scholarly journals A Probabilistic Physics of Failure Approach for Structure Corrosion Reliability Analysis

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Chaoyang Xie ◽  
Hong-Zhong Huang

Corrosion is recognized as one of the most important degradation mechanisms that affect the long-term reliability and integrity of metallic structures. Studying the structural reliability with pitting corrosion damage is useful for risk control and safety operation for the corroded structure. This paper proposed a structure corrosion reliability analysis approach based on the physics-based failure model of pitting corrosion, where the states of pitting growth, pit-to-crack, and cracking propagation are included in failure model. Then different probabilistic analysis methods such as Monte-Carlo Simulation (MCS), First-Order Reliability Method (FORM), Second-Order Reliability Method (SORM), and response surface method are employed to calculate the reliability. At last, an example is presented to demonstrate the capability of the proposed structural reliability model and calculating methods for structural corrosion failure analysis.

Author(s):  
Chaoyang Xie ◽  
Pingfeng Wang ◽  
Zequn Wang ◽  
Hongzhong Huang

Corrosion is one of the most critical failure mechanisms for engineering structures and systems, as corrosion damages grow with the increase of service time, thus diminish system reliability gradually. Despite tremendous efforts, effectively carrying out reliability analysis considering the complicated coupling effects for corrosion remains to be a grand challenge. There is a substantial need to develop sophisticated corrosion reliability models and effective reliability analysis approaches considering corrosion damage growth under coupled effects such as mechanical stresses. This paper presents a physics-of-failure model for pitting corrosion with the coupled effect of corrosion environment and mechanical stresses. With the developed model, corrosion damage growth can be projected and corrosion reliability can be analyzed. To carry out corrosion reliability analysis, the developed pitting corrosion model can be formulated as time-dependent limit state functions considering pit to crack transition, crack growth, and fracture failure mechanics. A newly developed maximum confidence enhancement (MCE)-based sequential sampling approach is then employed to improve the efficiency of corrosion reliability analysis with the time-dependent limit state functions. A case study is presented to illustrate the efficacy of the developed physics-of-failure model for corrosion considering the coupled mechanical stress effects, and the new corrosion reliability analysis methodology.


Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1820
Author(s):  
Mohamed El Amine Ben Seghier ◽  
Behrooz Keshtegar ◽  
Hussam Mahmoud

Reinforced concrete (RC) beams are basic elements used in the construction of various structures and infrastructural systems. When exposed to harsh environmental conditions, the integrity of RC beams could be compromised as a result of various deterioration mechanisms. One of the most common deterioration mechanisms is the formation of different types of corrosion in the steel reinforcements of the beams, which could impact the overall reliability of the beam. Existing classical reliability analysis methods have shown unstable results when used for the assessment of highly nonlinear problems, such as corroded RC beams. To that end, the main purpose of this paper is to explore the use of a structural reliability method for the multi-state assessment of corroded RC beams. To do so, an improved reliability method, namely the three-term conjugate map (TCM) based on the first order reliability method (FORM), is used. The application of the TCM method to identify the multi-state failure of RC beams is validated against various well-known structural reliability-based FORM formulations. The limit state function (LSF) for corroded RC beams is formulated in accordance with two corrosion types, namely uniform and pitting corrosion, and with consideration of brittle fracture due to the pit-to-crack transition probability. The time-dependent reliability analyses conducted in this study are also used to assess the influence of various parameters on the resulting failure probability of the corroded beams. The results show that the nominal bar diameter, corrosion initiation rate, and the external loads have an important influence on the safety of these structures. In addition, the proposed method is shown to outperform other reliability-based FORM formulations in predicting the level of reliability in RC beams.


Mathematics ◽  
2021 ◽  
Vol 9 (13) ◽  
pp. 1544
Author(s):  
Younseok Choi ◽  
Junkeon Ahn ◽  
Daejun Chang

In this study, the structural reliability of plate-stiffened prismatic pressure vessels was analyzed over time. A reliability analysis was performed using a time-dependent structural reliability method based on the response surface method (RSM). The plate-stiffened prismatic pressure vessel had a rectangular cross-section with repeated internal load-bearing structures. For the structural analysis, this repeated structure was modeled as a strip, and a structural reliability analysis was performed to identify changes in the reliability index when general corrosion and pitting corrosion occurred in the outer shell. Pitting corrosion was assumed to be randomly distributed on the outer shell, and the reliability index according to the degree of pit (DOP) and time was analyzed. Analysis results confirmed that the change in the reliability index was larger when pitting corrosion was applied compared with when only general corrosion was applied. Additionally, it was confirmed that above a certain DOP, the reliability index was affected.


2019 ◽  
Vol 66 (5) ◽  
pp. 529-536 ◽  
Author(s):  
Xiaoxiao Liu ◽  
Ming Liu

Purpose Corrosion is one of the common damage mechanisms in many engineering structures such as marine structures, petroleum pipelines, aerospace and nuclear reactor. However, the service performance of metal materials and structures is gradually degenerating with the increase of service life due to the rapid growth of corrosion damages. Thus, the coupled effects for corrosion damage in reliability analysis should be considered urgently. Then, the purpose of this paper is to develop the corrosion damage physical model and the corresponding reliability analysis methods, which consider the coupled effect of corrosion damage. Design/methodology/approach A failure physical model, considering the coupled effect of pitting growth, crack and crack propagation, is presented in this paper. Sequentially, the corrosion reliability with respect to pitting physical damage can be investigated. The presented pitting damage physical model is formulated as time-variant performance limit state functions, which include the crack transition, crack growth and fracture failure mechanics. The first-passage failure criterion is used to construct the corrosion reliability framework, involving in the pitting damage model with the increase of service life. Findings Results demonstrate that the multiplicative dimensional reduction (MDR) method behaves much better than FORM no matter in accuracy or efficiency. The proposed corrosion reliability method is applicable for dealing with the damage failure model of the structural pitting corrosion. Originality/value The MDR method is used to calculate the corrosion reliability index of a given structure with fewer function calls. Finally, an aeronautical metal material is used to demonstrate the efficiency and precision of the proposed corrosion reliability method when the failure physical model considering the coupled effects of mechanical stresses and corrosion environment is adopted.


