Shear band multiplication aided by free volume underthree-point bending

2010 ◽  
Vol 25 (2) ◽  
pp. 283-291 ◽  
Author(s):  
Lincai Zhang ◽  
Feng Jiang ◽  
Yanglei Zhao ◽  
Shibin Pan ◽  
Lin He ◽  
...  
Keyword(s):  
Shear Band ◽  
Free Volume ◽  
Shear Banding ◽  
Stress Gradient ◽  
Shear Bands ◽  
Bending Test ◽  
Three Point Bending ◽  
Deformation Ability ◽  
Plate Geometry

Zr52.5Cu17.9Ni14.6Al10Ti5 bulk metallic glass (BMG) alloy samples in both rod and plate geometry were prepared. Different free volume states were obtained through thermal treatment. The plastic deformation ability of the BMGs was investigated through both a three-point bending test and compression test. The three-point bending results reveal the important role of free volume content on the formation of multiple shear bands, as the shear band propagation can be efficiently stopped due to the existence of the stress gradient from the surface to the neutral plane. In compression, the sample size rather than free volume controls the shear banding behavior.

Shear Band Feature in Two Bulk Metallic Glasses with Different Inherent Plasticity

2013 ◽  
Vol 703 ◽  
pp. 20-23
Author(s):  
Jian Sheng Gu ◽  
Hui Feng Bo ◽  
Hong Li ◽  
Zhan Xin Zhang
Keyword(s):  
Plastic Deformation ◽  
Shear Band ◽  
Temperature Rise ◽  
Metallic Glasses ◽  
Shear Banding ◽  
Shear Bands ◽  
Significant Difference ◽  
Coating Method ◽  
Deformation Ability

Shear banding characterization of Zr64.13Cu15.75Ni10.12Al10 and Zr65Cu15Ni10Al10 BMGs was studied by using Rockwell indention method. The significant difference in plastic deformation ability can be ascribed to different shear banding features. Meanwhile, by using the fusible coating method, thermal effect on shear bands was investigated. We did not see apparently temperature rise in shear bands of these two BMGs through Rockwell indentation.

Characterization of Shear Bands in Zr64.13Cu15.75Ni10.12Al10 and Zr65Cu15Ni10Al10 BMGs

2013 ◽  
Vol 703 ◽  
pp. 24-28
Author(s):  
Jian Sheng Gu ◽  
Hui Feng Bo ◽  
Hong Li ◽  
Zhan Xin Zhang
Keyword(s):  
Plastic Deformation ◽  
Shear Band ◽  
Shear Banding ◽  
Shear Bands ◽  
Band Pattern ◽  
Significant Difference ◽  
Deformation Ability

Shear banding characterization of Zr64.13Cu15.75Ni10.12Al10and Zr65Cu15Ni10Al10BMGs was studied by using Rockwell indention method. Well-developed shear band pattern can be found for both BMGs after indentation. The significant difference in plastic deformation ability can be ascribed to different shear banding features.

The influence of material non-uniformity preceding shear-band formation in a model for granular flow

1997 ◽  
Vol 8 (5) ◽  
pp. 457-483 ◽  
Author(s):  
DAVID G. SCHAEFFER ◽  
MICHAEL SHEARER
Keyword(s):  
Shear Band ◽  
Material Properties ◽  
Shear Banding ◽  
Shear Bands ◽  
Small Variation ◽  
Band Formation ◽  
Time Period ◽  
Single Location ◽  
Change Of Type ◽  
Short Time

The onset of shear-banding in a deforming elastoplastic solid has been linked to change of type of the governing partial differential equations. If uniform material properties are assumed, then (i) deformations prior to shear-banding are uniform, and (ii) the onset of shear-banding occurs simultaneously at all points in the sample. In this paper we study, in the context of a model for anti-plane shearing of a granular material, the effect of a small variation in material properties (e.g. in yield strength) within the sample. Using matched asymptotic expansions, we find that (i) the deformation is extremely non-uniform in a short time period immediately preceding the formation of shear-bands; and (ii) generically, a shear-band forms at a single location in the sample.

Effect of Structure Relaxation on the Plastic Deformation Behaviour in a Zr-Based BMG under Indenter

2009 ◽  
Vol 618-619 ◽  
pp. 437-441
Author(s):  
Hao Wen Xie ◽  
Peter D. Hodgson ◽  
Cui E Wen
Keyword(s):  
Plastic Deformation ◽  
Shear Band ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Free Volume ◽  
Cast Alloy ◽  
Deformation Behaviour ◽  
Shear Bands ◽  
Structure Relaxation ◽  
Effect Of Structure

Vickers and nano indentations were performed on a structurally relaxed Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG), and the evolution of the shear bands in the relaxed BMG was investigated and compared to that in the as-cast alloy. Results indicate that the plastic deformation in the BMG with structure relaxation is accommodated by the semicircular (primary) and radial (secondary) as well as tertiary shear bands. Quantitatively, the shear band density in the relaxed alloy was much lower than that in the as-cast alloy. The annihilation of free volume caused by the annealing was responsible for the embrittlement of the sample with structure relaxation.

