Acoustic Emission Monitoring of Fatigue Crack Growth in Mooring Chains

Offshore installations are subject to perpetual fatigue loading and are usually very hard to inspect. Close visual inspection from the turret is usually too hazardous for divers and is not possible with remotely operated vehicles (ROVs) because of the limited access. Conventional nondestructive techniques (NDTs) have been used in the past to carry out inspections of mooring chains, floating production storage and offloading systems (FPSOs), and other platforms. Although these have been successful at detecting and assessing fatigue cracks, the hazardous nature of the operations calls for remote techniques that could be applied continuously to identify damage initiation and progress. The aim of the present work is to study the capabilities of acoustic emission (AE) as a monitoring tool to detect fatigue crack initiation and propagation in mooring chains. A 72-day large-scale experiment was designed for this purpose. A detailed analysis of the different AE signal time domain features was not conclusive, possibly due to the high level of noise. However, the frequency content of the AE signals offers a promising indication of fatigue crack growth.

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Intrinsic Fatigue Crack Growth in Al-Cu-Li-Mg-Zr Alloys: The Effect of the Iron Constituent Particles

Metals ◽

10.3390/met11010110 ◽

2021 ◽

Vol 11 (1) ◽

pp. 110

Author(s):

Min Hao ◽

Liang Wang ◽

Jun-Zhou Chen ◽

Ren Wang ◽

Guo-Ai Li

Keyword(s):

Fatigue Crack ◽

Fatigue Crack Growth ◽

Crack Growth ◽

Fatigue Testing ◽

Fatigue Cracks ◽

Fatigue Crack Initiation ◽

Metallographic Examination ◽

Fe Content ◽

High Level ◽

Zr Alloys

The influence of iron (Fe)-containing constituent particles on the behavior of fatigue crack initiation and propagation of Al-Cu-Li-Mg-Zr alloys has been studied using fatigue crack growth (FCG) tests and in-situ fatigue testing and detailed metallographic examination based on scanning electron microscopy. Experimental results show that the alloy with a low level of Fe content (2A97-T3 sheet) exhibited a lower density, accompanying equivalent tensile strength and FCG rate compared to the damage-tolerant 2524-T3 sheet. It was found that the fatigue b growth of both alloys is dominated by transgranular mode, accompanied by intergranular expansion, and the high level of Fe content alloy presents more characteristics of intergranular. Coarse constituent particles were detrimental to the resistance against FCG. It is postulated here that the micro-cracks formed around the coarse Fe-containing particles are merged with the primary crack to produce a bridging effect, accelerating the growth of fatigue cracks in the alloy with a high level of Fe content.

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Guided Wave Acoustic Emission from Fatigue Crack Growth in Aluminium Plate

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.13-14.23 ◽

2006 ◽

Vol 13-14 ◽

pp. 23-28 ◽

Cited By ~ 2

Author(s):

C.K. Lee ◽

Jonathan J. Scholey ◽

Paul D. Wilcox ◽

M.R. Wisnom ◽

Michael I. Friswell ◽

...

Keyword(s):

Acoustic Emission ◽

Fatigue Crack ◽

Fatigue Crack Growth ◽

Crack Growth ◽

Elastic Waves ◽

Fatigue Cracks ◽

Guided Wave ◽

Experimental Results ◽

Multiple Reflections ◽

Alloy Plate

Acoustic emission (AE) testing is an increasingly popular technique used for nondestructive evaluation (NDE). It has been used to detect and locate defects such as fatigue cracks in real structures. The monitoring of fatigue cracks in plate-like structures is critical for aerospace industries. Much research has been conducted to characterize and provide quantitative understanding of the source of emission on small specimens. It is difficult to extend these results to real structures as most of the experiments are restricted by the geometric effects from the specimens. The aim of this work is to provide a characterization of elastic waves emanating from fatigue cracks in plate-like structures. Fatigue crack growth is initiated in large 6082 T6 aluminium alloy plate specimens subjected to fatigue loading in the laboratory. A large specimen is utilized to eliminate multiple reflections from edges. The signals were recorded using both resonant and nonresonant transducers attached to the surface of the alloy specimens. The distances between the damage feature and sensors are located far enough apart in order to obtain good separation of guided-wave modes. Large numbers of AE signals are detected with active fatigue crack propagation during the experiment. Analysis of experimental results from multiple crack growth events are used to characterize the elastic waves. Experimental results are compared with finite element predictions to examine the mechanism of AE generation at the crack tip.

