4th International E-Conference on Engineering, Technology and Management - ICETM 2021
Author(s) : Dereje Engida Woldemichael, Muluneh Mekonnen Tulu, Samson Mekbib Atnaw, SEONG-WOO WOO
To enhance the design of mechanical system, parametric Accelerated Life Testing (ALT) as systematic reliability method suggests to evaluate the design of mechanical systems subjected to repeated stresses. It involves: (1) a parametric ALT plan formed on system BX lifetime, (2) a load examination, (3) a customized parametric ALTs with the design changes, and (4) an assessment of whether the design(s) of product attains the objective BX lifetime. We suggest a general life-stress model and sample size equation. As a test case, based on market data and a customized ALT, the redesign of hinge kit system (HKS) in a refrigerator was investigated. To carry out parametric ALTs, utilizing a force and moment balance analysis, the mechanical impact loading of HKS were computed in operating the refrigerator door. At the first ALT, the HKS failure occurred in the fracture of the kit housing, and oil damper leaked when the HKS broke. The failure modes and mechanisms found in the 1st ALT were alike to those of the failed samples obtained from the marketplace. The missing design parameters of the HKS included the stress raisers such as corner rounding and rib of the housing in HKS, the oil seal in the oil damper, and the material of the cover housing. In the second ALT, the cover housing fractured. The missing design parameter of the cover housing in the HKS was the plastics material. As a corrective action plan, we modified the cover housing from plastic to aluminum. After ALTs, the lifetime of the redesigned HKS was reassured to be a B1 life 10 years with a yearly failure rate of 0.1%.