A Life Prediction Model for High-Reliability Products and Its Application to VFD Based on Constant-Stress ADTs

摘要

For many high-reliability and long-life products, the accuracies of some existing life predictionmodels are not high enough, which may limit their fast development. For this purpose, fourgroups of constant-stress accelerated degradation tests (ADTs) were carried out by increasingthe temperature of a vacuum fluorescent display (VFD) cathodic filament, and the equivalentaverage luminance degradation model (EALDM) was proposed to predict VFD life. In thismodel, firstly, a two-parameter Weibull function was used to fit average test data at each acceleratedstress, and the corresponding formula of luminance degradation was obtained.Secondly, a power function was determined to fit multi-groups of data points formed byan accelerated stress and time at different given luminance, and then the work time undernormal stress was extrapolated. Finally, by reusing the Weibull function to fit the data points,including the work time and given luminance, the life prediction of products was achieved. Theresults indicate that the test design of constant-stress ADTs is correct and feasible; the Weibullfunction well reveals the VFD luminance decaying law at both accelerated and normal stresses,and the power function objectively reflects the relationship between work time and stress. It isfound by comparing the predicted life with the reference value that EALDM has high precision,which paves the way for following research in life prediction methodology and acts as a guidefor professional technicians.