Analysis of Shear Band Development in a Viscoplastic Double Slip, Single Crystal in Tension

1995 ◽  
Vol 62 (4) ◽  
pp. 827-833 ◽  
Author(s):  
S. Yang ◽  
C. Rey
Keyword(s):  
Shear Band ◽  
Single Crystal ◽  
Shear Banding ◽  
Rate Sensitivity ◽  
Shear Localization ◽  
Rigid Plastic ◽  
Band Formation ◽  
Linearized Stability ◽  
Slow Progression ◽  
Crystal Model

Using an idealized planar single crystal model undergoing symmetrical double slip in tension, the effect of rate sensitivity on shear band initiation and on shear band development is analysed. The behavior of the crystal is assumed to be rigid-viscoplastic. By analysing the kinematics and statics of shear banding, the deformation modes involving shear banding pattern are formulated. By a linearized stability analysis, the critical condition for shear band initiation is obtained. To study shear band development, the formulated constitutive equations are numerically solved, and the maximum value of the localized shear is predicted. The results show three different stages of shear band development. The first corresponds to a slow progression of shear localization in the band, the second to a rapid shear localization accompanied with an unloading of surrounding material, and the third to a resumption of deformation in the surrounding material and to a progressive saturation of the shear band. All three stages depend strongly on rate sensitivity, especially the first stage which does not exist in the rigid-plastic case. Even very small rate sensitivity can delay significantly or even preclude the shear band formation. Finally a discussion of the results illustrates how a macroscopic shear band forms and propagates.

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.

scholarly journals Identifying structural signatures of shear banding in model polymer nanopillars

Soft Matter ◽  
2019 ◽  
Vol 15 (22) ◽  
pp. 4548-4561 ◽  
Author(s):  
Robert J. S. Ivancic ◽  
Robert A. Riggleman
Keyword(s):  
Machine Learning ◽  
Shear Band ◽  
Defect Structure ◽  
Amorphous Materials ◽  
Shear Banding ◽  
Shear Band Formation ◽  
Learning Methods ◽  
Band Formation ◽  
Mesoscale Models ◽  
Machine Learning Methods

Shear band formation often proceeds fracture in amorphous materials. While mesoscale models postulate an underlying defect structure to explain this phenomenon, they do not detail the microscopic properties of these defects especially in strongly confined materials. Here, we use machine learning methods to uncover these microscopic defects in simulated polymer nanopillars.

The Phenomenon of Shear Strain Localization in Dynamic Viscoplasticity

1992 ◽  
Vol 45 (3S) ◽  
pp. S46-S61 ◽  
Author(s):  
T. G. Shawki
Keyword(s):  
Shear Band ◽  
Rate Sensitivity ◽  
Shear Band Formation ◽  
Viscoplastic Material ◽  
Flow Localization ◽  
Unified Framework ◽  
Band Formation ◽  
Shearing Deformation ◽  
Computational Procedures ◽  
The One

This article addresses shear flow localization during high rates of deformation of thermal viscoplastic materials. An overview of several efforts towards an improved understanding of shear band formation is given. This paper aims at extracting a unified framework towards the analysis of shear band formation for the considered class of deformations. For this purpose, we present a number of rigorous exact solutions for the one–dimensional simple shearing deformation of a general class of thermal viscoplastic material response. These solutions are used as benchmarks for the validation of both analytical and computational procedures. The interactive roles of inertia, rate–sensitivity, heat conduction, perturbation geometry, boundary conditions, thermal softening, strain hardening and constitutive description as regards the initiation and further intensification of flow localization are thoroughly addressed. We also examine the delicate questions concerning the notion of shear localization and the related mathematical characterization, length and time scales as well as the connection between localization and catastrophic failure.

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.

