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Journal ArticleDOI

Multiaxial fatigue: An overview and some approximation models for life estimation

01 Aug 2011-International Journal of Fatigue (Elsevier)-Vol. 33, Iss: 8, pp 948-958
TL;DR: In this article, a brief overview of some important issues in multiaxial fatigue and life estimation is presented, including damage mechanisms and damage quantification parameters, material constitutive response and non-proportional hardening, cycle counting and damage accumulation in variable amplitude loading, and mixed-mode crack growth.
About: This article is published in International Journal of Fatigue.The article was published on 2011-08-01. It has received 298 citations till now.
Citations
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TL;DR: In this paper, the authors provide an overview of the mechanical characteristics and behavior of metallic parts fabricated via direct laser deposition (DLD), while also discussing methods to optimize and control the DLD process.
Abstract: The mechanical behavior, and thus ‘trustworthiness’/durability, of engineering components fabricated via laser-based additive manufacturing (LBAM) is still not well understood. This is adversely affecting the continual adoption of LBAM for part fabrication/repair within the global industry at large. Hence, it is important to determine the mechanical properties of parts fabricated via LBAM as to predict their performance while in service. This article is part of two-part series that provides an overview of Direct Laser Deposition (DLD) for additive manufacturing (AM) of functional parts. The first part (Part I) provides a general overview of the thermo-fluid physics inherent to the DLD process. The objective of this current article (Part II) is to provide an overview of the mechanical characteristics and behavior of metallic parts fabricated via DLD, while also discussing methods to optimize and control the DLD process. Topics to be discussed include part microstructure, tensile properties, fatigue behavior and residual stress – specifically with their relation to DLD and post-DLD process parameters (e.g. heat treatment, machining). Methods for controlling/optimizing the DLD process for targeted part design will be discussed – with an emphasis on monitored part temperature and/or melt pool morphology. Some future challenges for advancing the knowledge in AM-part adoption are discussed. Despite various research efforts into DLD characteristics and process optimization, it is clear that there are still many areas that require further investigation.

737 citations

Journal ArticleDOI
TL;DR: In this article, the authors focus on the current state of knowledge pertaining to the mechanical characteristics of metallic parts fabricated via additive manufacturing (AM), as well as the ongoing challenges and imminent opportunities in fabricating materials with increased fatigue resistance.

580 citations


Cites background from "Multiaxial fatigue: An overview and..."

  • ...Variation of FS damage parameter with plane orientation under in-phase (IP) and 90 out-of-phase (OP) axial–torsion loadings at the same strain levels [80]....

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  • ...The multiaxial stresses in critical elements of components and structures not only arise from multidirectional loading, stress concentrations, or residual stresses [80], but also from the heterogeneity of the microstructure, specifically for AMmaterials....

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  • ...Damage observations suggest critical plane approaches, which reflect the physical mechanism of the fatigue damage process, are most reliable and robust for multiaxial fatigue life estimations [80]....

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Journal ArticleDOI
TL;DR: In this paper, the authors attempted to catalog and analyze the published fatigue performance data of an additively manufactured alloy of significant technological interest, Ti-6Al-4V, focusing on uniaxial fatigue performance, discussing failure mechanisms, defects, microstructure and processing parameters.

387 citations

Journal ArticleDOI
TL;DR: Results indicate that stochastic FE analysis-based scheme provides more conservative predictions than the probabilistic S-N curves-based one.

211 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a review of fatigue life prediction techniques for metallic materials, including linear damage rule (LDR)-based, multiaxial and variable amplitude loading, stochastic-based, energy-based and continuum damage mechanics methods.
Abstract: Metallic materials are extensively used in engineering structures and fatigue failure is one of the most common failure modes of metal structures. Fatigue phenomena occur when a material is subjected to fluctuating stresses and strains, which lead to failure due to damage accumulation. Different methods, including the Palmgren-Miner linear damage rule- (LDR-) based, multiaxial and variable amplitude loading, stochastic-based, energy-based, and continuum damage mechanics methods, forecast fatigue life. This paper reviews fatigue life prediction techniques for metallic materials. An ideal fatigue life prediction model should include the main features of those already established methods, and its implementation in simulation systems could help engineers and scientists in different applications. In conclusion, LDR-based, multiaxial and variable amplitude loading, stochastic-based, continuum damage mechanics, and energy-based methods are easy, realistic, microstructure dependent, well timed, and damage connected, respectively, for the ideal prediction model.

185 citations


Cites methods from "Multiaxial fatigue: An overview and..."

  • ...For the multiaxial fatigue life prediction, critical plane approaches linked to the fatigue damage of the material can be found in literature; these approaches are based either on the maximum shear failure plane or on the maximum principal stress (or strain) failure plane [190]....

