Design for Lifecycle Cost Using Time-Dependent Reliability

2010 ◽  
Vol 132 (9) ◽  
Author(s):  
Amandeep Singh ◽  
Zissimos P. Mourelatos ◽  
Jing Li
Keyword(s):  
Limit State ◽  
Probability Of Failure ◽  
Operating Conditions ◽  
Time Dependent ◽  
Variable Cost ◽  
Cumulative Probability ◽  
Vibratory System ◽  
Equivalent Time ◽  
Engineering Requirement ◽  
Warranty Costs

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.

Design for Lifecycle Cost and Preventive Maintenance Using Time-Dependent Reliability

2010 ◽  
Vol 118-120 ◽  
pp. 10-16 ◽  
Author(s):  
Amandeep Singh ◽  
Zissimos P. Mourelatos ◽  
Jing Li
Keyword(s):  
Preventive Maintenance ◽  
Operating Conditions ◽  
Time Dependent ◽  
Variable Cost ◽  
System Response ◽  
Time Period ◽  
Engineering Requirement ◽  
Response Systems ◽  
Warranty Costs ◽  
The Cost

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. In design for lifecycle cost and preventive maintenance, 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. Reliability depends on 1) the probability that the system will perform its intended function successfully for a specified interval of time, and 2) on the probability that the system response will not exceed an objectionable by the customer or operator, threshold for a certain time period. Quality is time-independent, and reliability is time-dependent. This paper presents a methodology to determine the optimal design and preventive maintenance of time-dependent, multi-response systems, by minimizing the cost during the life of the product. The lifecycle cost includes a production, an inspection, and an expected variable cost. All costs depend on quality and/or reliability. A roller clutch example highlights the design methodology for lifecycle cost.

A Simulation-Based Random Process Method for Time-Dependent Reliability of Dynamic Systems

2010 ◽  
Author(s):  
Amandeep Singh ◽  
Zissimos P. Mourelatos ◽  
Efstratios Nikolaidis
Keyword(s):  
Random Process ◽  
Operating Conditions ◽  
Time Dependent ◽  
Process Time ◽  
Cumulative Probability ◽  
Repairable Systems ◽  
First Passage ◽  
True Value ◽  
Warranty Costs ◽  
Short Time

Reliability is an important engineering requirement for consistently delivering acceptable product performance through time. As time progresses, a product may fail due to time-dependent operating conditions and material properties, and component degradation. The reliability degradation with time may significantly increase the lifecycle cost due to potential warranty costs, repairs and loss of market share. In this work, we consider the first-passage reliability, which accounts for the first time failure of non-repairable systems. Methods are available that provide an upper bound to the true reliability, but they may overestimate the true value considerably. This paper proposes a methodology to calculate the cumulative probability of failure (probability of first passage or upcrossing) of a dynamic system with random properties, driven by an ergodic input random process. Time series modeling is used to characterize the input random process based on data from a “short” time period (e.g. seconds) from only one sample function of the random process. Sample functions of the output random process are calculated for the same “short” time because it is usually impractical to perform the calculation for a “long” duration (e.g. hours). The proposed methodology calculates the time-dependent reliability, at a “long” time using an accurate “extrapolation” procedure of the failure rate. A representative example of a quarter car model subjected to a stochastic road excitation demonstrates the improved accuracy of the proposed method compared with available methods.

Design for Lifecycle Cost Using Time-Dependent Reliability

2009 ◽  
Author(s):  
Amandeep Singh ◽  
Zissimos P. Mourelatos ◽  
Jing Li
Keyword(s):  
Distribution Function ◽  
Design Methodology ◽  
Cumulative Distribution Function ◽  
Limit State ◽  
Operating Conditions ◽  
Time Dependent ◽  
Cumulative Distribution ◽  
Variable Cost ◽  
System Response ◽  
Soft Failure

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. In 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. Reliability depends on 1) the probability that the system will perform its intended function successfully for a specified interval of time (no hard failure), and 2) on the probability that the system response will not exceed an objectionable by the customer or operator, threshold for a certain time period (no soft failure). Quality is time-independent, and reliability is time-dependent. This article presents a design methodology to determine the optimal design of time-dependent, multi-response 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 distribution function (time-dependent probability of failure). For that we use an equivalent time-invariant “composite” limit state which is accurate for monotonic or non-monotonic in time, systems. Examples highlight the calculation of the cumulative distribution function and the design methodology for lifecycle cost.

