TITLE:
Reliability Design of Ice-Maker System Subjected to Repetitive Loading
AUTHORS:
Seong-Woo Woo
KEYWORDS:
Reliability Design, Sample Size Equation, Acceleration Factor, Parametric Accelerated Life Testing, Helix Upper Dispenser, Reliability Quantitative Test Specifications (RQ)
JOURNAL NAME:
Engineering,
Vol.8 No.9,
September
29,
2016
ABSTRACT: Parametric Accelerated Life Testing (ALT) was used to improve the reliability of ice-maker system with a fractured helix upper dispenser in field. By using bond graphs and state equations, a variety of mechanical loads in the assembly were analyzed. The acceleration factor was derived from a generalized life-stress failure model with a new load concept. To reproduce the failure modes and mechanisms causing the fracture, new sample size equation was derived. The sample size equation with the acceleration factor also enabled the parametric accelerated life testing to quickly reproduce early failure in field. Consequently, the failure modes and mechanisms found were identical with those of the failed sample. The design of this testing should help an engineer uncover the design parameters affecting the reliability of fractured helix upper dispenser in field. By eliminating the design flaws, gaps and weldline, the B1 life of the redesign of helix upper dispenser is now guaranteed to be over 10 years with a yearly failure rate of 0.1% that is the reliability quantitative test specifications (RQ).