Analysis of serrations and shear bands fractality in UFGs

2015 ◽  
Vol 24 (1-2) ◽  
pp. 1-9 ◽  
Author(s):  
Aggelos C. Iliopoulos ◽  
Nikolaos S. Nikolaidis ◽  
Elias C. Aifantis
Keyword(s):  
Shear Band ◽  
Shear Banding ◽  
Shear Bands ◽  
Ultrafine Grain ◽  
Strain Rates ◽  
Stress Strain ◽  
Band Formation ◽  
Serrated Flow ◽  
Multiple Shear Band ◽  
First Case

AbstractTsallis nonextensive statistics is employed to characterize serrated flow, as well as multiple shear band formation in ultrafine grain (UFG) size materials. Two such UFG materials, a bi-modal Al-Mg alloy and a Fe-Cu alloy, were chosen. In the first case, at low strain rates serrated flow emerges as recorded in the stress-strain graphs, whereas at high strain rates, extensive shear banding occurs. In the second case, multiple shear banding is the only mechanism for plastic deformation, but serrations in the stress-strain graph are not recorded. The analysis aims at the estimation of Tsallis entropic index qstat (stat denotes stationary state), as well as the estimation of fractal dimension. The results reveal that the distributions of serrations and shear bands do not follow Gaussian statistics as implied by Boltzmann-Gibbs extensive thermodynamics, but are approximated instead by Tsallis q-Gaussian distributions, as suggested by nonextensive thermodynamics. In addition, fractal analysis of multiple shear band images reveals a (multi)fractal and hierarchical profile of the spatial arrangement of shear bands.

Analysis of Localized Shear Band Formation and Post Shear Banding in FCC Single Crystals

2000 ◽  
Vol 2000.1 (0) ◽  
pp. 23-24
Author(s):  
Shokichi KANNO ◽  
Koichi ITO ◽  
Jun NITTA ◽  
Yoshihiro KAMADA ◽  
Taketoshi SAGAWA
Keyword(s):  
Shear Band ◽  
Single Crystals ◽  
Shear Banding ◽  
Shear Band Formation ◽  
Band Formation

Analytical Modeling of Shear Localization in Orthogonal Cutting Processes

2021 ◽  
pp. 1-45
Author(s):  
Mohammadreza Fazlali ◽  
Mauricio Ponga ◽  
Xiaoliang Jin
Keyword(s):  
Shear Band ◽  
Orthogonal Cutting ◽  
Shear Bands ◽  
Chip Morphology ◽  
High Strength ◽  
Shear Localization ◽  
Shear Band Formation ◽  
Workpiece Material ◽  
Band Formation ◽  
Cutting Processes

Abstract This paper presents an analytical thermo-mechanical model of shear localization and shear band formation in orthogonal cutting of high-strength metallic alloys. The deformation process of the workpiece material includes three stages: homogeneous deformation, shear localization, and chip segmentation. A boundary layer analysis is used to analytically predict the temperature, stress, and strain rate variations in the primary shear zone associated with the shear localization. The predictions of shear band spacing and width from the proposed model are verified by experimental characterization of the chip morphology. The rolling of shear bands on the tool rake face is discussed from the experimental observations. The cutting tool temperature, which is influenced by the heat generated during the shear band formation, is simulated and compared with the finite element simulations. The proposed analytical model reveals the fundamental mechanism of the complete shear localization process in orthogonal cutting, and predicts the stress and temperature variations with high computational efficiency.

Experimental and Numerical Study of Intense Shear Banding for Al-Alloy under Uniaxial Tension

2005 ◽  
Vol 6-8 ◽  
pp. 737-744 ◽  
Author(s):  
Xin Jian Duan ◽  
Mukesh K. Jain ◽  
M. Bruhis ◽  
David S. Wilkinson
Keyword(s):  
Shear Band ◽  
Uniaxial Tension ◽  
Numerical Study ◽  
Shear Banding ◽  
Gauge Length ◽  
Image Correlation ◽  
Al Alloy ◽  
Band Formation ◽  
Full Field ◽  
Intense Shear

The occurrence of intense shear band is a prelude to failure in many Al-sheet materials. In the present study, a full field optical system measurement technique (digital image correlation) and the finite element method are used to characterize the sequence of deformation in uniaxial tension before and after the intense shear band formation in AA6111-T4. The results indicate good agreement between the measurement and the predictions in terms of shear band width, strain distribution along the gauge length and the failure mode.

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