Design for Lifecycle Cost Using Time-Dependent Reliability

Abstract

Reliability is an important engineering requirement for consistently delivering acceptable product performance through time. As time progresses, the product may fail due to time phenomena such as time-dependent operating conditions, component degradation, etc. The degradation of reliability with time may increase the lifecycle cost due to potential warranty costs, repairs, and loss of market share, affecting the sustainability of environmentally friendly products. In the design for lifecycle cost, we must account for product quality and time-dependent reliability. Quality is a measure of our confidence that the product conforms to specifications as it leaves the factory. Quality is time independent, and reliability is time dependent. This article presents a design methodology to determine the optimal design of time-dependent multiresponse systems by minimizing the cost during the life of the product. The conformance of multiple responses is treated in a series-system fashion. The lifecycle cost includes a production, an inspection, and an expected variable cost. All costs depend on quality and/or reliability. The key to our approach is the calculation of the so-called system cumulative probability of failure. For that, we use an equivalent time-invariant “composite” limit state and a niching genetic algorithm with lazy learning metamodeling. A two-mass vibratory system example and an automotive roller clutch example demonstrate the calculation of the cumulative probability of failure and the design for lifecycle cost.

Dynamic Reliability-Based Robust Design with Time-Variant Probabilistic Constraints

“…The Kriging model is able to evaluate the accuracy of estimation for any particular input point based on the estimated mean square error according to Eq. (24) and (25).…”

“…In the literature, different methods have been developed to tackle this challenge, including both analytical and simulation-based methods. The composite limit state approach [25] and the out-crossing rate approach [26] are two of representatives.…”

Accelerated Life Testing (ALT) Design Based on Computational Reliability Analysis

“…When the failure threshold is low, the Poisson assumption regarding the outcrossing rate may result in significant error in the reliability estimate. In order to improve the accuracy of reliability analysis, other methods have been developed by releasing the Poisson assumption, such as the composite limit-state function method, 18 the stochastic discretization method, 31 and first-order sampling approach (FOSA). 19 In FOSA, F T (t) up to the time interval of interest can be obtained from one analysis.…”

“…In order to investigate the degradation of product reliability over time, a group of time-dependent reliability analysis methods have been developed recent years. Examples of time-dependent reliability analysis methods include the PHI2 method developed by Andrieu-Renaud et al 15 , the probability density evolution method, 16 the upcrossing rate-based method, 17 the composite limit-state function method, 18 the first-order sampling approach, 19 and importance sampling approaches proposed by Mori and Ellingwood, 20 Dey and Mahadevan, 21 and Singh and Mourelatos. 22 Because time-dependent reliability is connected to ALT through the relationship between life and reliability, integration of physics-informed time-dependent reliability analysis models and ALT methods is a promising way of designing optimal testing plans to reduce product development cost and time.…”

Ship design evaluation subject to carbon emission policymaking using a Markov decision process framework

“…Evaluation methods such as utility theory, cost-benefit analysis, and optimization aid in selecting among alternatives, while techniques apply subjective or imprecise probabilities, intervals, possibility theory, or evidence theory to model uncertainty (Dym et al, 2005). Network theory (Silver and De Weck, 2007;Siddiqi, 2006), stock-option theory (Walton, 2002), time-dependent reliability theory (Singh et al, 2010, Frangopol et al 2011, and game theory (Briceno and Mavris 2006;Coulter and Bras, 1997) have been applied to value and direct design change.…”