scholarly journals Estimation of High Structural Reliability Involving Nonlinear Dependencies Based on Linear Correlations

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Liulin Kong ◽  
Heng Li ◽  
Bo Zhang ◽  
Hanbin Luo
Keyword(s):  
Material Properties ◽  
Structural Reliability ◽  
High Reliability ◽  
Reliability Evaluation ◽  
Frame Structure ◽  
Gaussian Copula ◽  
Limited Data ◽  
Non Gaussian ◽  
Vine Copula ◽  
Linear Correlations

Stochastic nonlinear dependencies have been reported extensively between different uncertain parameters or in their time or spatial variance. However, the description of dependency is commonly not provided except a linear correlation. The structural reliability incorporating nonlinear dependencies thus needs to be addressed based on the linear correlations. This paper first demonstrates the capture of nonlinear dependency by fitting various bivariate non-Gaussian copulas to limited data samples of structural material properties. The vine copula model is used to enable a flexible modeling of multiple nonlinear dependencies by mapping the linear correlations into the non-Gaussian copula parameters. A sequential search strategy is applied to achieve the estimate of numerous copula parameters, and a simplified algorithm is further designed for reliability involving stationary stochastic processes. The subset simulation is then adopted to efficiently generate random variables from the corresponding distribution for high reliability evaluation. Two examples including a frame structure with different stochastic material properties and a cantilever beam with spatially variable stochastic modulus are investigated to discuss the possible effects of nonlinear dependency on structural reliability. Since the dependency can be determined qualitatively from limited data, the proposed method provides a feasible way for reliability evaluation with prescriptions on correlated stochastic parameters.

An intelligent system for vessels structural reliability evaluation

2016 ◽  
pp. 1891-1898
Author(s):  
A.L. Michala ◽  
N. Barltrop ◽  
P. Amirafshari ◽  
I. Lazakis ◽  
G. Theotokatos
Keyword(s):  
Structural Reliability ◽  
Intelligent System ◽  
Reliability Evaluation

scholarly journals Improvements of Rackwitz–Fiessler Method for Correlated Structural Reliability Analysis

2019 ◽  
Vol 17 (06) ◽  
pp. 1950077 ◽  
Author(s):  
Sheng-Tong Zhou ◽  
Qian Xiao ◽  
Jian-Min Zhou ◽  
Hong-Guang Li
Keyword(s):  
Structural Reliability ◽  
Pearson Correlation ◽  
Computational Cost ◽  
Transformation Process ◽  
Point Of View ◽  
Gaussian Copula ◽  
Normal Space ◽  
Copula Theory ◽  
Geometric Point ◽  
Nataf Transformation

Rackwitz–Fiessler (RF) method is well accepted as an efficient way to solve the uncorrelated non-Normal reliability problems by transforming original non-Normal variables into equivalent Normal variables based on the equivalent Normal conditions. However, this traditional RF method is often abandoned when correlated reliability problems are involved, because the point-by-point implementation property of equivalent Normal conditions makes the RF method hard to clearly describe the correlations of transformed variables. To this end, some improvements on the traditional RF method are presented from the isoprobabilistic transformation and copula theory viewpoints. First of all, the forward transformation process of RF method from the original space to the standard Normal space is interpreted as the isoprobabilistic transformation from the geometric point of view. This viewpoint makes us reasonably describe the stochastic dependence of transformed variables same as that in Nataf transformation (NATAF). Thus, a corresponding enhanced RF (EnRF) method is proposed to deal with the correlated reliability problems described by Pearson linear correlation. Further, we uncover the implicit Gaussian copula hypothesis of RF method according to the invariant theorem of copula and the strictly increasing isoprobabilistic transformation. Meanwhile, based on the copula-only rank correlations such as the Spearman and Kendall correlations, two improved RF (IRF) methods are introduced to overcome the potential pitfalls of Pearson correlation in EnRF. Later, taking NATAF as a reference, the computational cost and efficiency of above three proposed RF methods are also discussed in Hasofer–Lind reliability algorithm. Finally, four illustrative structure reliability examples are demonstrated to validate the availability and advantages of the new proposed RF methods.

