Numerical Determination of Critical Configuration for Mechanical Properties of Metallic Glasses with Notches

A numerical study based on a revised free-volume theory was carried out to determine the critical configuration for mechanical properties in metallic glass with notches. Firstly, parameters being used in constitutive laws were developed and validated to quantitatively describe the asymmetry of tension and compression. Then, systematical simulations under compressive loadings were performed on samples where different horizontal width and vertical distance of two adjacent notches were designed. Engineering stress-strain curves, global strength and uniform elongation were plotted against individual geometrical configuration. Analyses were carried out to reveal the shear banding process of different samples by means of free-volume distribution obtained by simulations. Conclusive illustration recommended a geometrical configuration by which notched samples could display a remarkable plasticity and high strength. It is helpful to material fabrication for metallic glass based porous materials.

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Numerical Study on the Fatigue Limit of Metallic Glasses under Cyclic Tension-Compression Loading

Materials ◽

10.3390/ma13071732 ◽

2020 ◽

Vol 13 (7) ◽

pp. 1732

Author(s):

Jinfeng Yan ◽

Wenjun Meng ◽

Zhi Chen ◽

Hong Guo ◽

Xianguo Yan

Keyword(s):

Fatigue Life ◽

Metallic Glass ◽

Fatigue Limit ◽

Free Volume ◽

Strain Amplitude ◽

Numerical Study ◽

Hydrostatic Stress ◽

Shear Banding ◽

Engineering Application ◽

Free Volume Theory

Numerical study was performed to determine the fatigue limit of metallic glass under tension-compression cyclic loading. A revised free-volume theory which considers the hydrostatic stress was utilized to make the predictions. Systematical simulations showed that a higher strain amplitude is prone to making the sample completely damaged earlier. However, lower strain fluctuations could result in a longer fatigue life. Shear banding evolution history described by free-volume localization could reasonably explain the mechanical responses of different samples. In addition, compressive loading could give rise to a higher stress than that under tensile loading because of hydrostatic stress contribution. In the end, a correlation between fatigue life and applied strain amplitude was plotted which could supply a guidance for designing the engineering application of metallic glass under periodic loading.

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Notch Effect on Plastic Deformation of Metallic Glass: A Numerical Study by Revised Free-Volume Theory

Advances in Materials Science and Engineering ◽

10.1155/2020/7872815 ◽

2020 ◽

Vol 2020 ◽

pp. 1-13

Author(s):

J. F. Yan ◽

W. J. Meng ◽

Z. Chen ◽

H. Guo ◽

X. G. Yan

Keyword(s):

Metallic Glass ◽

Free Volume ◽

Numerical Study ◽

Shear Bands ◽

Notch Effect ◽

Volume Distribution ◽

Free Volume Theory ◽

Tension And Compression ◽

Strength Asymmetry ◽

Strength And Plasticity

By means of a revised free-volume theory, the notch effect on metallic glass was systematically investigated by the numerical method. Simulations on specimens without notches demonstrated that the parameters being determined in this work could reasonably describe the strength asymmetry of tension and compression. Moreover, four samples with different notches were used to numerically investigate the notch effect on global strength and plasticity. A better agreement could also be achieved between current simulations with existing experimental results, compared with another free-volume model. Combined with the free-volume distribution during deformation process, it was proven that the intersection of two major shear bands is the cause for the strength and plasticity enhancement found in sample with two symmetric notches. Besides, strength asymmetry between tension and compression was also found for notched samples. Compressive strengths are accordingly higher than tensile ones. Moreover, with the augment of the aspect ratio, the plasticity for specimens with two symmetric notches was found to increase firstly and then decrease afterwards.

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Numerical study on deformation behavior of bulk metallic glass composites via modified free-volume theory

Intermetallics ◽

10.1016/j.intermet.2020.106717 ◽

2020 ◽

Vol 119 ◽

pp. 106717

Author(s):

J.X. Zhao ◽

Y.F. Chen ◽

F.F. Wu ◽

J.M. Gong

Keyword(s):

Metallic Glass ◽

Bulk Metallic Glass ◽

Free Volume ◽

Deformation Behavior ◽

Numerical Study ◽

Free Volume Theory ◽

Glass Composites ◽

Bulk Metallic Glass Composites

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Thermo-Mechanical Investigation of Free Volume Theory for Polyamie-6

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.819.580 ◽

2016 ◽

Vol 819 ◽

pp. 580-584

Author(s):

Jamal Umer ◽

Ivan Saprounov ◽

Igor Emri ◽

Barbara Zupančič ◽

Muhammad Wakil Shahzad

Keyword(s):

Mechanical Properties ◽

Free Volume ◽

Polyamide 6 ◽

Time Dependent ◽

Effect Of Temperature ◽

Free Volume Theory ◽

Wlf Equation ◽

Mechanical Investigation ◽

Temperature And Pressure

Polymers always show time-dependent mechanical properties. In order to use polymers in engineering applications, long-term mechanical propertes should be characterized. Free volume theroy is the mostly used theory to predict and model the mechanical properties of polymers. The effect of temperature is modelled thorugh William-Landel-Ferry (WLF) equation, whereas, the combined effect of temperature and pressure is modelled by Filler-Moonan-Tschoegl (FMT) equation. Both of the models are based on free volume theory. A set of expermentations were performed to investigate the validity of free volume concpet for one of the most important engineering polymer; i.e. Polyamide-6.

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Plastic flow in dynamic compression of a Zr-based bulk metallic glass

Journal of Materials Research ◽

10.1557/jmr.2006.0194 ◽

2006 ◽

Vol 21 (6) ◽

pp. 1570-1575 ◽

Cited By ~ 16

Author(s):

W.H. Jiang ◽

F.X. Liu ◽

D.C. Qiao ◽

H. Choo ◽

P.K. Liaw

Keyword(s):

Metallic Glass ◽

Bulk Metallic Glass ◽

Free Volume ◽

Plastic Flow ◽

Dynamic Compression ◽

Maximum Shear Stress ◽

Shear Banding ◽

Shear Bands ◽

Free Volume Model ◽

Geometrically Constrained

Using geometrically constrained specimens, the plastic flow behaviors of the as-cast and the relaxed Zr52.5Cu17.9Ni14.6Al10.0Ti5.0 bulk metallic glass in the dynamic compression were investigated. Both alloys exhibit a significant plasticity in the dynamic compression. The plastic deformation in both alloys is still inhomogeneous, which is characterized by the serrated plastic flow and the formation of shear bands. Free volumes affect the shear banding and the plastic flow. The reduced free volume results in the deviation of the shear banding direction from the maximum shear stress. The relaxed alloy exhibits the obvious stress overshoot, which is consistent with the theoretical prediction using a free volume model.

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