针对具有“浴盆”型失效率变化规律的产品，分析“浴盆”型失效率曲线在不同阶段的变化特征；根据“浴盆”型失效率变化规律所反映的产品寿命概率分布特征，构建产品的寿命概率分布模型，给出相应的可靠度、失效率以及平均寿命计算模型。在此基础上，研究比例参数、第一尺度参数、第一形状参数、第二尺度参数、第二形状参数等对概率分布特征的影响，运用建立的概率分布模型对具有“浴盆”型失效率变化规律的零部件寿命概率分布特征进行参数拟合。研究表明，建立的概率模型能够较好地描述产品的寿命概率分布特征，可以完整地刻画产品在不同阶段的失效率变化规律。
For the products with bathtub-shaped failure rate changing rule, the characteristics of bathtub-shaped failure rate curve is analyzed and the factors affecting the failure rate change in the different stages are also studied. According to the probability distribution characteristics reflected by the bathtub-shaped failure rate changing rule, the probability distribution model of products is developed, and the corresponding models of reliability, failure rate and mean time to failure are derived. Then, the effect of parameters including the ratio parameter, the first scale parameter, the first shape parameter, the second scale parameter and the second shape parameter on the probability distribution characteristics is studied. As an example, the life probability distribution characteristics of component with bathtub-shaped failure rate changing rule is fitted with the probability model proposed. The results show that the probability model developed can be used to describe the life probability distribution characteristics of products more correctively, and it can reflect the failure rate change rule of products in the different stages completely.
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