Reliability design and case study of mechanical system like a hinge kit system in refrigerator subjected to repetitive stresses

Abstract To improve the reliability of mechanical systems with inherited faulty designs, a reliability methodology utilizing parametric accelerated life testing (ALT) is suggested. 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 uncover the design parameters affecting reliability during the design process of a mechanical system. As a case study, the hinge kit system (HKS) of a door in a refrigerator was redesigned to improve its reliability. Using a force and moment balance analysis, the mechanical impact loads in closing the door of the HKS were calculated. During the first ALT, the kit housing in the HKS fractured and the oil damper leaked when the HKS failed. The faults in the design of the HKS included the weakness of the housing hinge kit and the oil sealing structure of the oil damper. In the second ALT, the hinge cover fractured due to the impact of the damper support. The material in the hinge cover in the HKS was changed from plastic to aluminum. After three rounds of parametric ALTs, the reliability of the new HKS was guaranteed to be a 10 year life with an accumulated failure rate of 1%.