Prediction of Fracture Failure of Steel Pipes With Sharp Corrosion Pits Using Time-Dependent Reliability Method With Lognormal Process

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Guoyang Fu ◽  
Wei Yang ◽  
Wenni Deng ◽  
Chun-Qing Li ◽  
Sujeeva Setunge
Keyword(s):  
Fracture Toughness ◽  
Limit State ◽  
Probability Of Failure ◽  
Considerable Effect ◽  
Time Dependent ◽  
Pipe Failure ◽  
Load Effect ◽  
Steel Pipes ◽  
Reliability Method ◽  
Corrosion Pits

This paper presents a reliability-based methodology for assessing fracture failures of steel pipes with sharp corrosion pits. Based on newly developed models of elastic fracture toughness, the simple criterion of stress intensity factor (SIF) is used to establish the limit state functions for pipes with sharp corrosion pits in the longitudinal and circumferential directions. A stochastic model of load effect is developed and a time-dependent reliability method based on first passage probability for nonstationary lognormal processes is employed to quantify the probability of failure and predict the remaining service life. After applying the methodology to a case study, sensitivity analysis is carried out to identify the most influential variables on the probability of failure. It is found in the paper that the correlation coefficient has a considerable effect on probability of failure of steel pipes with sharp corrosion pits and that the larger the mode I fracture toughness is, the smaller the probability of pipe failure is.

scholarly journals Thermo-Viscoelastic Response of 3D Braided Composites Based on a Novel FsMsFE Method

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 271
Author(s):  
Jun-Jun Zhai ◽  
Xiang-Xia Kong ◽  
Lu-Chen Wang
Keyword(s):  
Finite Element ◽  
Cell Model ◽  
Structural Parameters ◽  
Thermal Relaxation ◽  
Viscoelastic Behavior ◽  
Unit Cell ◽  
Time Dependent ◽  
3D Braided Composites ◽  
Equivalent Time ◽  
Representative Unit Cell

A homogenization-based five-step multi-scale finite element (FsMsFE) simulation framework is developed to describe the time-temperature-dependent viscoelastic behavior of 3D braided four-directional composites. The current analysis was performed via three-scale finite element models, the fiber/matrix (microscopic) representative unit cell (RUC) model, the yarn/matrix (mesoscopic) representative unit cell model, and the macroscopic solid model with homogeneous property. Coupling the time-temperature equivalence principle, multi-phase finite element approach, Laplace transformation and Prony series fitting technology, the character of the stress relaxation behaviors at three scales subject to variation in temperature is investigated, and the equivalent time-dependent thermal expansion coefficients (TTEC), the equivalent time-dependent thermal relaxation modulus (TTRM) under micro-scale and meso-scale were predicted. Furthermore, the impacts of temperature, structural parameters and relaxation time on the time-dependent thermo-viscoelastic properties of 3D braided four-directional composites were studied.

Simplified Method for Time-Dependent Reliability Analysis of Aging Bridges Subjected to Nonstationary Loads

2016 ◽  
Vol 23 (01) ◽  
pp. 1650003
Author(s):  
Cao Wang ◽  
Quanwang Li
Keyword(s):  
Structural Reliability ◽  
Operating Conditions ◽  
Time Dependent ◽  
Structural Resistance ◽  
Simplified Method ◽  
Increasing Trend ◽  
Live Loads ◽  
Load Intensity ◽  
Existing Bridges ◽  
Dimensional Integral

The performance of existing bridges may deteriorate in time due to aggressive environmental or operating conditions in service, which may eventually cause changes in structural resistance and reliability beyond the baseline assumed for new ones. In addition, the increasing trend of live loads applied to the bridges, which has been reported in many researches, also contributes to the reduction of structural reliability. In order to perform time-dependent reliability assessment for aging bridges subjected to nonstationary loading process with improved efficiency, a simplified method is proposed in this paper, where lower dimensional integral is involved in the calculation of reliability. With the proposed method, time-dependent reliability of a real aging RC bridge is conducted, and the effect of nonstationarity in load intensity on structural reliability is investigated. It is found that structural reliability is sensitive to the increase of load intensity, and is less sensitive to the varying mechanism of load intensity.

Equivalent time-dependent scheduling problems

2009 ◽  
Vol 196 (3) ◽  
pp. 919-929 ◽  
Author(s):  
Stanisław Gawiejnowicz ◽  
Wiesław Kurc ◽  
Lidia Pankowska
Keyword(s):  
Time Dependent ◽  
Scheduling Problems ◽  
Equivalent Time

Statistical Method to Requalify Steel Grades During Conversion of Tankers to FPSO

2016 ◽  
Author(s):  
Philippe Cambos ◽  
Guy Parmentier
Keyword(s):  
Confidence Level ◽  
Probabilistic Model ◽  
Probabilistic Models ◽  
Empirical Distribution ◽  
Probability Of Failure ◽  
Operating Conditions ◽  
Existing Structures ◽  
Steel Grades ◽  
Determination Of Parameters ◽  
Acceptable Probability

