A Probabilistic Approach for the Reliability Assessment of Offshore Structure Considering Corrosion and Fatigue

2000 ◽  
Author(s):  
Y.S. Li ◽  
D. Kato ◽  
Y. Ohtani ◽  
Y. Suehiro ◽  
H. Hirayama
Keyword(s):  
Probabilistic Approach ◽  
Reliability Assessment ◽  
Offshore Structure

Robust Reliability Assessment for Offshore Minimum Structures Under Dynamic Loads

2002 ◽  
Author(s):  
Liangbin Xu ◽  
Guoming Chen
Keyword(s):  
Failure Mode ◽  
Failure Modes ◽  
Dynamic Models ◽  
Research Work ◽  
Reliability Assessment ◽  
Dynamic Loads ◽  
Offshore Structure ◽  
Numeric Calculation ◽  
Ice Loads ◽  
Robust Reliability

The offshore minimum structures are widely applied in the development of margin oilfield because of their simplicity in fabrication, low initial investment and fast-track schedule. However, they would suffer large dynamic response under exciting loads such as seismic and ice loads, which might lower their service safety. The paper is focused on robust reliability assessment for the offshore minimum structures under dynamic loads by considering first-exceeding failure mode, fatigue failure mode. The robust reliability of offshore structure is a measure of its resistance to the uncertainties, and it suits very much to the condition that the information and data are scarce. The multi-level fortification for ice-resistant offshore minimum structures is presented in this paper, that is, the structure should not be defective under normal ice condition, repairable under heavy ice condition and not collapse under the heaviest ice condition. A numeric calculation method of robust reliability and several robust reliability dynamic models for offshore minimum structures are put forward in this paper, in which plastic collapse, fatigue, and fracture are dealt with. The interaction between the different failure modes under these loads is also considered in the paper. Based on research work mentioned above, the comprehensive safety assessment for the offshore minimum structures would be more easily realized under dynamic loads such as ice loads, seismic loads. Finally, the example is given.

Simplified Strength Reliability and Integrity Analysis of TTRs

2014 ◽  
Author(s):  
Mir Emad Mousavi ◽  
Sanjeev Upadhye ◽  
Kevin Haverty
Keyword(s):  
Extreme Events ◽  
Structural Reliability ◽  
Probability Distributions ◽  
Probabilistic Approach ◽  
Reliability Assessment ◽  
Cost Effective ◽  
Probability Of Failure ◽  
Annual Probability ◽  
Reliability Methods ◽  
Integrity Analysis

The design of riser systems can be improved if structural reliability methods are used to assess their safety and integrity and confirm that such design meets a target annual probability of failure. TTRs are typically multi–bore assemblies involving several sub-assemblies. The failure of any of the components of a TTR under extreme or service environmental conditions can lead to an immediate failure of the entire assembly and impose a direct risk of damaging the wellheads, conductors, casing and tubing hangers, or other subsea equipment, because they are installed directly on top of the wellhead. However, the actual strength safety of the TTR cannot be examined unless after it is installed and examined under extreme events. Because of the numerous uncertainties associated with the design of TTRs, a probabilistic approach based on structural reliability methods can account for many of those uncertainties and serve as a basis for their reliable and cost-effective design. In turn, a comprehensive reliability assessment of a TTR requires extensive analysis that is considerably more complex and time consuming compared to a conventional deterministic-based analysis. This paper presents a probabilistic-based simplified methodology for the strength reliability assessment of TTR systems. In this method, marginal values on some uncertain model inputs are considered similar to the conventional analysis methods but, some key random variables related to environmental demands and component capacities are considered with their associated probability distributions. As a result, this method can be used to estimate the minimum level of safety of the TTR under extreme events. Additionally, results of the proposed method are discussed for integrity analysis and integrity-based optimal design of the TTR system, which compare the safety of the TTR components and estimate the component Optimality Factors for improving the design integrity and meeting a target minimum annual probability of failure.

scholarly journals Fatigue damage and reliability assessment of subway train bogie frames under operating conditions

2020 ◽  
Vol 12 (1) ◽  
pp. 168781402090359
Author(s):  
Binjie Wang ◽  
Shouguang Sun ◽  
Shuang Ma ◽  
Xi Wang
Keyword(s):  
Fatigue Damage ◽  
Fatigue Cracks ◽  
Probabilistic Approach ◽  
Reliability Assessment ◽  
Elastic Vibration ◽  
Assessment Method ◽  
Operating Conditions ◽  
Fatigue Reliability ◽  
Rail Corrugation ◽  
Subway Train

Fatigue cracks developed on subway train bogie frames before reaching the designed lifetime, which poses great challenges to operational safety. This article presents a structural fatigue reliability assessment method combining both the in-service measurement of dynamic stress and probabilistic approach for lifetime prediction. It was found that curved interval with rail corrugation can induce the elastic vibration and the modal stress on the frame, which caused the accelerated accumulation of the fatigue damage. The predicted failure mileage for the welding joint with 99% reliability was only 340,000 km, which agreed well with the real operation situation.