Assessment of Fracture Toughness Using Small Punch Tests of Prenotched Specimens

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Yangyan Zheng ◽  
Xiao Chen ◽  
Zheng Yang ◽  
Xiang Ling
Keyword(s):  
Fracture Toughness ◽  
Numerical Simulations ◽  
Stress Gradient ◽  
Element Model ◽  
Bending Test ◽  
J Integral ◽  
Notched Specimen ◽  
Small Punch ◽  
Three Point Bending ◽  
The Difference

In this paper, line- and ring-notched small punch test (SPT) specimens were studied; a three-dimensional (3D) model of a ring-notched SPT specimen was established using the contour integral method, and the validity of the model was verified using ring-notched specimens. The stress and strain fields were analyzed using numerical simulations of a ring-notched SPT specimen, and the change in the stress gradient during deformation was considered. To verify the finite element model, the results of the numerical simulations were compared with those of three-point bending tests and a Gurson–Tvergaard–Needleman (GTN) model. Compared with the line-notched specimen, the ring-notched specimen was more suitable for notch propagation analysis and fracture toughness evaluation. The results of the numerical simulations were in good agreement with those of the experiments, which showed that the numerical model used in this study was correct. For a notch that initiated when the load reached its maximum value, the value of the J integral was 335 × 10−6 kJ/mm2, and at time 0.85Pmax, the value of the J integral was 201 × 10−6 kJ/mm2, and the difference from the result of the three-point bending test was 14.4%. For a notch that initiated during the stretching deformation stage, the relevant fracture toughness was 225 × 10−6 kJ/mm2, and the difference from the result of the three-point bending test was 3%.

Toward Understanding Size-Dependent Plasticity of Nanolayered Metallic Composites

2009 ◽  
Vol 633-634 ◽  
pp. 637-646
Author(s):  
G.P. Zhang ◽  
Y.P. Li ◽  
X.F. Zhu
Keyword(s):  
Fracture Stress ◽  
Shear Banding ◽  
High Hardness ◽  
Plastic Instability ◽  
Indentation Load ◽  
Bending Test ◽  
Tensile Fracture ◽  
Length Scale ◽  
Length Scales ◽  
Three Point Bending

Deformation and fracture behaviors of Cu/Au and Cu/Cr multilayered composites with different length scales were investigated by using instrumented-indentation and three-point-bending methods. It is found that with decreasing the length scale (layer thickness and grain size), both multilayers tend to produce plastic instability via localized shear banding under indentation load in spite of high hardness they have, while quasi-brittle fracture under relatively low fracture stress prevails at three-point-bending test. Especially, the compressive flow stress and the tensile fracture stress exhibit inverse trend of variation with the length scales, which implies different mechanisms. Such length scale dependent deformation and plasticity were analyzed concerning size and interface effects under different stress state.

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

2006 ◽  
Vol 21 (6) ◽  
pp. 1570-1575 ◽  
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.

scholarly journals Experimental Study on the Shear Band of Methane Hydrate-Bearing Sediment

2021 ◽  
Vol 9 (11) ◽  
pp. 1158
Author(s):  
Xiaobing Lu ◽  
Xuhui Zhang ◽  
Fangfang Sun ◽  
Shuyun Wang ◽  
Lele Liu ◽  
...  
Keyword(s):  
Shear Band ◽  
Gas Hydrate ◽  
Methane Hydrate ◽  
Triaxial Compression ◽  
Shear Banding ◽  
Oblique Line ◽  
Shear Bands ◽  
Compression Tests ◽  
Computer Tomography Scan ◽  
Hydrate Saturation

The occurrence of a shear band is often thought as the precursor of failure. To study the initiation of shear banding in gas hydrate-bearing sediments, two groups of triaxial compression tests combined with a CT (computer tomography) scan were conducted by triaxial CT-integrated equipment under two confining pressures and seven hydrate saturations. The macro stress–strain curves and the corresponding CT scanning images of the micro-structure and the distribution of the components were obtained. The geometric parameters of the shear bands were measured based on the CT images at four typical axial strains, respectively. The distribution characteristics of soil particles, water, hydrate and gas were also analyzed. It is shown that the existence of methane hydrate changes the mechanical property of hydrate-bearing sediment from plastic failure to brittle failure when the hydrate saturation is over 13%, which occurs in the range of the tests in this paper. The peak of the deviatoric stress increases with the hydrate saturation. The shear band is in either a single oblique line or inter-cross lines depending on the hydrate saturation, the effective confining pressure and the initial distribution of the gas hydrate. Most of the shear band surfaces are not straight, and the widths of the shear bands are almost non-uniformly distributed.

scholarly journals Simultaneous improvement of plasticity and strength of metallic glasses by tailoring residual stress: Role of stress gradient on shear banding

2021 ◽  
Vol 197 ◽  
pp. 109246
Author(s):  
Lei Zhao ◽  
Dongxue Han ◽  
Shuai Guan ◽  
Xianzheng Lu ◽  
Kangcheung Chan ◽  
...  
Keyword(s):  
Residual Stress ◽  
Metallic Glasses ◽  
Shear Banding ◽  
Stress Gradient

Nucleation and Boundary Layer Growth of Shear Bands in Machining

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Shwetabh Yadav ◽  
Dinakar Sagapuram
Keyword(s):  
Boundary Layer ◽  
Shear Band ◽  
Shear Banding ◽  
Shear Bands ◽  
Critical Shear Stress ◽  
Correlation Method ◽  
Layer Growth ◽  
Image Correlation ◽  
Band Formation ◽  
Stress Criterion

We demonstrate a novel approach to study shear banding in machining at low speeds using a low melting point alloy. In situ imaging and an image correlation method, particle image velocimetry (PIV), are used to capture shear band nucleation and quantitatively analyze the temporal evolution of the localized plastic flow around a shear band. The observations show that the shear band onset is governed by a critical shear stress criterion, while the displacement field around a freshly nucleated shear band evolves in a manner resembling the classical boundary layer formation in viscous fluids. The relevant shear band parameters, the stress at band formation, and local shear band viscosity are presented.

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