Title:Reliability Design of Mechanical Systems Subject to Repetitive Stresses
VOLUME: 8 ISSUE: 3
Author(s):Seong-Woo Woo and Dennis L. O’Neal
Affiliation:Korea Testing Co., Ltd., 106 Techno 2-Ro, Gwanpyeong-Dong, Yuseong-Gu, Daejeon City 305-509, Republic of Korea.
Keywords:Acceleration factor, approximated sample-size equation, failure mechanics, generalized sample size equation, lifestress
model, parametric ALT, reliability quantitative test specifications (RQ), sample size equation.
Abstract:The basic reliability concepts - parametric ALT plan, failure mechanism and design, acceleration
factor, and sample size equation were used in the development of a parametric accelerated
life testing method to assess the reliability quantitative test specifications (RQ) of mechanical systems
subjected to repetitive stresses. To calculate the acceleration factor of the mechanical system, a generalized
life-stress failure model with a new effort concept was derived and recommended. The new sample size equation
with the acceleration factor also enabled the parametric ALT to quickly evaluate the expected lifetime. This new parametric
ALT should help an engineer uncover the design parameters affecting reliability during the design process of the mechanical
system. Consequently, it should help companies improve product reliability and avoid recalls due to the product
failures in the field. As the improper design parameters in the design phase are experimentally identified by this new reliability
design method and recent patents are addressed, the mechanical system should improve in reliability as measured
by the increase in lifetime, LB, and the reduction in failure rate, λ.
