A phenomenological stress–strain model for wrought magnesium alloys under elastoplastic strain-controlled variable amplitude loading

Dallmeier, Johannes; Denk, Josef; Huber, Otto; Saage, Holger; Eigenfeld, K.

doi:10.1016/j.ijfatigue.2015.06.007

Cited by 16 publications

(28 citation statements)

References 53 publications

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“…Based on the literature, the strain‐ and stress‐control cyclic hysteresis loops in this loading condition are asymmetric; the downward halves are convex and the upward halves are concave with inflection points. This trend was also seen in the results obtained in the current research (Fig. ) and can be explained by different deformation mechanisms.…”

Section: Resultsmentioning

confidence: 99%

“…The twinning deformation mechanism is activated in the unloading reversals (downward side) of the hysteresis loop, whereas in the reloading reversals (upward side) there are two different deformation mechanisms at work, detwinning and dislocation slip, which lead to inflection points on the upward side of the hysteresis loop. 24,7 …”

Section: Resultsmentioning

confidence: 99%

“…Dallmeier et al . showed that inflection points of the strain‐control hysteresis loops in AZ31B indicate deformation mechanism changes in the material. Figure ‐a illustrates a typical strain‐control hysteresis curve for AZ31B magnesium alloy.…”

Section: Stress–strain Hysteresesmentioning

confidence: 95%

“…To correlate the FBG strain measurements with the corresponding VMP simulated stresses within one cycle, a mapping function was required. Dallmeier et al 24 showed that inflection points of the strain-control hysteresis loops in AZ31B indicate deformation mechanism changes in the material. Figure 8-a illustrates a typical strain-control hysteresis curve for AZ31B magnesium alloy.…”

Section: S T R E S S -S T R a I N H Y S T E R E S E S A) Elastic-plasmentioning

confidence: 99%

See 3 more Smart Citations

Cyclic hysteresis of AZ31B extrusion under load‐control tests using embedded sensor technology

Marzbanrad

Toyserkani

Jahed

2016

Fatigue Fract Eng Mat Struct

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The fatigue behaviour of AZ31B extrusion magnesium alloy under load‐control cyclic test conditions is estimated using a combination of simulation and experimental results. The strain measurement of this asymmetric material is found experimentally using a Fibre Bragg Grating (FBG) sensor during rotating bending tests. Then, to analyse applied stresses in the sample – particularly in the plastic deformation range – the Variable Material Property (VMP) method is employed. Using this simulation method, the hysteresis loops of two critical top and bottom elements of the sample's cross section under different bending moments are obtained. Finally, the strain of the sample during rotating bending, as measured by the embedded FBG sensor, is related to the stresses obtained from the modeling using a mapping function. The hystereses obtained from this combination of the modeling and experimental results are compared with the results of a companion strain‐control pull–push test in which the input strain history was that of measured by the FBG sensor. Observations verify that the stresses of the combined VMP‐FBG hysteresis loops have good compatibility with the stress responses obtained through the experiment. The hybrid model introduced in this work can be employed to capture cyclic hysteresis, and hence estimate the fatigue life, under load‐controlled rotating bending tests.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Stress–strain Hysteresesmentioning

confidence: 95%

Section: S T R E S S -S T R a I N H Y S T E R E S E S A) Elastic-plasmentioning

confidence: 99%

See 2 more Smart Citations

Cyclic hysteresis of AZ31B extrusion under load‐control tests using embedded sensor technology

Marzbanrad

Toyserkani

Jahed

2016

Fatigue Fract Eng Mat Struct

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“…A largely used approach is the effective notch stress defined by Radaj et al, [2][3][4] where a fictitious notch tip radius is introduced at the weld toe and weld root; the fatigue strength is related to the local notch peak stress. [6][7][8][9][10] The first approach is able to compute the number of cycles up to final failure of an existing crack or defect; the second mainly focuses on crack initiation modelling. 5 Other widely used approaches are based on fracture mechanics or on elastoplastic strain analysis of actual weld geometries; several contributions are present in the literature, even recent papers are available.…”

Section: Introductionmentioning

confidence: 99%

Overview of the geometrical influence on the fatigue strength of steel butt welds by a nonlocal approach

Livieri

Tovo

2019

Fatigue Fract Eng Mat Struct

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The paper deals with the high-cycle fatigue behaviour of steel butt-welded joints in the as-welded condition, under constant amplitude loading. It tackles the problem of strength assessment by changing the geometrical shape and features of the weldment. This investigation considers the recommendations available in design standards, particularly referring to the Eurocodes, and it reanalyses experimental data where a clear profile of the actual weld shape is available. For the available weld profiles, numerical investigations are shown by applying the Implicit Gradient approach for the evaluation of the nonlocal effective stress in the fatigue strength assessment. The results are very promising since the nonlocal approach significantly agrees with design standard recommendations in conventional cases, but it is also able to provide specific indications on the influence of the geometrical features, as well as the tip radius and opening angles, specifying their influence when no explicitly detailed indications are available in the design standards.

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Fatigue modeling for wrought magnesium structures with various fatigue parameters and the concept of highly strained volume

Nischler

Denk

Huber

2020

Continuum Mech. Thermodyn.

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Mechanical fatigue tests of unnotched, notched, and bending twin-roll cast AZ31B magnesium alloy specimens are performed in which strain fields are analyzed with digital image correlation. Clearly, delimited macroscopic bands of twinned grains (BTGs) in which the compressive strain is significantly higher compared to the adjacent regions are observed. Conventional fatigue parameters, e.g., the strain amplitude, exhibited higher values within the BTGs. This findings are confirmed by the fact that for all investigated specimens the initial macroscopic cracks are observed within the BTGs. Consequently, for the presented concept of highly strained volume, fatigue parameters are determined from the highly strained regions with high strain amplitudes. This paper focuses on the application of the effective strain amplitude fatigue parameter decomposed in an elastic and plastic portion, the Smith-Watson-Topper fatigue parameter and energy-based fatigue parameters within the concept of highly strained volume. An extended stress-strain hysteresis model is presented to compute stress-strain hystereses for arbitrary load ratios, required to determine the mentioned fatigue parameters. The application and evaluation of five different fatigue parameters within the concept of highly strained volume demonstrates the accurate description of the fatigue life until failure.

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A phenomenological stress–strain model for wrought magnesium alloys under elastoplastic strain-controlled variable amplitude loading

Cited by 16 publications

References 53 publications

Cyclic hysteresis of AZ31B extrusion under load‐control tests using embedded sensor technology

Cyclic hysteresis of AZ31B extrusion under load‐control tests using embedded sensor technology

Overview of the geometrical influence on the fatigue strength of steel butt welds by a nonlocal approach

Fatigue modeling for wrought magnesium structures with various fatigue parameters and the concept of highly strained volume

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