A structural integrity prognosis system

Papazian, John M.; Anagnostou, Elias L.; Engel, Stephen J.; Hoitsma, D.; Madsen, John S.; Silberstein, R. P.; Welsh, Greg; Whiteside, J.

doi:10.1016/j.engfracmech.2008.09.007

Cited by 44 publications

(20 citation statements)

References 10 publications

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“…17 However, the knowledge of the electrochemical properties of intermetallics to better predict the localized corrosion in different environments, and more generally in damage modeling, are yet to be fully exploited. 43 …”

Section: Journal Of the Electrochemical Society 161 (12) C535-c543 (mentioning

confidence: 99%

Electrochemical Characterization of Intermetallic Phases Common to Aluminum Alloys as a Function of Solution Temperature

Cavanaugh

Birbilis

et al. 2014

J. Electrochem. Soc.

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A practically important scenario in the corrosion of aluminum (Al) alloys is the variation in damage characteristics, i.e. mode, rate and morphology, as function of environmental temperature. In order to address this problem from a mechanistic point of view, this paper presents results for corrosion potentials, pitting potentials and electrochemical characteristics for intermetallic particles commonly present in high strength aluminum alloys, for tests conducted in 0.1M NaCl of varying temperature. Tests were conducted between 0 and 60 • C via the use of a micro-capillary electrochemical cell. The intermetallics investigated were Mg 2 Si, MgZn 2 , Al 7 Cu 2 Fe, Al 2 Cu, Al 2 CuMg and Al 3 Fe. Analysis of the results reveals that the electrochemical behavior of such compounds is heavily dependent on temperature, with ramifications for localized corrosion (and protection) In the most general sense, corrosion represents the adverse intersection between a material and the environment; while in the case of aluminum (Al) alloys, their prescription is widespread and covers many environmental exposure conditions. For a given material, the environment is responsible for the type and extent of corrosion that may result; warranting an investigation of the electrochemical characteristics as function of environment. [1][2][3][4][5][6] In an attempt to unambiguously characterize the mechanistic aspects of localized corrosion of heterogeneously structured high-strength Al-alloys, we have presented the electrochemical characteristics for a number of intermetallic particles and phases common to a large range of such alloys, [7][8][9][10] paying particular attention to the effect of chloride concentration 9 and the effect of solution pH.7 This approach has also recently been followed for investigation of the second phases that occur in magnesium alloys. 11It has been shown that both [Cl − ] and pH have a significant effect upon the corrosion morphology and rate of bulk Al-alloys, as demonstrated for AA7075-T651. 12 Of key relevance to the work herein, it was shown that the resultant alloy corrosion was able to be reconciled in terms of both morphology and rate, from knowledge of the individual electrochemical characteristics of the alloy constituents.13 Furthermore, it is of importance to note that the associated electrochemical kinetics upon alloy constituents is not trivial, in that kinetics may not be accurately predicted based upon composition or knowledge of corrosion potentials alone. However, polarization testing was able to reveal significant quantitative insights allowing a leap in understanding the origins of localized corrosion (and in some cases the absence of localized corrosion). Examples include; spontaneous passivity of Mg 2 Si at alkaline pH and the increase in the ability of Fe-containing intermetallics to sustain ORR as either pH or [Cl − ] increase, to name but a couple of important factors. 7,9 Similarly, such richness is not predicted by methods such as SKPFM, which has been previously used to predict loca...

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Section: Journal Of the Electrochemical Society 161 (12) C535-c543 (mentioning

confidence: 99%

Electrochemical Characterization of Intermetallic Phases Common to Aluminum Alloys as a Function of Solution Temperature

Cavanaugh

Birbilis

et al. 2014

J. Electrochem. Soc.

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“…Based on this work, a SHM study by Papazian, et al [24] defined a physically small crack to be between the incubated size (starting about 2.8 µm) and a crack size that is treatable by the linear elastic fracture mechanics (LEFM) models, which is about 250 µm for AL7056-T651.…”

Section: Fatigue Crack Initiation and Small Crackmentioning

confidence: 99%

“…It is determined, however, that this crack initiation length is about a quarter of the average grain diameter for Al7075. It has been shown that approximately a 1-mm 3 of the above-mentioned material contains 700 grains [24]. Assuming spherical geometry of grains, the volume of each grain is about 1.43×10-3 mm 3 and the diameter of each grain can be estimated as 0.140 mm (140 µm).…”

Section: Fatigue Crack Initiation and Small Crackmentioning

confidence: 99%

“…Some consider crack initiation as corresponding with a fatigue phenomenon and some associate it with an arbitrarily specified crack length. For example, the U.S. Navy defines the presence of a crack 250 µm in length, as the point where crack initiation occurs [24], [25]. Furthermore, others consider a crack length ranging from a size of grain diameter to about 100 µm as crack initiation length depending on material and scale of interest.…”

Section: Fatigue Crack Initiation and Small Crackmentioning

confidence: 99%

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

Keshtgar

Modarres

2017

Preprint

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Abstract: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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“…Interdisciplinary advances in deformation processing [144], fatigue [145], stress corrosion cracking (SCC) [146], and hydrogen embrittlement [147] illustrate this cutting-edge approach. Internal hydrogen and hydrogen environment assisted cracking degrade high toughness alloys in fracture-critical aerospace, ship, energy, and ground transportation structures [133].…”

Section: Introductionmentioning

confidence: 99%

Strain Gradient Plasticity-Based Modeling of Damage and Fracture

Martínez‐Pañeda¹

2018

Springer Theses

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A structural integrity prognosis system

Cited by 44 publications

References 10 publications

Electrochemical Characterization of Intermetallic Phases Common to Aluminum Alloys as a Function of Solution Temperature

Electrochemical Characterization of Intermetallic Phases Common to Aluminum Alloys as a Function of Solution Temperature

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

Strain Gradient Plasticity-Based Modeling of Damage and Fracture

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