对于需要考虑多元性能参数退化及其相关性的产品,如何进行加速退化试验方案设计以提高其估计精度问题,提出恒定应力加速退化试验方案优化设计的准则与方法;以产品在正常工作应力水平下,达到所规定的使用寿命时可靠度估计值的方差最小为目标;在给定正常工作应力水平、最高试验应力水平及各应力水平下试验截尾时间和性能参数退化量测试次数等试验参数后,以各试验应力水平和样本分配比例为设计变量,应用极大似然估计理论,建立基于多元性能参数的加速退化试验方案优化设计的数学模型,对电液伺服机构用丁腈橡胶O形密封圈的加速退化试验方案优化设计结果表明,经优化的试验方案能提高产品可靠度的估计精度,在相同置信度下可减少试验所需的样本量。
Optimal design of accelerated degradation test plan could raise the estimation precision,so the rule and method of optimal design based on constant-stresses accelerated degradation test is proposed when there is a need for considering products of the degradation of multiple performance parameters and the dependence.Under given normal working stress level,the aim is to minimum the variance of reliability estimates when products reach required life.Given the normal working stress level,the highest test stress level,test truncation time under each stress level,performance parameters degradations and testing number of times and so on,considering the test stress level and the ratio of the sample as design variables,apply maximum likelihood estimation theory,established mathematical model of accelerated degradation test plan optimal design,which based on multiple performance parameters.The result about accelerated degradation test plan optimal design of application of nitrile butadiene rubber O-ring on the electro-hydraulic servo mechanism,shows that optimized test plan can raise estimation precision of reliability and that the numbers of test samples also could be cut down under the same degree of confidence.