Additive Weibull Model for Reliability Analysis
Volume 5, Number 3, April 2009 - Paper 5 - pp. 243 - 250
S. G. G. USGAONKAR1 and V. MARIAPPAN21Faculty, Department of Mechanical Engineering Government Polytechnic, Bicholim-Goa
2Professor and Head, Department of Mechanical Engineering, P.C. College of Engineering, Verna-Goa, India: 403722
(Received on March 17, 2007, revised on November 03, 2008)
Statistical distributions of time to failure for many mechanical systems reveal bathtub-shaped failure rate in practice. Bathtub shaped failure rate is very much useful in reliability engineering for the determination of burn-in and plays key role in provisions of warranty. The traditional Weibull distribution can cover the profile piecewise only and there are very few practical models to model bathtub-shaped failure rate. The Additive Weibull model discussed in this paper is based on adding two Weibull survival functions. Some simplifications of the model are presented and the parameter estimation methods based on the graphical estimation technique are discussed. Various case studies discussed in this paper illustrate the applicability of the model. Results and discussions on cases gave some interesting utilities, which are also presented in this paper.
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