scholarly journals Time-Dependent Reliability Modeling and Analysis Method for Mechanics Based on Convex Process

2015 ◽  
Vol 2015 ◽  
pp. 1-16 ◽  
Author(s):  
Lei Wang ◽  
Xiaojun Wang ◽  
Ruixing Wang ◽  
Xiao Chen
Keyword(s):  
Monte Carlo ◽  
Product Life Cycle ◽  
Process Model ◽  
Limit State ◽  
Simulation Method ◽  
Time Dependent ◽  
Structural Safety ◽  
Time Varying ◽  
Modeling And Analysis ◽  
Convex Process

The objective of the present study is to evaluate the time-dependent reliability for dynamic mechanics with insufficient time-varying uncertainty information. In this paper, the nonprobabilistic convex process model, which contains autocorrelation and cross-correlation, is firstly employed for the quantitative assessment of the time-variant uncertainty in structural performance characteristics. By combination of the set-theory method and the regularization treatment, the time-varying properties of structural limit state are determined and a standard convex process with autocorrelation for describing the limit state is formulated. By virtue of the classical first-passage method in random process theory, a new nonprobabilistic measure index of time-dependent reliability is proposed and its solution strategy is mathematically conducted. Furthermore, the Monte-Carlo simulation method is also discussed to illustrate the feasibility and accuracy of the developed approach. Three engineering cases clearly demonstrate that the proposed method may provide a reasonable and more efficient way to estimate structural safety than Monte-Carlo simulations throughout a product life-cycle.

Local Monte Carlo Simulation for the Reliability Sensitivity Analysis

2011 ◽  
Vol 291-294 ◽  
pp. 2183-2188 ◽  
Author(s):  
Da Wei Li ◽  
Zhen Zhou Lu ◽  
Zhang Chun Tang
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Numerical Technique ◽  
Limit State ◽  
Computational Cost ◽  
Simulation Method ◽  
State Function ◽  
Local Domain ◽  
Monte Carlo Simulation Method ◽  
Reliability Sensitivity

An efficient numerical technique, namely the Local Monte Carlo Simulation method, is presented to assess the reliability sensitivity in this paper. Firstly some samples are obtained by the random sampling, then the local domain with a constant probability content corresponding to each sample point can be defined, finally the conditional reliability and reliability sensitivity corresponding to every local region can be calculated by using linear approximation of the limit state function. The reliability and reliability sensitivity can be estimated by the expectation of all the conditional reliability and reliability sensitivity. Three examples testify the applicability, validity and accuracy of the proposed method. The results computed by the Local Monte Carlo Simulation method and the Monte Carlo method are compared, which demonstrates that, without losing precision, the computational cost by the former method is much less than the later.

Neutron Generation Based Method for Monte Carlo Three-Dimensional Reactor Time-Dependent Simulation

2012 ◽  
Author(s):  
Qi Xu ◽  
Ganglin Yu ◽  
Kan Wang
Keyword(s):  
Monte Carlo ◽  
Dynamic Analysis ◽  
Three Dimensional ◽  
Simulation Method ◽  
Time Dependent ◽  
New Method ◽  
Monte Carlo Code ◽  
Neutron Generation ◽  
Direct Simulation ◽  
Reactor Dynamic

A novel Monte Carlo time-dependent simulation method, named neutron generation based method (NGBM), is proposed for three-dimensional reactor dynamic analysis. Different from the traditional direct simulation method (DSM) based on neutron history, the new method, originating from the process of Monte Carlo criticality calculation, is based on neutron generation. In order to turn the original static calculation into a dynamic one, the time mark and time-dependent flux tally are added, the weight of neutron is adjusted while accumulating the flux estimator and the criteria for ending simulation is set. This new method is of higher computing efficiency than the direct simulation method for super-critical time-dependent situation, because it is able to take the advantage of Monte Carlo criticality calculation to keep the number of neutrons per generation approximately constant while the direct simulation method cannot stop the exponential increase of neutron population. The new method was integrated into RMC (Reactor Monte Carlo code developed by Tsinghua University). A numerical experiment was performed. The results demonstrate the feasibility and accuracy of the neutron generation based method for reactor dynamic analysis. The relative deviation of the time-dependent neutron flux tells that the accuracy of the neutron generation based method is enough for routine reactor safety analysis. And the experiment also shows the high efficiency of this method for super-critical reactor systems, since in the experiment, RMC runs nearly 7 times faster than MCNP which uses the direct simulation method.

scholarly journals Overview of Calculation Methods of Structural Time-Dependent Reliability

2022 ◽  
Vol 2148 (1) ◽  
pp. 012063
Author(s):  
Lisheng Luo ◽  
Xinran Xie ◽  
Yongqiang Zhang ◽  
Wenyuan He
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Simulation Method ◽  
Safety Performance ◽  
Time Dependent ◽  
Structural Performance ◽  
Monte Carlo Simulation Method ◽  
Calculation Methods ◽  
New Methods ◽  
Reliability Method

