Multiaxial effects on LCF behaviour and fatigue failure of AZ31B magnesium extrusion

Albinmousa, Jafar; Jahed, Hamid

doi:10.1016/j.ijfatigue.2014.01.025

Cited by 58 publications

(57 citation statements)

References 84 publications

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“…In contrast with the SWT results, the life predictions of the JV model in ED are not scattered, though the maximum stress is included in this model too. The accuracy of the JV energy model has been also reported to be good in multiaxial fatigue life prediction of AZ31B extrusion [4,65].…”

Section: Jahed-varvani (Jv)mentioning

confidence: 86%

“…In order to quantify the damage occurred in the microstructure of a material during cyclic loading, a number of fatigue damage parameters have been proposed and formulated in such a way that incorporates experimental fatigue life [65][66][67]. Available fatigue damage parameters can be categorized into stress-, strain-and energy-based.…”

Section: Fatigue Life Modellingmentioning

confidence: 99%

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Role of loading direction on cyclic behaviour characteristics of AM30 extrusion and its fatigue damage modelling

Roostaei

Jahed

2016

Materials Science and Engineering: A

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a b s t r a c tAnisotropic fatigue and cyclic behaviour of AM30 Mg alloy extrusion is investigated by performing fullyreversed strain-controlled tension-compression cyclic tests at strain amplitudes between 0.3% and 2.3%, along extrusion (ED) and transverse (TD) directions. The shapes of half-life hysteresis loops suggest the predominance of slip and twinning/de-twinning mechanisms below and above the strain amplitude of 0.5%, respectively. The twinning/de-twinning occurrence is found to be more extensive during straining along ED, which results in higher asymmetry of hysteresis loops, and thereby, higher induced mean stress. This adversely affects the fatigue resistance and yields to less number of cycles before failure in ED. Optical microscopy and texture analysis are employed to validate the findings. In addition, fracture surfaces are studied by scanning electron microscopy to identify the sources of fatigue crack initiation. Persistent slip bands (PSBs) and twin lamellae interfaces are evidenced as crack initiation sites at low and high strain amplitudes, respectively. Cracks emanated from debonded inclusion interface are also observed. Lastly, estimated fatigue life by Smith-Watson-Topper (SWT) and Jahed-Varvani (JV) fatigue models are compared with experimental life obtained through this study as well as the ones reported in the literature. The JV energy model is proven to yield better life predictions.

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Section: Jahed-varvani (Jv)mentioning

confidence: 86%

Section: Fatigue Life Modellingmentioning

confidence: 99%

Role of loading direction on cyclic behaviour characteristics of AM30 extrusion and its fatigue damage modelling

Roostaei

Jahed

2016

Materials Science and Engineering: A

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“…Magnesium alloys are getting a lot of attention and have been a focus of many recent experimental and constitutive cyclic modelling studies to understand their multiaxial fatigue behaviour and to model their cyclic plasticity . These experimental studies include extruded and rolled AZ31B, extruded AZ61A, and extruded ZK60 magnesium alloys.…”

Section: Introductionmentioning

confidence: 99%

“…An energy‐based model, the Jahed‐Varvani model, is examined. The Jahed‐Varvani model is originally not a critical plane‐based model; however, Albinmousa et al showed that the model has a potential to be evaluated at the plane of maximum axial strain energy density.…”