Structural Reliability Analysis With Cross Entropy and Low Discrepancy Sampling Methods

2011 ◽  
Author(s):  
K. Pugazhendhi ◽  
A. K. Dhingra
Keyword(s):  
Monte Carlo ◽  
Importance Sampling ◽  
Structural Reliability ◽  
Sampling Methods ◽  
Reliability Evaluation ◽  
Cross Entropy ◽  
Sampling Density ◽  
Quasi Monte Carlo ◽  
Importance Sampling Techniques ◽  
Optimum Sampling

In recent years quasi Monte-Carlo (QMC) techniques are gaining more popularity for reliability evaluation because of their increased accuracy over traditional Monte-Carlo simulation. A QMC technique like Low Discrepancy Sequence (LDS) combined with importance sampling is shown to be more accurate and robust in the past for the evaluation of structural reliability. However, one of the challenges in using importance sampling techniques to evaluate the structural reliability is to identify the optimum sampling density. In this article, a novel technique based on a combination of cross entropy and low discrepancy sampling methods is used for the evaluation of structural reliability. The proposed technique does not require an apriori knowledge of Most Probable Point of failure (MPP), and succeeds in adaptively identifying the optimum sampling density for the structural reliability evaluation. Several benchmark examples verify that the proposed method is as accurate as the quasi Monte-Carlo technique using low discrepancy sequence with the added advantage of being able to accomplish this without a knowledge of the MPP.

Reliability Evaluation of CSP Using New Flip-Chip Bonding Technology: Both-Sided CSP and Single-Sided CSP

2002 ◽  
Author(s):  
Hideo Koguchi ◽  
Nipon Taweejun ◽  
Kazuto Nishida ◽  
Chie Sasaki
Keyword(s):  
Finite Element Method ◽  
Cross Section ◽  
Flip Chip ◽  
High Reliability ◽  
Reliability Evaluation ◽  
Thickness Direction ◽  
Material Parameters ◽  
Conductive Film ◽  
Chip Size ◽  
Bonding Technology

Chip-size packaging (CSP) attracts largely attentions due to its lighter, thinner and smaller size. In this study, the deformations and the stresses in the CSP fabricated by non-conductive film stud-bump direct interconnection (NSD) were analyzed. The reliability evaluation of single-sided CSP and both-sided CSP were investigated for heat cycles. The material parameters, i.e. stresses, strains and deformations, for achieving a high reliability of CSP were investigated using a finite element method and experiment. The dependency of the life in single-sided CSP and both-sided CSP on the thicknesses of IC and substrate could be expressed using a normal stress in the thickness direction and shear stress in the vertical cross section, respectively.

A Practical Approach to Pipeline System Materials Verification

2012 ◽  
Author(s):  
Andrew R. Lutz ◽  
Thomas A. Bubenik
Keyword(s):  
Material Properties ◽  
High Reliability ◽  
Pipeline System ◽  
Document Type ◽  
Document Structure ◽  
Related Information ◽  
Property Data ◽  
Daunting Task ◽  
Digital Document ◽  
Material Information

The Pipeline and Hazardous Material Safety Administration (PHSMA) has increased emphasis on records that are “traceable, verifiable, and complete.” Organizing records into a document structure that is traceable, verifiable, and complete can be a daunting task. Through work with operators, Det Norske Veritas (U.S.A.) Inc. (DNV) identified a methodology to efficiently search and organize material property data and records into a structure that is fit for regulatory audit. The methodology consists of four steps: (1) Search/Organize Documentation. (2) Digitally Capture Paper Documents. (3) Determine Document Precedence. (4) Create a Reference-able Listing. The first step reviews all files and records and identifies records that are pertinent to properties verification. The search is conducted at an operator’s office(s) by a team of personnel familiar with pipeline construction and maintenance documentation. Once records have been identified, they are digitally captured (scanned) making them easy to reference. This requires a set of metadata and unique name for each document. The metadata consists of project number, document type (maintenance form, drawing, etc…), pipeline name, and information location. Document precedence is used to identify documents most likely to contain correct material information. Document precedence is determined with operator employees that can identify document(s) that have been historically given high reliability. Finally, a listing tabulates material properties along with the unique document name(s) for the specific records. The listing contains pipe (by segment or joint), fittings (valves, prefabricated elbows, etc…), and other components that may affect Maximum (Allowable) Operating Pressures. Typically the listing uses linear pipeline stationing as the main reference. Implementation of the methodology yields a listing of material properties specifically linked to a digital document database — i.e., a records system that is “traceable, verifiable, and complete.” In addition to material properties, this methodology has also been applied to risk-related information (e.g. cathodic protection, crossings, coating information, etc…). The listing can then be used to identify any information gaps and potentially prioritize them based on reliability.

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