Abstract Under the action of natural erosion, the strength, durability and other safety performance of structures and elements gradually decrease with time, which has a great impact. To solve the above problem, a series of time-dependent reliability analysis methods were proposed. Based on different structural performance functions, this paper analyzes and discusses different time-dependent reliability theories, including outcrossing-based reliability method, Monte Carlo simulation method, extremum method and other new methods proposed in recent years, which provides reference for later research.

scholarly journals ANÁLISE DE CONFIABILIDADE ESTRUTURAL DE PROBLEMAS BASEADOS NA MECÂNICA DOS SÓLIDOS

2016 ◽  
Vol 12 (2) ◽  
Author(s):  
Vinícius Favaretto Defiltro ◽  
Wellison José Santana Gomes
Keyword(s):  
Monte Carlo ◽  
Reliability Analysis ◽  
Structural Reliability ◽  
Solid Mechanics ◽  
Structural Model ◽  
Simulation Method ◽  
Probability Of Failure ◽  
Structural Safety ◽  
Structural Element ◽  
Structural Problems

RESUMO: A Mecânica dos Sólidos, a partir de hipóteses simplificadoras, fornece modelos de cálculo que podem ser aplicados a vários problemas estruturais e estabelece as bases e o entendimento para o desenvolvimento de teorias e a construção de modelos mais complexos. Entretanto, dentro deste contexto, é comum desprezar as incertezas inerentes às propriedades dos materiais envolvidos, às condições de contorno e à geometria do problema. Neste artigo, ferramentas da Teoria da Confiabilidade Estrutural são aplicadas a problemas estruturais baseados na Mecânica dos Sólidos no intuito de analisá-los considerando algumas das incertezas envolvidas. Para isso, o método de Simulação de Monte Carlo é empregado na análise de confiabilidade de duas vigas. No estudo da primeira estrutura, busca-se investigar a influência da correlação entre variáveis aleatórias na probabilidade de falha do elemento estrutural. Na segunda estrutura, analisa-se o efeito da utilização de materiais com diferentes comportamentos (frágeis ou dúcteis) e, consequentemente, diferentes critérios de ruptura, sobre a probabilidade de falha estimada. Verifica-se que as análises de confiabilidade estrutural podem fornecer muitas informações que estão fora do escopo das soluções determinísticas. Tais informações permitem uma avaliação mais precisa da segurança estrutural e podem também levar a um melhor entendimento do modelo estrutural em questão. ABSTRACT: The Solid Mechanics, from simplifying assumptions, provides calculation models that can be applied to various structural problems and establishes the foundation and the understanding for the development of theories and the construction of more complex models. However, within this context, it is common to despise the uncertainties inherent to the properties of the materials involved, the boundary conditions and the geometry of the problem. In this article, Structural Reliability Theory tools are applied to structural problems based on Solid Mechanics in order to analyze them considering some of the uncertainties involved. For this, the Monte Carlo simulation method is used in the reliability analysis of two beams. In the first structure, study seeks to investigate the influence of correlation between random variables on the probability of failure of the structural element. In the second one, the effect of using materials with different behavior (ductile or brittle) and, consequently, different rupture criteria on the estimated probability of failure is analyzed. Structural reliability analysis can provide information which usually is outside the scope of deterministic solutions. Such information enables a more accurate assessment of structural safety and may lead to a better understanding of the structural model in question.

Structural reliability of corroded pipeline using the so-called Separable Monte Carlo method

2018 ◽  
Vol 53 (8) ◽  
pp. 730-737 ◽  
Author(s):  
Mohamed el Amine Ben Seghier ◽  
Mourad Bettayeb ◽  
José Correia ◽  
Abílio De Jesus ◽  
Rui Calçada
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Structural Reliability ◽  
Computational Cost ◽  
Simulation Method ◽  
Computational Method ◽  
Time Dependent ◽  
Monte Carlo Simulation Method ◽  
Corrosion Defects ◽  
Separable Monte Carlo

The evaluation of the failure probability of corroded pipelines is an important calculation to quantify the risk assessment and integrity of pipelines. Traditional Monte Carlo simulation method has been widely used to solve this type of problems, where it generates a very large number of simulations and takes longer time in computing. In this study, enhanced computational method called Separable Monte Carlo is employed to evaluate the time-dependent reliability of pipeline segments containing active corrosion defects, where a practical example was used. The results show that the Separable Monte Carlo simulation method not only minimizes the computational cost strongly but also improves the calculation precision.

scholarly journals Non-deterministic Approach for Reliability Evaluation of Steel Beam

