Reliability assessment of LED luminaires based on step-stress accelerated degradation test

Abstract

Currently, reliability of LED luminaires, especially LED system, has become one of the hottest researches of LED industry. However, in existing literature, almost none of them utilized step-stress accelerated degradation test (SSADT) to assess reliability of LED luminaires. While indoor lighting is close correlated to people's life, this paper takes LED bulb which produced by two different Chinese companies as the research objective. And the optic fluxes of all the samples are inspected and considered as the initial value. Because temperature is one of the most important parameters which affect LED's lifetime, So a step-temperature ADT is conducted. This paper chooses L70 as the failure criterion (if a LED luminaires failed, it's SSADT test would be stopped). Then four degradation models are used for fitting the degradation track of luminous flux of the test samples. After that, this paper assumed the pseudo failure lifetime follows normal distribution, Weibull distribution and lognormal distribution and conducted distribution assumption inspection, respectively. Finally, Using Arrhenius model and MATLAB to obtain the mean lifetime and reliability curve of the samples. By Comparing, it can be observed that the mean lifetime of LED samples is not as much as the lifetime that provided by the company.