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Estimation of the Shape Evolution and the Growth History of an Embedded Crack by Fatigue Loading

Volume 3: Materials Technology; Jan Vugts Symposium on Design Methodology of Offshore Structures; Jo Pinkster Symposium on Second Order Wave Drift Forces on Floating Structures; Johan Wichers Symposium on Mooring of Floating Structures in Waves ◽

10.1115/omae2011-49457 ◽

2011 ◽

Author(s):

Koji Gotoh ◽

Keisuke Harada ◽

Yosuke Anai

Keyword(s):

Fatigue Crack ◽

Fatigue Crack Growth ◽

Crack Growth ◽

Fatigue Cracks ◽

Estimation Method ◽

Estimation Procedure ◽

Fatigue Loading ◽

Shape Evolution ◽

Crack Growth Behaviour ◽

Embedded Crack

Fatigue life estimation for planar cracks, e.g. part-through surface cracks or embedded cracks is very important because most of fatigue cracks found in welded built-up structures show planar crack morphologies. Fatigue crack growth behaviour of an embedded crack in welded joints is investigated in this study. The estimation procedure of crack shape evolution for an embedded crack is introduced and validation of the estimation procedure of fatigue crack growth based on the numerical simulation of fatigue crack growth with EDS concept for an embedded crack is performed. The validity of the proposed shape evolution estimation method and the fatigue crack growth simulation based on the fracture mechanics approach with EDS concept are confirmed.

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Experimental and Analytical Studies on the Effect of Excessive Loading on Fatigue Crack Propagation in Piping Materials

Volume 6: Materials and Fabrication, Parts A and B ◽

10.1115/pvp2009-77682 ◽

2009 ◽

Cited By ~ 4

Author(s):

Yoshihito Yamaguchi ◽

Jinya Katsuyama ◽

Kunio Onizawa ◽

Hideharu Sugino ◽

Yinsheng Li ◽

...

Keyword(s):

Fatigue Crack ◽

Fatigue Crack Growth ◽

Crack Growth ◽

Large Scale ◽

Fatigue Cracks ◽

Plastic Region ◽

Retardation Effect ◽

Seismic Motion ◽

Loading Patterns ◽

Piping Systems

The seismic regulatory guide was revised in September 2006 and the Niigata-ken Chuetsu-oki earthquake, whose magnitude was beyond the design base seismic motion, occurred in July 2007. Due to these events, attention is being drawn to the evaluation of the effects of large scale earthquakes for some piping systems in which SCC and/or fatigue cracks may potentially occur. Many papers have been already published about the retardation effect that excessive loading has on fatigue crack growth. The retardation effect is treated qualitatively in regard to the plastic strain generated by excessive loading. In this work, crack growth after excessive loading is evaluated for carbon steel and austenitic stainless steel. Some cyclic excessive loading patterns such as stepwise increases or decreases were applied to fatigue crack growth experiments. The FEM analyses were conducted to evaluate the plastic region size during these loading conditions. PFM analyses were performed to evaluate the extent to which the retardation of crack growth influences the probability of failure.

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Acoustic emission sensor effect and waveform evolution during fatigue crack growth in thin metallic plate

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x17730930 ◽

2017 ◽

Vol 29 (7) ◽

pp. 1275-1284 ◽

Cited By ~ 6

Author(s):

Md Yeasin Bhuiyan ◽

Bin Lin ◽

Victor Giurgiutiu

Keyword(s):

Acoustic Emission ◽

Fatigue Crack ◽

Fatigue Crack Growth ◽

Crack Growth ◽

Fatigue Loading ◽

Emission Measurement ◽

Acoustic Emission Sensor ◽

Active Sensor ◽

Piezoelectric Wafer ◽

Sensor Transducer

In this article, the effect of the acoustic emission sensor on the acoustic emission waveforms from fatigue crack growth in a thin aerospace specimen is presented. In situ acoustic emission fatigue experiments were performed on the test coupons made of aircraft grade aluminum plate. Commercial Mistras S9225 acoustic emission sensor and piezoelectric wafer active sensor were used to capture the acoustic emission waveforms from the fatigue crack. It has been shown that the piezoelectric wafer active sensor transducer successfully captured the fatigue crack–related acoustic emission waveforms in the thin plate. The piezoelectric wafer active sensor transducer seems to capture more frequency information of the acoustic emission waveform than the conventional acoustic emission sensor in this particular application. We have also shown the evolution of the acoustic emission waveforms as the fatigue crack grows. The signatures of the fatigue crack growth were captured by the evolution of the acoustic emission waveforms. This waveform evolution is highly related to the physical boundary conditions of the cracks as well as the fatigue crack growth mechanism. The fatigue loading and acoustic emission measurement were synchronized using the same acoustic emission instrumentation. This synchronization provided the exact load level when the acoustic emission signals had occurred during the fatigue crack growth.

