Title: Improving the reliability of mechanical components that have failed in the field due to repetitive stress

Abstract

To improve the reliability of mechanical parts that have failed in the field, a reliability methodology for parametric accelerated life testing (ALT) is proposed. It consists of: (1) a parametric ALT plan, (2) a load analysis, (3) a tailored series of parametric ALTs with action plans, and (4) an evaluation of the final designs to ensure the design requirements are satisfied. This parametric ALT should help an engineer reproduce the fractured or failed parts in a product subject edto repetitive loading and correct the faulty designs. As a test case, the helix upper dispenser of a refrigerator icemaker fractured in field was studied. Using a load analysis, we discerned that the helix upper dispenser fracture was due to repetitive loads and a faulty design with a 2 mm gap between the blade dispenser and the helix upper dispenser. During the first and second ALTs, the fracture in the helix upper dispenser was reproduced. The failure modes and mechanisms found were similar to those of the failed sample in field. As an action plan, the design of the helix upper dispenser was modified by eliminating the 2 mm gap and adding enforced ribs. In the third ALT there were no problems. After three rounds of parametric ALTs, the reliability of the e helix upper dispenser was guaranteed as a 10-year life with an accumulated failure rate of 1%.

Biography

Seongwoo Woo has a BS and MS in Mechanical Engineering, and he has obtained PhD in Mechanical Engineering from Texas A&M. He major in energy system such as HVAC and its heat transfer, optimal design and control of refrigerator, reliability design of mechanical components, and failure Analysis of thermal components in marketplace using the Non-destructive such as SEM & XRAY. Especially, he developed parametric accelerated life testing (ALT) as new reliability methodology. If there is design fault in the mechanical system that is subjected to repetitive stress, it will fail in its lifetime. Engineer should find the design faults by parametric ALT before product launches. In 1992–1997 he worked in Agency for Defense Development, Chinhae, South Korea, where he has researcher in charge of Development of Naval weapon System. In 2000-2010 he had been working as a Senior Reliability Engineer in Side-by-Side Refrigerator Division, Digital Appliance, SAMSUNG Electronics, where he focused on enhancing the life of refrigerator as using parametric the accelerating life testing. Now he is working as associate professor in mechanical department, Addis Ababa Science & Technology University