Section: Introductionmentioning

confidence: 99%

A method for assessing critical plane‐based multiaxial fatigue damage models

Iftikhar

Albinmousa

2017

Fatigue Fract Eng Mat Struct

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Fatigue failure is a complex phenomenon. Therefore, development of a fatigue damage model that considers all associated complexities resulting from the application of different cyclic loading types, geometries, materials, and environmental conditions is a challenging task. Nevertheless, fatigue damage models such as critical plane-based models are popular because of their capability to estimate life mostly within ±2 and ±3 factors of life for smooth specimens. In this study, a method is proposed for assessing the fatigue life estimation capability of different critical plane-based models. In this method, a subroutine was developed and used to search for best estimated life regardless of critical plane assumption. Therefore, different fatigue damage models were evaluated at all possible planes to search for the best life. Smith-Watson-Topper (normal strain-based), Fatemi-Socie (shear strain-based), and Jahed-Varvani (total strain energy density-based) models are compared by using the proposed assessment method. The assessment is done on smooth specimen level by using the experimental multiaxial fatigue data of 3 alloys, namely, AZ31B and AZ61A extruded magnesium alloys and S460N structural steel alloy. Using the proposed assessment method, it was found that the examined models may not be able to reproduce the experimental lives even if they were evaluated at all physical planes. KEYWORDS critical plane approach, damage assessment method, fatigue damage model, fatigue life estimation, multiaxial fatigue Nomenclature: b, axial fatigue strength exponent; b s , torsional fatigue strength exponent; c, axial fatigue ductility exponent; c s , torsional fatigue ductility exponent; k, Fatemi-Socie constant; B, axial energy-based fatigue strength exponent; B s , torsional energy-based fatigue strength exponent; C, axial energy-based fatigue toughness exponent; C s , torsional energy-based fatigue toughness exponent; E, tensile modulus of elasticity; E ′ e , axial energy-based fatigue strength coefficient; E ′ f , axial energy-based fatigue toughness coefficient; G, shear modulus; N A , fatigue life under purely axial loading; N f , number of cycles to failure; N T , fatigue life under purely torsion loading; W ′ e , torsional energy-based fatigue strength coefficient; W ′ f , torsional energy-based fatigue toughness coefficient; ΔE, total strain energy density; ΔE A , axial strain energy density; ΔE T , torsional strain energy density; Δε 1 , principal normal strain range; Δγ max , maximum shear strain range; ε ′ f , axial fatigue ductility coefficient; γ ′ f , torsional fatigue ductility coefficient; v, Poisson ratio; σ ′ f , axial fatigue strength coefficient; σ n , max , maximum normal stress at critical plane; σ uc , ultimate compressive strength; σ ut , ultimate tensile strength; σ yc , compressive yield strength; σ yt , tensile yield strength; τ ′ f , torsional fatigue strength coefficient

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“…Socie et al [10] emphasized on the consideration of complex geometries and loading conditions for evaluating fatigue models. On the other hand, it is often found that models that are based on completely different critical plane assumptions such as normal or shear still give very similar fatigue life predictions [9,12,13]. Such observation raises two important questions.…”

Section: Introductionmentioning

confidence: 99%

Investigation on parametric representation of proportional and nonproportional multiaxial fatigue responses

Albinmousa

2016

Frattura Ed Integrità Strutturale

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ABSTRACT. This study aims to investigate fatigue damage resulting from multiaxial fatigue, proportional and/or nonproportional, loading by analyzing stresses and strains over a full domain around a representative stress-strain element. Plain stress-strain transformation of multiaxial hysteresis was performed by varying orientation of plane for 0≤φ≤2π. Parametric representations for both normal and shear stresses and strains were obtained by plotting them in polar figures. These figures show that depending on the applied loading stresses and strains represent definitive known parametric curves. Parametric representation of fatigue damage parameter such as Fatemi-Socie suggests that fatigue damage shall be calculated as the sum of the damage values on all planes. The proposed technique has been shown to improve fatigue life prediction compared to that obtained from the critical plane method.

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Multiaxial effects on LCF behaviour and fatigue failure of AZ31B magnesium extrusion

Cited by 58 publications

References 84 publications

Role of loading direction on cyclic behaviour characteristics of AM30 extrusion and its fatigue damage modelling

Role of loading direction on cyclic behaviour characteristics of AM30 extrusion and its fatigue damage modelling

A method for assessing critical plane‐based multiaxial fatigue damage models

Investigation on parametric representation of proportional and nonproportional multiaxial fatigue responses

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