scholarly journals A Fuzzy Approach for the Kinematic Reliability Assessment of Robotic Manipulators

Robotica ◽  
2021 ◽  
pp. 1-15
Author(s):  
Fabian A. Lara-Molina ◽  
Didier Dumur
Keyword(s):  
Fuzzy Theory ◽  
Probabilistic Approach ◽  
Reliability Assessment ◽  
Robotic Manipulators ◽  
Fuzzy Reliability ◽  
End Effector ◽  
Positioning Errors ◽  
Novel Method ◽  
Joint Clearances ◽  
Failure Possibility

SUMMARY This paper aims at developing a novel method to assess the kinematic reliability of robotic manipulators based on the fuzzy theory. The kinematic reliability quantifies the probability of obtaining positioning errors within acceptable limits. For this purpose, the fuzzy reliability evaluates the effect of the joint clearances on the end-effector position to compute a failure possibility index. As an alternative to the conventional methods reported in the literature, this failure possibility index conveys a novel assessment of the kinematic performance. The numerical results are compared with the well-known probabilistic approach based on the Monte Carlo simulation.

scholarly journals Numerical solution of hard rock disintegration process – part 2

2012 ◽  
Vol 58 (3) ◽  
pp. 39-46
Author(s):  
Karel Frydrýšek
Keyword(s):  
Monte Carlo ◽  
Hard Rock ◽  
Probabilistic Approach ◽  
Reliability Assessment ◽  
Assessment Method ◽  
Deterministic Approach ◽  
Disintegration Process ◽  
Stochastic Inputs ◽  
Simulation Based ◽  
Rock Disintegration

Abstract This paper focuses on a numerical analysis of a hard rock (ore) disintegration process. A bit moves into the ore and subsequently disintegrates it. The disintegration (i.e. fracture of ore) is solved via a deterministic approach (FEM) and a probabilistic approach (FEM in combination with the SBRA - Simulation-Based Reliability Assessment method, i.e. Monte Carlo simulations, stochastic inputs). The ore is disintegrated by deactivating the finite elements satisfying fracture conditions. The results are compared with experiments. The application of the SBRA method is a new and innovative trend in this area. Finally, the probabilistic reliability assessment is mentioned.

Enhanced probabilistic approach for substation reliability assessment

2019 ◽  
Vol 13 (12) ◽  
pp. 2488-2495 ◽  
Author(s):  
Bagen Bagen ◽  
Dange Huang ◽  
Karim Fattal
Keyword(s):  
Probabilistic Approach ◽  
Reliability Assessment

Modelling Issues for Nonlinear Time History Analysis of Offshore Platforms Subjected to Strong Ground Motions

2014 ◽  
Author(s):  
Abe Nezamian ◽  
Patrick M. Morgan
Keyword(s):  
Dynamic Analysis ◽  
Reliability Assessment ◽  
Time History ◽  
Performance Based Design ◽  
Nonlinear Time History Analysis ◽  
Offshore Platforms ◽  
Offshore Structure ◽  
Inelastic Analysis ◽  
Advanced Analysis ◽  
Strong Ground

The response of a platform subjected to a strong ground motion is highly affected by the method of modelling, and special attention should be paid to such advanced analysis. While the potential of dynamic inelastic analysis and performance based design of offshore platforms is recognised in earthquake design and assessment, they have inherent shortcomings. This paper discusses the critical issues and their effects on the obtained results in the application of inelastic dynamic analysis. Areas of possible developments that would render the method more applicable to the prediction of dynamic response, and new developments towards a fully adaptive performance based design are explored. These developments lead to dynamic analysis results that are closer than ever to the true inelastic time-history behavior of the structures. It is concluded that there is great scope for improvements of this powerful technique that would increase confidence in its employment, and encourage its use during design as the primary tool for reliability assessment under seismic loads. The results from a sample project indicated that inelastic time history seismic analysis provides a more realistic assessment of structural behavior and strongly recommended to be implemented for the design and reliability assessment of the fixed offshore structure under extreme seismic event.

scholarly journals Reliability Assessment of Existing Structures

2008 ◽  
Vol 4 (1) ◽  
pp. 149-164
Author(s):  
Marková Jana
Keyword(s):  
Probabilistic Approach ◽  
Reliability Assessment ◽  
Probabilistic Methods ◽  
International Standard ◽  
Existing Structures

Reliability Assessment of Existing Structures The international standard ISO 13822 provides procedures for the reliability assessment of existing structures including the application of probabilistic methods. Probabilistic approach facilitates to decide about new exploitation of existing structures. Application of probabilistic methods for the reliability assessment of existing structures is shown on the example of deteriorated balcony beams.

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