Identification of Crack Initiation in Aluminum Alloys using Acoustic Emission

Vanniamparambil, Prashanth A.; Guclu, U.; Kontsos, Antonios

doi:10.1007/s11340-015-9984-5

Cited by 55 publications

(63 citation statements)

References 31 publications

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“…A popular method for doing so has been to correlate the number times the AE voltage signal crosses a certain amplitude threshold, referred to as counts, and the crack growth rate using a power law relationship [4][5][6][7][8][9][10][11][12][13]. In addition, other AE features have been studied as fatigue cracks grow, such as amplitude [11,12,14,15], energy [14,15], rise time [11,[15][16][17], and average frequency [15][16][17]. While methods for estimating stable crack growth rate based on AE signals are well established, estimating crack damage at the smallest possible scale is most desirable.…”

Section: Introductionmentioning

confidence: 99%

“…While methods for estimating stable crack growth rate based on AE signals are well established, estimating crack damage at the smallest possible scale is most desirable. This idea has motivated researchers to better understand wave dynamics of AE signals within single crystals [18][19][20][21] and polycrystalline materials [11,12,15,[22][23][24][25][26][27][28][29][30] (see [31] for further discussion on past AE literature). From these studies, researchers concluded that AE activity is present during initial damage due to dislocation motion and microcracks, and various AE features can be correlated to damage.…”

Section: Introductionmentioning

confidence: 99%

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Damage Assessment Using Information Entropy of Individual Acoustic Emission Waveforms during Cyclic Fatigue Loading

et al. 2017

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Featured Application: The work presented in this paper outlines three methods to analyze individual acoustic emission waves emitted within a cyclically-loaded metallic structure. Upon further development, one potential application of the proposed analysis methods would be to aid in estimating the remaining useful life of aircraft structures.Abstract: Information entropy measured from acoustic emission (AE) waveforms is shown to be an indicator of fatigue damage in a high-strength aluminum alloy. Three methods of measuring the AE information entropy, regarded as a direct measure of microstructural disorder, are proposed and compared with traditional damage-related AE features. Several tension-tension fatigue experiments were performed with dogbone samples of aluminum 7075-T6, a commonly used material in aerospace structures. Unlike previous studies in which fatigue damage is measured based on visible crack growth, this work investigated fatigue damage both prior to and after crack initiation through the use of instantaneous elastic modulus degradation. Results show that one of the three entropy measurement methods appears to better assess the damage than the traditional AE features, whereas the other two entropies have unique trends that can differentiate between small and large cracks.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Damage Assessment Using Information Entropy of Individual Acoustic Emission Waveforms during Cyclic Fatigue Loading

et al. 2017

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“…Acoustic emission (AE) is defined (ASTM E1316-10c) by the sudden redistribution of energy in a solid caused by the activation and/or development of one or more localized sources, which are typically part of irreversible processes related to deformation and damage across materials including fracture, slip activity, twinning, phase transformations, and delaminations (Chung and KannateyAsibo, 1992;Koslowski et al, 2004;Lamark et al, 2004;Lockner et al, 1991;Lou et al, 2007;Mathis et al, 2006;Miguel et al, 2001;Richeton et al, 2006;van Bohemen et al, 2003;Vanniamparambil et al, 2015;Wisner et al, 2015). More specifically, AE is generated when the energy stored in a material or structure is released and dissipated in the form of transient elastic waves that typically have frequencies in the ultrasonic regime depending on the source size and duration of the damage process, as recently demonstrated by the authors (Cuadra et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Energy dissipation via acoustic emission in ductile crack initiation

et al. 2016

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This article presents a modeling approach to estimate the energy release due to ductile crack initiation in conjunction to the energy dissipation associated with the formation and propagation of transient stress waves typically referred to as Acoustic Emission. To achieve this goal, a ductile fracture problem is investigated computationally using the Finite Elements Method based on a compact tension geometry under Mode I loading conditions. To quantify the energy dissipation associated with Acoustic Emission, a crack increment is produced given a pre-determined notch size in a 3D cohesive-based extended finite element model. The computational modeling methodology consists of defining a damage initiation state from static simulations and linking such state to a dynamic formulation used to evaluate wave propagation and related energy redistribution effects.The model relies on a custom traction separation law constructed using full field deformation measurements obtained experimentally using the Digital Image Correlation method. The amount of energy release due to the investigated first crack increment is evaluated through three different approaches both for verification purposes and to produce an estimate of the portion of the energy that radiates away from the crack source in the form of transient waves. The results presented herein propose an upper bound for the energy dissipation associated to Acoustic Emission, which could assist the interpretation and implementation of relevant nondestructive evaluation methods and the further enrichment of the understanding of effects associated with fracture.

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“…Several nondestructive testing (NDT) techniques including ultrasonic testing (UT) [25,26], acoustic emission (AE) [14,25,[27][28][29][30][31][32][33][34][35][36][37][38][39], digital image correlation (DIC) [14,29,38,[40][41][42], and infrared thermography (IRT) [25,28,38], have been used to gain information on the state of materials subjected to monotonic or cyclic loading. Each technique provides its own advantages and disadvantages in the information it can obtain, while in general all techniques could be used to inform models for prediction of fracture at the component and structural levels [25,29,31,33,39].…”

Section: Introductionmentioning

confidence: 99%

In Situ Microscopic Investigation to Validate Acoustic Emission Monitoring

et al. 2015

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A novel experimental mechanics technique using Scanning Electron Microscopy (SEM) in conjunction with Acoustic Emission (AE) monitoring is discussed to investigate microstructure-sensitive mechanical behavior and damage of metals and to validate AE related information. Validation for the use of AE method was obtained by using aluminum alloy sharp notch specimens with different geometries tested inside the microscope and compared to results obtained outside the microscope, as well as to previously published data on similar investigations at the laboratory specimen scale. Additionally, load data were correlated with both AE information and microscopic observations of microcracks around grain boundaries as well as secondary cracks, voids, and slip bands. The reported AE results are in excellent agreement with similar findings at the mesoscale, while they are further correlated with in situ and post mortem observations of microstructural damage processes.

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Identification of Crack Initiation in Aluminum Alloys using Acoustic Emission

Cited by 55 publications

References 31 publications

Damage Assessment Using Information Entropy of Individual Acoustic Emission Waveforms during Cyclic Fatigue Loading

Damage Assessment Using Information Entropy of Individual Acoustic Emission Waveforms during Cyclic Fatigue Loading

Energy dissipation via acoustic emission in ductile crack initiation

In Situ Microscopic Investigation to Validate Acoustic Emission Monitoring

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