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Determining the Characteristics of Acoustic Emission in the Fatigue Crack Growth of Aluminum Alloy 2025 for Online Structural Monitoring

10.5772/intechopen.99360 ◽

2021 ◽

Author(s):

Javad Sharifi Ghaderi

Keyword(s):

Acoustic Emission ◽

Aluminum Alloy ◽

Fatigue Crack ◽

Fatigue Crack Growth ◽

Crack Growth ◽

Fatigue Cracks ◽

Structural Monitoring ◽

Acoustic Emission Method ◽

Emission Method ◽

Non Destructive

In the use of metals, due to industrial advances and the application of more dynamic loads, it is necessary to pay more attention to the fatigue issue. Non-destructive inspection methods are used to condition and health monitoring of structures at the time of production and even during the service life of parts. Among non-destructive methods, the acoustic emission method has become a standard and reliable method in recent years. In this project, the characteristics of acoustic emission in the fatigue crack growth of aluminum alloy 2025 for online structural monitoring have been investigated and determined. Acoustic emission tests have been performed in two parts: bending fatigue test with the aim of initiation of fatigue cracks in aluminum alloy 2025 specimens and following tensile tests with the aim of growth of fatigue cracks. The acoustic emission signals and parameters sent by the acoustic emission sensor during both tests were received and recorded by the acoustic emission software. According to the received acoustic emission information, various diagrams are plotted. Analyzing the results from online acoustic emission monitoring showed, the acoustic emission method can be considered as a suitable and reliable technique for detecting crack initiation and crack growth in aluminum alloy 2025.

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A Probabilistic Approach to Small Fatigue Crack Initiation and Sizing Using Acoustic Emission

10.20944/preprints201702.0062.v1 ◽

2017 ◽

Cited By ~ 1

Author(s):

Azadeh Keshtgar ◽

Mohammad Modarres

Keyword(s):

Acoustic Emission ◽

Fatigue Crack ◽

Crack Initiation ◽

Health Management ◽

Fatigue Cracks ◽

Probabilistic Approach ◽

Fatigue Crack Initiation ◽

Fatigue Loading ◽

Accurate Estimation ◽

Small Fatigue Crack

One of the major concerns in structural health management (SHM) is the early detection of a growing crack. Using this, future damage due to crack propagation can be mitigated or eliminated by implementing proper repair and maintenance. Acoustic Emission (AE) is a non-destructive testing (NDT) method with potential applications for locating and monitoring fatigue cracks. The research presented in this paper focuses on SHM using AE. A novel AE signal analysis approach was proposed in order to detect crack initiation and assess small crack lengths. Experimental investigation indicated that initiation of a crack could be identified through the statistical analysis of the resulting features of the AE signals. A probabilistic AE-based model for small fatigue crack sizing was developed and the uncertainties of the model were estimated. In addition, a probabilistic model validation approach was implemented to confirm accurate estimation of the results. The outcome of this research can be used to evaluate the integrity of structures under fatigue loading. The proposed approach can also be applied as an approach to manage health and assess prognosis of structures.

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Advantageous Description of Short Fatigue Crack Growth Rates in Austenitic Stainless Steels with Distinct Properties

Metals ◽

10.3390/met11030475 ◽

2021 ◽

Vol 11 (3) ◽

pp. 475

Author(s):

Lukáš Trávníček ◽

Ivo Kuběna ◽

Veronika Mazánová ◽

Tomáš Vojtek ◽

Jaroslav Polák ◽

...

Keyword(s):

Fatigue Crack ◽

Fatigue Crack Growth ◽

Crack Growth ◽

Stainless Steels ◽

Growth Rates ◽

Large Scale ◽

J Integral ◽

Scale Yielding ◽

Residual Fatigue ◽

Crack Growth Rates

In this work two approaches to the description of short fatigue crack growth rate under large-scale yielding condition were comprehensively tested: (i) plastic component of the J-integral and (ii) Polák model of crack propagation. The ability to predict residual fatigue life of bodies with short initial cracks was studied for stainless steels Sanicro 25 and 304L. Despite their coarse microstructure and very different cyclic stress–strain response, the employed continuum mechanics models were found to give satisfactory results. Finite element modeling was used to determine the J-integrals and to simulate the evolution of crack front shapes, which corresponded to the real cracks observed on the fracture surfaces of the specimens. Residual fatigue lives estimated by these models were in good agreement with the number of cycles to failure of individual test specimens strained at various total strain amplitudes. Moreover, the crack growth rates of both investigated materials fell onto the same curve that was previously obtained for other steels with different properties. Such a “master curve” was achieved using the plastic part of J-integral and it has the potential of being an advantageous tool to model the fatigue crack propagation under large-scale yielding regime without a need of any additional experimental data.

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