Bayesian Updating in the Reliability Assessment of Maintained Floating Structures

2002 ◽  
Vol 124 (3) ◽  
pp. 139-145 ◽  
Author(s):  
Y. Garbatov ◽  
C. Guedes Soares
Keyword(s):  
Crack Initiation ◽  
Crack Growth ◽  
Bayesian Approach ◽  
Crack Detection ◽  
Probability Distributions ◽  
Reliability Assessment ◽  
Bayesian Updating ◽  
Time Dependent ◽  
Fatigue Reliability ◽  
Floating Structures

The present paper adopts a Bayesian approach to update some of the parameters of the probability distributions governing the reliability assessment of maintained floating structures. It is based on a time dependent fatigue reliability formulation presented earlier but the description of the time to crack initiation, crack growth law and probability of crack detection are updated using the information from the inspections. Its performance is demonstrated with a simulated example.

A Review of Crack Detection In-Line Inspection Case Studies

2010 ◽  
Author(s):  
Neil Bates ◽  
David Lee ◽  
Clifford Maier
Keyword(s):  
Crack Growth ◽  
Case Studies ◽  
Crack Detection ◽  
Growth Parameters ◽  
Probability Distributions ◽  
Low Frequency ◽  
Probability Of Failure ◽  
Probability Of Detection ◽  
Inspection Data

This paper describes case studies involving crack detection in-line inspections and fitness for service assessments that were performed based on the inspection data. The assessments were used to evaluate the immediate integrity of the pipeline based on the reported features and the long-term integrity of the pipeline based on excavation data and probabilistic SCC and fatigue crack growth simulations. Two different case studies are analyzed, which illustrate how the data from an ultrasonic crack tool inspection was used to assess threats such as low frequency electrical resistance weld seam defects and stress corrosion cracking. Specific issues, such as probability of detection/identification and the length/depth accuracy of the tool, were evaluated to determine the suitability of the tool to accurately classify and size different types of defects. The long term assessment is based on the Monte Carlo method [1], where the material properties, pipeline details, crack growth parameters, and feature dimensions are randomly selected from certain specified probability distributions to determine the probability of failure versus time for the pipeline segment. The distributions of unreported crack-related features from the excavation program are used to distribute unreported features along the pipeline. Simulated crack growth by fatigue, SCC, or a combination of the two is performed until failure by either leak or rupture is predicted. The probability of failure calculation is performed through a number of crack growth simulations for each of the reported and unreported features and tallying their respective remaining lives. The results of the probabilistic analysis were used to determine the most effective and economical means of remediation by identifying areas or crack mechanisms that contribute most to the probability of failure.

Time-variant fatigue reliability evaluation of riveted lap joint under stationary random loading

2020 ◽  
Vol 234 (4) ◽  
pp. 567-578
Author(s):  
Shan Jiang ◽  
Yan-Fu Li
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Closure ◽  
Growth Model ◽  
Reliability Assessment ◽  
Fatigue Reliability ◽  
Lap Joint ◽  
Random Loading ◽  
Crack Growth Model

This article focuses on the time-variant reliability assessment of riveted lap joint structure subjected to fatigue. A physics-based fatigue crack growth model that can take the crack closure into account is derived to calculate the crack length at different time under arbitrary loading. In addition, several uncertainties are quantified, including the material, initial crack size, and loading condition. The stationary random loading is a common service environment in practice, in which the stress range and stress ratio vary with constant statistical characteristics (the mean and standard deviation). The time-variant fatigue reliability of riveted lap joint under stationary random loading is assessed by introducing the outcrossing concept. The experimental data of 2024-T3 aluminum alloy riveted lap joint under constant amplitude loading are used to validate the physics-based fatigue crack growth model. It is verified that this proposed model can predict the fatigue life probability distribution with a reasonable accuracy. In addition, the simulation of riveted lap joint under stationary random loading is performed. The time-variant fatigue reliability is evaluated. The results with or without considering crack closures are also compared. It is noted that the results from the time-variant fatigue reliability assessment considering crack closure has higher reliability level.