2019 ◽  
Vol 26 (1) ◽  
pp. 121-141 ◽  
Author(s):  
Hawraa Qasim Jebur ◽  
Salah R Al-Zaidee
Keyword(s):  
Monte Carlo ◽  
Limit State ◽  
Simulation Method ◽  
Statistical Characteristics ◽  
Steel Beam ◽  
State Function ◽  
Load Effect ◽  
First Order ◽  
Two Samples ◽  
Reliability Method

This paper aims to evaluate the reliability analysis for steel beam which represented by the probability of Failure and reliability index. Monte Carlo Simulation Method (MCSM) and First Order Reliability Method (FORM) will be used to achieve this issue. These methods need two samples for each behavior that want to study; the first sample for resistance (carrying capacity R), and second for load effect (Q) which are parameters for a limit state function. Monte Carlo method has been adopted to generate these samples dependent on the randomness and uncertainties in variables. The variables that consider are beam cross-section dimensions, material property, beam length, yield stress, and applied loads. Matlab software has been adopted to generate these pseudo-random variables dependent on its statistical characteristics such as coefficient of variance and probability density function that gathered from a review of literatures.

Comparison of steel frames with RWS and WFP beam-to-column connections through seismic fragility analysis

2020 ◽  
pp. 136943322097728
Author(s):  
Haoran Yu ◽  
Weibin Li
Keyword(s):  
Limit State ◽  
Pushover Analysis ◽  
Steel Frames ◽  
Fragility Analysis ◽  
Structural Safety ◽  
Seismic Fragility ◽  
Fe Modelling ◽  
Collapse Resistance ◽  
Seismic Collapse ◽  
Probabilistic Seismic Demand

Reduced web section (RWS) connections and welded flange plate (WFP) connections can both effectively improve the seismic performance of a structure by moving plastic hinges to a predetermined location away from the column face. In this paper, two kinds of steel frames—with RWS connections and WFP connections—as well as different frames with welded unreinforced flange connections were studied through seismic fragility analysis. The numerical simulation was conducted by using multiscale FE modelling. Based on the incremental dynamic analysis and pushover analysis methods, probabilistic seismic demand analysis and seismic capability analysis were carried out, respectively. Finally, combined with the above analysis results, probabilistic seismic fragility analysis was conducted on the frame models. The results showed that the RWS connection and WFP connection (without double plates) have little influence on reducing the maximum inter-storey drift ratio under earthquake action. RWS connections slightly reduce the seismic capability in non-collapse stages and improve the seismic collapse resistance of a structure, which exhibits good structural ductility. WFP connections can comprehensively improve the seismic capability of a structure, but the seismic collapse resistance is worse than that of RWS connections when the structure has a large number of storeys. The frame with WFP connections has a lower failure probability at every seismic limit state, while the frame with RWS connections sacrifices some of its structural safety in non-collapse stages to reduce the collapse probability.

scholarly journals Modeling and Analysis of a Generic Internal Cargo Airdrop System for a Tandem Helicopter

2021 ◽  
Vol 11 (11) ◽  
pp. 5109
Author(s):  
Guozhi Li ◽  
Yihua Cao ◽  
Maosheng Wang
Keyword(s):  
Nonlinear Dynamics ◽  
Flight Dynamics ◽  
Simulation Method ◽  
Rotational Dynamics ◽  
Discretization Method ◽  
Modeling And Analysis ◽  
Flight Velocity ◽  
Vector Mechanics ◽  
Good Attitude

This article describes the results of modeling and analysis of a generic internal cargo system using a discretization method of the vector mechanics. The model can be easily incorporated into a tandem helicopter model and is intended for use of simulation and investigating the problems of flight dynamics, control, etc., both in flight operation loading a cargo and flight operation in the process of airdrops. The model is derived by considering the main descriptions of the cargo, including the linear and rotational dynamics, the kinematics, and the forces and moments acting on the helicopter. A simulation method embedded with a numerical trim algorithm is developed for the complete coupling helicopter/cargo nonlinear dynamics system. The simulation application of the model is illustrated, including the case of flight operation loading a cargo by considering three mass configurations of 3000, 4500, and 6000 kg, and the case of flight operation in the process of airdrops at velocities of 0, 40, 80, 120, and 160 knots. Stabilities of the helicopter in the process of airdrops are also analyzed. The major conclusions drawn are: (i) the tandem helicopter has a good attitude maintaining ability in the whole flight velocity envelope when it conducts a flight operation loading a cargo; (ii) in the process of airdrops, the increase in flight velocity will constantly decrease the helicopter pitching attitude and increases the total airdrop time and decreases the backward moving velocity of the cargo, and helicopter flying at a velocity between 80 and 120 knots might be acceptable; (iii) the stabilities of both the longitudinal and lateral periodic modes are continuing to decrease during the backward movement of the cargo.

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