Optimal time plan in accelerated degradation testing

Many highly reliable products are designed to function for years without failure. For such systems accelerated degradation testing may provide significance information about the reliability properties of system. In this paper, we propose c-optimality criterion obtaining optimal designs constant-stress tests where path follow a linear mixed effects model. The present work is mainly concerned with developing in terms time variable rather than considering an design stress which usually considered majority literature. Finally, numerical examples presented and sensitivity analysis procedures conducted evaluating robustness as well standard against misspecifications nominal values.