高精度小样本延寿方法

Small-sample Life Extension Method with High Precision

当飞机、起落架、发动机叶片等产品在外场服役至其出厂前确定的安全使用寿命(高置信度、高可靠度的可靠寿命单侧置信下限)时,将面临延寿问题。传统方法需要选取若干个(大型产品通常为1个)待延寿产品进行寿命试验,这不但耗费大量的人力物力,而且因试样少信息量小,评估得到的寿命精度还不高。对此,本文提出一种高精度小样本延寿方法,该方法能够充分开发利用该型号产品大量的外场服役寿命数据,并结合其出厂前的定寿试验数据和延寿试验得到的寿命数据,重新对该产品的安全寿命进行评估,得到新的精度更高的安全寿命。虽然试验数据是小样本,但是外场服役数据量很大,且比试验数据更加真实可信,从而实现高精度小样本延寿。文中针对电子产品、机械产品和机电产品寿命所遵循的指数分布、两参数Weibull分布和对数正态分布情况进行了详细讨论,并给出一种延寿试验设计方法。

When outfield products such as aircraft,landing gears,and engine blades reach their safe life(i.e.,the lower confidence limit of reliable life with high confidence and high reliability)determined before delivery,life extension work has to be conducted.Traditional methods select several samples(generally one for the large product)for life extension test,consuming many resources.And the life assessment accuracy is not yet high due to the small sample and little information.Aiming at this problem,this paper proposes a small-sample life extension method with high precision.In the method,the product's outfield life data are fully developed.Combining them with life data from life determination and extension tests,a higher precision safe life is reassessed.Though the test data are small-sample,the service data are more authentic and their amount is large.Thus,the high-precision and small-sample life extension is realized.In the paper,exponential,two-parameter Weibull,and lognormal life distributions for electronic,mechanical,and electromechanical products are discussed in detail,respectively.And corresponding life extension test design methods are also provided.