Seongwoo Woo

Abstract:

The mechanical products such as automobile, airplane, and refrigerator [1] manage power to accomplish a task that involves forces and movement, which eventually produce mechanical advantages by adapting product mechanisms. A refrigerator consists of several different modules and parts – compressor, doors, cabinet, heat exchanger, shelves and drawers, etc. Its lifetime is determined by design faults. To avoid the mechanical system such as a compressor failure in the field [2], it must be designed to handle the operating conditions imposed by the consumers who purchase and use. Any faulty designs therefore should be identified and modified through statistical methodology [3] or reliability testing [4] before a product is launched. However, they requires huge computations but have no results because of not figuring out failure mechanics. That is, if there are faulty designs that cause an inadequacy of strength (or stiffness) when a product is subjected to repetitive loads, the product will collapse before its expected lifetime due to fatigue failure. Based on failure mechanism and design, new reliability methodology – parametric Accelerated Life Testing (ALT) – suggests to assess the design of mechanical systems subjected to repetitive stresses. It includes: (1) a parametric ALT plan based on product BX lifetime, (2) a load analysis for accelerated life time test, (3) a tailored sample of parametric ALTs with the design modifications, and (4) an evaluation of whether the final design(s) of the product achieves the target BX lifetime. So we suggest a generalized life-stress failure model with a new effort concept, accelerated factor, and sample size equation with the acceleration factor. This new parametric ALT should help an engineer uncover the design parameters of the mechanical system affecting reliability during the design process. As the improper design parameters are experimentally identified, the mechanical system should improve in reliability as measured by the increase in lifetime, and the reduction in failure rate. Consequently, companies can avoid recalls due to the product failures in the field.