考虑真实时变环境应力的系统可靠性评估

传统可靠性评估方法只考虑产品处于恒定环境应力下的情况，然而工程实际中产品往往直接暴露于外界的自然环境中，所遭受的工作环境应力或贮存环境应力都是随时间变化的。针对此情况，引入典型地理位置的真实自然环境应力，使用六参数多项式拟合方法得到其环境应力变化趋势，并假定2种时变环境应力模式，在Nelson累积损伤模型的基础上，研究真实时变环境应力下基于加速寿命试验数据的产品可靠性评估方法。结果表明：产品在不同地理位置的可靠寿命差别较大，引入产品所处地理位置的真实环境应力，可更精确地评估产品的可靠性。

System reliability assessment under real time-varying environmental stress

The traditional reliability evaluation methods only consider the product under constant stress. However,products are often directly exposed to the outdoor natural environment in actual engineering,and the working environment stress or storage environment stress varies with time.Aimed to solve this problem, the natural environmental stress of the typical geographical location is introduced, and the environmental stress variation tendency is derived by using six-parameter polynomial fitting method.Moreover, two modes of the time-varying environmental stress are assumed, and on the basis of Nelson cumulative damage model, the product reliability evaluation method based on accelerated life test data is studied under the real time -varying environmental stress.The results show that the reliability life of the products at different geographical locations is quite different,and the reliability of the products can be evaluated more accurately by introducing the real environmental stress of the geographical location of the product.