Detection of Crack Initiation Based on Repeat In-Line Inspection

2016 ◽  
Author(s):  
Michael Palmer ◽  
Christopher Davies ◽  
Markus Ginten ◽  
Roland Palmer-Jones
Keyword(s):  
Crack Initiation ◽  
Crack Growth ◽  
Crack Detection ◽  
Feature Matching ◽  
Data Sets ◽  
Gas Pipelines ◽  
Electromagnetic Acoustic Transducer ◽  
As Stress ◽  
Reliable Solution ◽  
Inspection Data

As Stress Corrosion Cracking (SCC) and other cracking related issues become a more recognised hazard or threat that can be monitored by in-line inspection (ILI), there have been high expectations for the pipeline inspection industry to produce a reliable solution for identifying and sizing cracks. The current leading ILI technologies provided for pipeline crack detection are Ultrasonic (UT) and Electromagnetic Acoustic Transducer (EMAT). The introduction of EMAT In-Line Inspection technologies has provided a proven solution for crack detection that can be used in gas pipelines without having to introduce a liquid couplant into the pipeline. With the development of these technologies worldwide pipeline regulators are putting more pressure on the industry to monitor integrity issues relating to cracking. For example USA pipeline operators are required by the Office of Pipeline Safety to inspect and assess their pipelines that operate within high consequence areas for integrity issues, such as SCC, and repair or replace affected pipe. The inspection options for this include the use of Inline inspection tools — “smart pigs”. These regulations in combination with the majority of pipeline incidents relating to SCC occurring in gas pipelines have led to a significant increase in the use of EMAT ILI technology in recent years. With repeat EMAT ILIs now being conducted on some pipelines there is the option to compare data sets to identify any changes between inspections. Due to the complexities of the EMAT measurement principle and the volumes of data recorded, the process of directly comparing raw signal data from two runs is still in its infancy and cannot currently be used to confirm or discount evidence of crack growth, such as the industry has seen with estimation of corrosion growth based on Magnetic Flux Leakage (MFL) technology signal comparison. However the comparison of EMAT data sets can aid the identification of crack initiation. This technical paper presents a method for identifying the initiation of crack growth (the development of newly detectable cracks) based on repeat EMAT ILI, using feature matching and comparison of raw EMAT inspection data. The implications for integrity management of the identification of newly detectable SCC are discussed, and possible future improvements are outlined. The paper includes a case study that illustrates some of the issues.

scholarly journals Compatibility of S-N and crack growth curves in the fatigue reliability assessment of a welded steel joint

2017 ◽  
Vol 5 ◽  
pp. 959-966
Author(s):  
Bahman Hashemi ◽  
Johan Maljaars ◽  
Davide Leonetti ◽  
H.H (Bert) Snijder
Keyword(s):  
Crack Growth ◽  
Reliability Assessment ◽  
Growth Curves ◽  
Fatigue Reliability ◽  
Welded Steel ◽  
Steel Joint

Crack Detection and Monitoring Crack Growth in Fastener Holes Using the DMI Optical SR-2 Strain Measurement Technology

2007 ◽  
Author(s):  
William F. Ranson ◽  
Reginald I. Vachon ◽  
Gregory L. Hovis ◽  
Jerrell A. Nardiello ◽  
Robert D. Fidnarick ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Crack Initiation ◽  
Crack Growth ◽  
Strain Measurement ◽  
Crack Detection ◽  
Measurement Technology ◽  
Growth Monitoring ◽  
Strain Gages ◽  
Strain Measurements ◽  
Shear Strains

Results are presented for crack initiation detection and crack growth monitoring using DMI SR-1 Strain Gages and DMI SR-2 Reader in two Northrop Grumman aluminum test coupons subjected to cyclic loading. Results demonstrate the utility of the technology to detect cracks and crack growth in holes. The DMI SR-1 strain gage is applied so that it frames the hole in the test coupon. This results in strain measurements at tangents to hole and associated shear strains. A differential strain reading between gage lengths on parallel and opposing sides of a hole, resulting from discontinuities in the material surrounding a hole, indicates crack initiation and as the crack grows the differential reading increases.

