular test region for different numbers of stress levels. A numerical example is presented to illustrate the effectiveness of the proposed method. Finally, the sensitivity analysis is conducted to assess the robustness of the optimum plan on parameter variation.