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References
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Journal ArticleDOI

4,211 citations


"Multiaxial fatigue: An overview and..." refers background in this paper

  • ...According to the MTS criterion, the crack extends in a direction corresponding to the maximum tangential stress....

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  • ...Observed crack growth directions and paths in plate specimens subjected to mixed-mode I and II loading have been found to be close to those based on the MTS criterion in [46]....

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  • ...Maximum tangential stress (MTS) [47] and minimum strain energy density [48] criteria have been widely used because of their simplicity and support by experimental observations....

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Journal ArticleDOI
G.C. Sih1
TL;DR: In this paper, the authors investigated the general problem of crack extension in a combined stress field where a crack can grow in any arbitrary direction with reference to its original position, and showed that the direction of crack growth and fracture toughness for the mixed problem of Mode I and Mode II are governed by the critical value of the strain-energy-density factor.
Abstract: This paper deals with the general problem of crack extension in a combined stress field where a crack can grow in any arbitrary direction with reference to its original position. In a situation, when both of the stress-intensity factors,k 1,k 2 are present along the crack front, the crack may spread in any direction in a plane normal to the crack edge depending on the loading conditions. Preliminary results indicate that the direction of crack growth and fracture toughness for the mixed problem of Mode I and Mode II are governed by the critical value of the strain-energy-density factor,S cr. The basic assumption is that crack initiation occurs when the interior minimum ofS reaches a critical value designatedS cr. The strain-energy-density factorS represents the strength of the elastic energy field in the vicinity of the crack tip which is singular of the order of 1/r where the radial distancer is measured from the crack front. In the special case of Mode I crack extensionS cr is related tok 1c alone asS cr = (κ − 1)k 1 2 /8μ. In general,S takes the quadratic forma 1 1 k 1 + 2a 1 2 k 1 k 2 +a 2 2 k 2 whose critical value is assumed to be a material constant. The analytical predictions are in good agreement with experimental data on the problem of an inclined crack in plexiglass and aluminum alloy specimens. The result of this investigation provides a convenient procedure for determining the critical crack size that a structure will tolerate under mixed mode conditions for a given applied stress.

2,066 citations


"Multiaxial fatigue: An overview and..." refers background in this paper

  • ...Maximum tangential stress (MTS) [47] and minimum strain energy density [48] criteria have been widely used because of their simplicity and support by experimental observations....

    [...]

Journal ArticleDOI
TL;DR: A mathematical representation of the multiaxial Bauschinger effect of materials at high temperatures was presented in this paper. But the model was not considered in this paper, nor in the paper.
Abstract: (2007) A mathematical representation of the multiaxial Bauschinger effect Materials at High Temperatures: Vol 24, No 1, pp 1-26

1,583 citations


"Multiaxial fatigue: An overview and..." refers methods in this paper

  • ...The Armstrong–Frederick incremental plasticity model [21] has been shown in several studies, such as [22,23], as a proper basis for modeling various features of material behavior, including non-proportional hardening....

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Journal ArticleDOI
TL;DR: In this paper, a modification to Brown and Miller's critical plane approach is proposed to predict multiaxial fatigue life under both in-phase and out-of-phase loading conditions.
Abstract: — A modification to Brown and Miller's critical plane approach is proposed to predict multiaxial fatigue life under both in-phase and out-of-phase loading conditions. The components of this modified parameter consist of the maximum shear strain amplitude and the maximum normal stress on the maximum shear strain amplitude plane. Additional cyclic hardening developed during out-of-phase loading is included in the normal stress term. Also, the mathematical formulation of this new parameter is such that variable amplitude loading can be accommodated. Experimental results from tubular specimens made of 1045 HR steel under in-phase and 90° out-of-phase axial-torsional straining using both sinusoidal and trapezoidal wave forms were correlated within a factor of about two employing this approach. Available Inconel 718 axial-torsional data including mean strain histories were also satisfactorily correlated using the aforementioned parameter.

1,493 citations


"Multiaxial fatigue: An overview and..." refers background in this paper

  • ...Fatemi–Socie (FS) parameter [32] for shear failure mode materials (i....

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Journal ArticleDOI
TL;DR: In this paper, the main ingredients and assumptions of developing macroscopic inelastic constitutive equations, mainly for metals and low strain cyclic conditions, have been discussed, with some comparisons with the previous ones, including more recent developments that offer potential new capabilities.

1,414 citations


"Multiaxial fatigue: An overview and..." refers methods in this paper

  • ...The Armstrong–Frederick incremental plasticity model [21] has been shown in several studies, such as [22,23], as a proper basis for modeling various features of material behavior, including non-proportional hardening....

    [...]