Progressive Debonding of Multilayer Interconnect Structures

1997 ◽  
Vol 473 ◽  
Author(s):  
Michael Lane ◽  
Robert Ware ◽  
Steven Voss ◽  
Qing Ma ◽  
Harry Fujimoto ◽  
...  
Keyword(s):  
Thin Films ◽  
Crack Growth ◽  
Driving Force ◽  
Adhesion Energy ◽  
Time Dependent ◽  
Multilayer Thin Films ◽  
Processing Conditions ◽  
Interface Morphology ◽  
Entire Sample ◽  
Crack Growth Velocity

ABSTRACTProgressive (or time dependent) debonding of interfaces poses serious problems in interconnect structures involving multilayer thin films stacks. The existence of such subcriticai debonding associated with environmentally assisted crack-growth processes is examined for a TiN/SiO2 interface commonly encountered in interconnect structures. The rate of debond extension is found to be sensitive to the mechanical driving force as well as the interface morphology, chemistry, and yielding of adjacent ductile layers. In order to investigate the effect of interconnect structure, particularly the effect of an adjacent ductile Al-Cu layer, on subcriticai debonding along the TiN/SiO2 interface, a set of samples was prepared with Al-Cu layer thicknesses varying from 0.2–4.0 μm. All other processing conditions remained the same over the entire sample run. Results showed that for a given crack growth velocity, the debond driving force scaled with Al-Cu layer thickness. Normalizing the data by the critical adhesion energy allowed a universal subcriticai debond rate curve to be derived.

scholarly journals Digital Image Correlation for Evaluation of Cracks in Reinforced Concrete Bridge Slabs

2021 ◽  
Vol 6 (7) ◽  
pp. 99
Author(s):  
Christian Overgaard Christensen ◽  
Jacob Wittrup Schmidt ◽  
Philip Skov Halding ◽  
Medha Kapoor ◽  
Per Goltermann
Keyword(s):  
Reinforced Concrete ◽  
Digital Image Correlation ◽  
Crack Initiation ◽  
Laboratory Test ◽  
Digital Image ◽  
Crack Detection ◽  
Image Correlation ◽  
In Situ Tests ◽  
Stop Criterion

In proof-loading of concrete slab bridges, advanced monitoring methods are required for identification of stop criteria. In this study, Two-Dimensional Digital Image Correlation (2D DIC) is investigated as one of the governing measurement methods for crack detection and evaluation. The investigations are deemed to provide valuable information about DIC capabilities under different environmental conditions and to evaluate the capabilities in relation to stop criterion verifications. Three Overturned T-beam (OT) Reinforced Concrete (RC) slabs are used for the assessment. Of these, two are in situ strips (0.55 × 3.6 × 9.0 m) cut from a full-scale OT-slab bridge with a span of 9 m and one is a downscaled slab tested under laboratory conditions (0.37 × 1.7 × 8.4 m). The 2D DIC results includes full-field plots, investigation of the time of crack detection and monitoring of crack widths. Grey-level transformation was used for the in situ tests to ensure sufficient readability and results comparable to the laboratory test. Crack initiation for the laboratory test (with speckle pattern) and in situ tests (plain concrete surface) were detected at intervals of approximately 0.1 mm to 0.3 mm and 0.2 mm to 0.3 mm, respectively. Consequently, the paper evaluates a more qualitative approach to DIC test results, where crack indications and crack detection can be used as a stop criterion. It was furthermore identified that crack initiation was reached at high load levels, implying the importance of a target load.

Sign in / Sign up

Export Citation Format

Share Document