scholarly journals Toward the Effect of Dependent Distribution Parameters on Reliability Prediction

2018 ◽  
Vol 18 (2) ◽  
Author(s):  
Yao Cheng ◽  
Xiaoping Du
Keyword(s):  
Distribution Parameter ◽  
Reliability Prediction ◽  
Interval Parameter ◽  
Analysis And Design ◽  
Simulation And Optimization ◽  
Reliability Bounds ◽  
Distribution Parameters ◽  
Reliability Methods ◽  
Independent Distribution ◽  
Interval Distribution

Random variables are commonly encountered in engineering applications, and their distributions are required for analysis and design, especially for reliability prediction during the design process. Distribution parameters are usually estimated using samples. In many applications, samples are in the form of intervals, and the estimated distribution parameters will also be in intervals. Traditional reliability methodologies assume independent interval distribution parameters, but as shown in this study, the parameters are actually dependent since they are estimated from the same set of samples. This study investigates the effect of the dependence of distribution parameters on the accuracy of reliability analysis results. The major approach is numerical simulation and optimization. This study demonstrates that the independent distribution parameter assumption makes the estimated reliability bounds wider than the true bounds. The reason is that the actual combination of the distribution parameters may not include the entire box-type domain assumed by the independent interval parameter assumption. The results of this study not only reveal the cause of the imprecision of the independent distribution parameter assumption, but also demonstrate a need of developing new reliability methods to accommodate dependent distribution parameters.

Effect of Dependent Interval Distribution Parameters on Reliability Prediction

2017 ◽  
Author(s):  
Yao Cheng ◽  
Xiaoping Du
Keyword(s):  
Reliability Analysis ◽  
Limit State ◽  
Distribution Parameter ◽  
State Function ◽  
Simulation And Optimization ◽  
Distribution Parameters ◽  
Reliability Methods ◽  
Input Variables ◽  
Independent Distribution ◽  
Interval Distribution

Distributions of input variables of a limit-state function are required for reliability analysis. The distribution parameters are commonly estimated using samples. If some of the samples are in the form of intervals, the estimated distribution parameters will also be given in intervals. Traditional reliability methodologies assume that interval distribution parameters are independent, but as shown in this study, the parameters are actually dependent since they are estimated from the same set of samples. This study investigates the effect of the dependence of distribution parameters on the accuracy of reliability analysis results. The major approach is numerical simulation and optimization. This study indicates that the independent distribution parameter assumption makes the estimated reliability bounds wider than the true bounds due to interval samples. The reason is that the actual combination of the distribution parameters may not include the entire box-type domain assumed by the independent interval parameter assumption. The results of this study not only reveal the cause of the inaccuracy of the independent distribution parameter assumption, but also demonstrate a need of developing new reliability methods to accommodate dependent distribution parameters.

System Reliability Analysis With Dependent Component Failures During Early Design Stage—A Feasibility Study

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Yao Cheng ◽  
Xiaoping Du
Keyword(s):  
System Reliability ◽  
Reliability Prediction ◽  
Design Stage ◽  
Early Design ◽  
Early Design Stage ◽  
Design Concepts ◽  
Reliability Bounds ◽  
Lack Of Information ◽  
Dependent Component ◽  
Component Failures

It is desirable to predict product reliability accurately in the early design stage, but the lack of information usually leads to the use of independent component failure assumption. This assumption makes the system reliability prediction much easier, but may produce large errors since component failures are usually dependent after the components are put into use within a mechanical system. The bounds of the system reliability can be estimated, but are usually wide. The wide reliability bounds make it difficult to make decisions in evaluating and selecting design concepts, during the early design stage. This work demonstrates the feasibility of considering dependent component failures during the early design stage with a new methodology that makes the system reliability bounds much narrower. The following situation is addressed: the reliability of each component and the distribution of its load are known, but the dependence between component failures is unknown. With a physics-based approach, an optimization model is established so that narrow bounds of the system reliability can be generated. Three examples demonstrate that it is possible to produce narrower system reliability bounds than the traditional reliability bounds, thereby better assisting decision making during the early design stage.

scholarly journals COMPUTING IN-SERVICE AIRCRAFT RELIABILITY

2009 ◽  
Vol 16 (02) ◽  
pp. 91-116 ◽  
Author(s):  
LAURENT SAINTIS ◽  
EMMANUEL HUGUES ◽  
CHRISTIAN BES ◽  
MARCEL MONGEAU
Keyword(s):  
Real World ◽  
Efficient Algorithm ◽  
Design Stage ◽  
Mathematical Framework ◽  
Preliminary Design ◽  
Timing Constraints ◽  
Service Interruption ◽  
Reliability Bounds ◽  
Preliminary Design Stage ◽  
Reliability Methods

This paper deals with the modeling and computation of in-service aircraft reliability at the preliminary design stage. This problem is crucial for aircraft designers because it enables them to evaluate in-service interruption rates, in view of designing the system and of optimizing aircraft support. In the context of a sequence of flight cycles, standard reliability methods are not computationally conceivable with respect to industrial timing constraints. In this paper, first we construct the mathematical framework of in-service aircraft reliability. Second, we use this model in order to demonstrate recursive formulae linking the probabilities of the main failure events. Third, from these analytic developments, we derive relevent reliability bounds. We use these bounds to design an efficient algorithm to estimate operational interruption rate indicators. Finally, we show the usefulness of our approach on real-world cases provided by Airbus.