2018 ◽  
Vol 7 (4.35) ◽  
pp. 210
Author(s):  
Nurul Sa’aadah Sulaiman ◽  
Henry Tan

Maintenance and integrity management of hydrocarbons pipelines face the challenges from uncertainties in the data available. This paper demonstrates a way for pipeline remaining service life prediction that integrates structural reliability analysis, accumulated corrosion knowledge, and inspection data on a sound mathematical foundation. Pipeline defects depth grows with time according to an empirical corrosion power law, and this is checked for leakage and rupture probability. The pipeline operating pressure is checked with the degraded failure pressure given by ASME B31G code for rupture likelihood. As corrosion process evolves with time, Dynamic Bayesian Network (DBN) is employed to model the stochastic corrosion deterioration process. From the results obtained, the proposed DBN model for pipeline reliability is advanced compared with other traditional structural reliability method whereby the updating ability brings in more accurate prediction results of structural reliability. The comparisons show that the DBN model can achieve a realistic result similar to the conventional method, Monte Carlo Simulation with very minor discrepancy.


Author(s):  
Zhi Shu ◽  
Torgeir Moan

This paper deals with the structural reliability analysis (SRA) of ultimate strength of a Capesize bulk carrier in hogging and alternate hold loading condition (AHL). The ultimate strength in hogging and AHL condition is very important for the safety of bulk carriers since the local loads due to internal cargo loads and external sea pressure can reduce the ultimate bending capacity. In the present paper, the characteristic ultimate bending capacity of the subject bulk carrier is investigated by nonlinear finite element (FE) analysis and the characteristic value of the global and local loads are determined in accordance with the Common Structural Rules for bulk carriers (CSR-BC). The uncertainties associated with the loading capacity and load effects are appropriately modelled. The First Order Reliability Method (FORM) is adopted to calculate the annual probability of failure of this bulk carrier in hogging and AHL condition. The effect of heavy weather avoidance on the global and local loads is also evaluated in the SRA. The results show that the local loads have a significant impact on the failure probability of such vessels in the hogging and AHL condition.


Author(s):  
Umberto Alibrandi ◽  
C. G. Koh

This paper presents a novel procedure based on first-order reliability method (FORM) for structural reliability analysis in the presence of random parameters and interval uncertain parameters. In the proposed formulation, the hybrid problem is reduced to standard reliability problems, where the limit state functions are defined only in terms of the random variables. Monte Carlo simulation (MCS) for hybrid reliability analysis (HRA) is presented, and it is shown that it requires a tremendous computational effort; FORM for HRA is more efficient but still demanding. The computational cost is significantly reduced through a simplified procedure, which gives good approximations of the design points, by requiring only three classical FORMs and one interval analysis (IA), developed herein through an optimization procedure. FORM for HRA and its simplified formulation achieve a much improved efficiency than MCS by several orders of magnitude, and it can thus be applied to real-world engineering problems. Representative examples of stochastic dynamic analysis and performance-based engineering are presented.


2015 ◽  
Vol 137 (6) ◽  
Author(s):  
C. Jiang ◽  
W. Zhang ◽  
X. Han ◽  
B. Y. Ni ◽  
L. J. Song

This paper proposed a vine-copula-based structural reliability analysis method which is an effective approach for performing a reliability analysis on complex multidimensional correlation problems. A joint probability distribution function (PDF) among multidimensional random variables was established using a vine copula function, based on which a reliability analysis model was constructed. Two solution algorithms were proposed to solve this reliability analysis model: one was based on Monte Carlo simulation (MCS) and another one was based on the first-order reliability method (FORM). The former method provides a generalized computational method for a reliability analysis based on vine copula functions and can provide so-called “precise solutions”; the latter method has high computational efficiency and can be used to solve actual complex engineering problems. Finally, three numerical examples were provided to verify the effectiveness of the method.


2018 ◽  
Vol 10 (7) ◽  
pp. 168781401878583 ◽  
Author(s):  
Zheng Liu ◽  
Xin Liu

The structural composition of the oil platform is very complicated, and its working environment is harsh, thus conducting a large number of reliability tests is not feasible, and the field tests are also hard to accomplish. So the reliability of the oil platform cannot be analyzed and calculated by the traditional reliability method which needs a lot of test data, and new methods should be studied. In recent years, imprecise probability theory has attracted more and more attention because when unified, it can quantify hybrid uncertainty. Structural reliability analysis on the basis of imprecise probability theory has made remarkable achievements in theoretical aspects, but it is scarcely used in practical engineering domains due to the complexity in the developed methods and the unavailability of suitable or specific modeling steps for applications. In this regard, we propose a unified quantification method for statistical data, fuzzy data, incomplete information, and the like, which can handle the issue of hybrid uncertainties, and then, we construct an improved imprecise structural reliability model aiming at the practical problems by introducing copula function. To verify the existing methodology, we also consider a cantilever beam widely applied in the oil platform here for the structural reliability analysis.


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