During ship life, operating conditions may change, tanker may be converted into FPSO, and flag requirements may be modified. Generally these modifications have few impacts on existing structures; flag requirements only rarely are to be applied retroactively. Nevertheless in some cases modifications of operating condition may induce considerable consequences, making in the worst cases impossible any reengineering. For example converting a common tanker, built with plain steel of grade A into an Offshore Floating Unit able operating in cold region, may require a grade change corresponding to a grade B. It is obviously meaningless to replace all material just because material certificates. Steels used by shipyards have to fulfill Classification society’s requirements dealing with mechanical strength; generally shipbuilding corresponds to a small part of steelmaker’s production. For this reason steelmakers are reluctant to produce steels with mechanical properties corresponding exactly to the minima required. They generally deliver steels already in stock, with higher mechanical characteristics than required. In this case it can be taken advantage of this common practice. In order to demonstrate that the material fulfill the requirements of grade B it has been decided to adopt a statistic approach. At this stage there are two main issues, the first one is that it is needed to provide evidences that the actual material Charpy V characteristics fulfill the requirements of grade B; the second one is to provide these evidences with a minimum testing. To assess this assumption a random check has been carried out. Different probabilistic model have been tested in order to check common approaches and probabilistic model based on physical considerations. In the paper the main assumptions for estimating the minimum Charpy value main assumption in the probabilistic models are recalled, the behavior of empirical sample is examined, the parameters of probability laws fitting the empirical distribution and definitely as accuracy of probability law parameters determination is not perfect with a finite number of specimens the uncertainty in the determination of parameters is taken into account with confidence limits. According to the selected probabilistic model the minimum value corresponds to an acceptable probability of failure, taking into account the target confidence level, or is independent of any acceptable probability of failure and is defined with the same confidence level. At the end it is concluded that a random check with a data treatment assuming a random distribution of Charpy V test results distributed according to a Weibull probability law of the minimum allows providing evidences that with a sufficient confidence level the steel used for the considered structure fulfill the requirements of the new operating conditions.

Reliability of Buried Pipeline Using a Theory of Probability of Failure

2006 ◽  
Vol 110 ◽  
pp. 221-230 ◽  
Author(s):  
Ouk Sub Lee ◽  
Dong Hyeok Kim ◽  
Seon Soon Choi
Keyword(s):  
Failure Probability ◽  
Probability Of Failure ◽  
Operating Conditions ◽  
Reliability Estimation ◽  
Design Parameters ◽  
Buried Pipeline ◽  
Safety Level ◽  
First Order ◽  
Reliability Method ◽  
Corrosion Defects

The reliability estimation of buried pipeline with corrosion defects is presented. The reliability of corroded pipeline has been estimated by using a theory of probability of failure. And the reliability has been analyzed in accordance with a target safety level. The probability of failure is calculated using the FORM (first order reliability method). The changes in probability of failure corresponding to three corrosion models and eight failure pressure models are systematically investigated in detail. It is highly suggested that the plant designer should select appropriate operating conditions and design parameters and analyze the reliability of buried pipeline with corrosion defects according to the probability of failure and a required target safety level. The normalized margin is defined and estimated accordingly. Furthermore, the normalized margin is used to predict the failure probability using the fitting lines between failure probability and normalized margin.

Case studies considering the influence of the time-dependent behaviour of concrete on the serviceability limit state design of composite steel-concrete buildings

2021 ◽  
pp. 137-156
Author(s):  
Alejandro Pérez Caldentey ◽  
John Hewitt ◽  
John van Rooyen ◽  
Graziano Leoni ◽  
Gianluca Ranzi ◽  
...  
Keyword(s):  
Case Studies ◽  
Limit State ◽  
Time Dependent ◽  
Commercial Building ◽  
Time Effects ◽  
Concrete Buildings ◽  
Time Dependent Behaviour ◽  
Dependent Behaviour ◽  
Composite Steel

<p>This chapter presents a number of case studies that deal with the service design of composite steel-concrete buildings associated with the time-dependent behaviour of the concrete. The particular focus of this chapter is to outline key design aspects that need to be accounted for in design and that are influenced by concrete time effects. The first case study provides an overview of the design considerations related to the time-dependent column shortening in typical multi-storey buildings by considering the layout of the Intesa Sanpaolo Headquarters in Turin as reference. The second case study focuses on a composite floor of a commercial building constructed in Australia and it provides an overview of the conceptual design used to select the steel beam framing arrangement to support the composite floor system while accounting for concrete cracking and time effects. The third case study deals with the Quay Quarter Tower that has been designed for the repurposing of an existing 50-year old building in Australia while accounting for the time-dependent interaction between the existing and the new concrete components of the building.</p>

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