scholarly journals Flight Safety Challenges and Assessment

10.12737/4837 ◽  
2014 ◽  
Vol 3 (4) ◽  
pp. 28-33
Author(s):  
Попов ◽  
Yuriy Popov
Keyword(s):  
Weibull Distribution ◽  
Transport System ◽  
Time Dependent ◽  
Air Transport ◽  
Flight Safety ◽  
Interval Parameter ◽  
Dependent Behavior ◽  
Typical Time ◽  
Distribution Parameters ◽  
Safety Estimation

The article analyses air transport system and presents reasons of air incidents and flight safety estimation score. Dependence of air accidents amount per 100 000 flight hours is compared to typical time dependent behavior of failure rate and divided into three intervals. The intervals are analyzed and the reasons of change of parameter score are submitted. Statistical characteristics of the number of accidents per interval parameter are provided. Parameter of air accidents per year matches the Weibull distribution; estimations of Weibull distribution parameters are submitted. Probability of accidents is calculated for each interval; obtained results are analyzed. Ways for furthering flight safety and air transport system are suggested.

scholarly journals Decomposition analysis and peak stagger design for Crank-triangular linkage-elbow mechanism of mechanical servo presses

2021 ◽  
Vol 22 ◽  
pp. 43
Author(s):  
Yousong Sun ◽  
Jianguo Hu ◽  
Liangmo Wei ◽  
Yongqi Chen
Keyword(s):  
Design Method ◽  
Decomposition Analysis ◽  
Structural Parameter ◽  
Preliminary Design ◽  
Working Mechanism ◽  
Mechanical Advantage ◽  
Analysis And Design ◽  
Simulation And Optimization ◽  
Bottom Dead Center ◽  
Working Performance

High mechanical advantage as well as low and steady slide speed within the working stroke Sn are the fundamental requirements for the working mechanism of servo-mechanical press. Currently, the Crank-Triangular Linkage-Elbow (CTLE) mechanism has attracted more and more attention from researchers and manufacturers of servo presses. This paper presents a new analysis and design method of CTLE. The mechanism is decomposed into two sub-units: crank and triangular-linkage elbow, followed by the kinematic and force analysis of each sub-unit. The influences of each structural parameter on the working performance are obtained and can be used as the basis for preliminary design. Through the offset design, the mechanical advantage peaks of the two units, MA1max and MA2max, do not occur at the same time: MA1max is located near Sn, while MA2max is just at BDC (Bottom Dead Center). Because the mechanical advantage of the whole mechanism is the product of the two subunits, the designed mechanism can obtain high and steady mechanical advantage together with low and steady slide speed within Sn. After preliminary design, the scheme can be further modified by numerical simulation and optimization. Hence the design efficiency can be improved.

Reliability Prediction of Gear Transmissions

2007 ◽  
Author(s):  
Victor E. Starzhinsky ◽  
Yuri L. Soliterman ◽  
Arcadi M. Goman
Keyword(s):  
Plastic Deformation ◽  
Failure Modes ◽  
Contact Fatigue ◽  
Reliability Prediction ◽  
Stress Distributions ◽  
Short Term ◽  
Permissible Stress ◽  
Distribution Parameters ◽  
Prolonged Service ◽  
Transmission Gear

Service life of any individual transmission gears is known to represent a stochastic value. The methods of predicting gearing reliability as a relation of the acting and permissible stress distributions are described. The probability of transmission gear non-failure service is considered with most characteristic failure modes such as the tooth breakage and plastic deformation of the tooth working surfaces under a short-term maximal dynamic loading and the bending and contact fatigue under prolonged service loads. The employment of different statistical distribution parameters for gear reliability prediction is considered. A practical example of gearing reliability prediction is given.

Simulation and Optimization of an Actuator

2015 ◽  
Vol 1099 ◽  
pp. 110-119
Author(s):  
Norelislam El Hami ◽  
Mhamed Itmi ◽  
A. El Hami
Keyword(s):  
Particle Swarm Optimization ◽  
Simulated Annealing ◽  
Numerical Models ◽  
Limit State ◽  
Particle Swarm ◽  
Rectangular Plates ◽  
Swarm Optimization ◽  
Simulation And Optimization ◽  
Reliability Methods ◽  
State Functions

This paper presents a new methodology for the Reliability Based Particle Swarm Optimization with Simulated Annealing. The reliability analysis procedure couple traditional and modified first and second order reliability methods, in rectangular plates modelled by an Assumed Modes approach. Both reliability methods are applicable to the implicit limit state functions through numerical models, like those based on the Assumed Mode Method. In modified approaches, the algorithms are based on heuristic optimization methods such as Particle Swarm Optimization and Simulated Annealing Optimization. Numerical applications in static, dynamic and stability problems are used to illustrate the applicability and effectiveness of proposed methodology. The results of example show that the predicted reliability levels are accurate to evaluate simultaneously various implicit limit state functions with respect to static, dynamic and stability criterions.

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