Adiabatic shear localization in the impact of edge-notched specimens

Roessig, Keith M.; Mason, Joshua

doi:10.1007/bf02325743

“…(4) Extreme deformation within the band: For instance, shear strains in the range of 5-100 have been reported based on marker/grid measurements or postmortem observations of deformed microstructural features [11,45,46]. (5) Very small time scales (<100 ls) are associated with shear band development, as deduced using high-speed imaging experiments [47][48][49]. (6) Local strain rates much larger than nominally applied values:…”

Section: General Features Of Shear Bandsmentioning

confidence: 99%

Shear Bands in Materials Processing: Understanding the Mechanics of Flow Localization From Zener's Time to the Present

Viswanathan

¹

,

Yadav

²

,

Sagapuram

³

2020

Applied Mechanics Reviews

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Shear banding is a material instability in large strain plastic deformation of solids, where otherwise homogeneous flow becomes localized in narrow micrometer-scale bands. Shear bands have broad implications for materials processing and failure under dynamic loading in a wide variety of material systems ranging from metals to rocks. This year marks 75 years since the publication of Zener and Hollomon's pioneering work on shear bands (Zener and Hollomon, J Appl. Phys., 15, 22–32, 1944), which is widely credited with drawing the attention of the mechanics community to shear bands and related localization phenomena. Since this landmark publication, there has been significant experimental and theoretical investigation into the onset of shear banding. Yet, given the extremely small length and time scales associated with band development, several challenges persist in studying the evolution of single bands, postinitiation. For instance, spatiotemporal development of strain fields in the vicinity of a band, crucial to understanding the transition from localized flow to fracture, has remained largely unexplored. Recent full-field displacement measurements, coupled with numerical modeling, have only begun to ameliorate this problem. This article summarizes our present understanding of plastic flow dynamics around single shear bands and the subsequent transition to fracture, with special emphasis on the postinstability stage. These topics are covered specifically from a materials processing perspective. We begin with a semihistorical look at some of Zener's early ideas on shear bands and discuss recent advances in experimental methods for mapping localized flow during band formation, including direct in situ imaging as well as ex situ/postmortem analyses. Classical theories and analytical frameworks are revisited in the light of recently published experimental data. We show that shear bands exhibit a wealth of complex flow characteristics that bear striking resemblance to viscous fluid flows and related boundary layer phenomena. Finally, new material systems and strategies for reproducing shear band formation at low speeds are discussed. It is hoped that these will help further our understanding of shear band dynamics, the subsequent transition to fracture, and lead to practical “control” strategies for suppressing shear band-driven failures in processing applications.

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“…• Very small timescales (< 100 µs) associated with shear band development, as deduced using high-speed imaging experiments [42][43][44].…”

Section: General Features Of Shear Bandsmentioning

confidence: 99%

Shear bands in materials processing: Understanding the mechanics of flow localization from Zener's time to the present

Viswanathan,

Yadav,

Sagapuram

2020

Preprint

0

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Shear banding is a material instability in large strain plastic deformation of solids, where otherwise homogeneous flow becomes localized in narrow micrometer-scale bands. Shear bands have broad implications for materials processing and failure under dynamic loading in a wide variety of material systems ranging from metals to rocks. This year marks nearly 75 years since the publication of Zener and Hollomon's pioneering work on shear bands (C. Zener and J. H. Hollomon, J Appl. Phys., 15:22-32, 1944) which is widely credited with drawing the attention of the mechanics community to shear bands and related localization phenomena. Since this landmark publication, there has been significant experimental and theoretical investigation into the onset of shear banding. Yet, given the extremely small length and time scales associated with band development, several challenges persist in studying the evolution of single bands, post-initiation. For instance, spatiotemporal development of strain fields in the vicinity of a band, crucial to understanding the transition from localized flow to fracture, has remained largely

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“…Different mechanisms have been suggested in the literature for the formation of white etching areas. White etching areas are generally formed due to friction and localised severe deformations during sliding/impact wear [18,49,50]. Such a localised energy conversion can be used to explain the formation of the white etching layers.…”

Section: Subsurface Microstructure Evolutionmentioning

confidence: 99%

Case study: Wear mechanisms of NiCrVMo-steel and CrB-steel scrap shear blades

Abbasi

¹

,

Luo

²

,

Owens³

2018

Wear

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Shear blades are extensively used in the recycling of metal scrap. A comparative study was conducted on used medium carbon NiCrVMo and CrB containing steel scrap shear blades to better understand their wear mechanisms under service conditions. The microstructure and hardness of worn cutting edges and bulk material were characterised by optical microscopy, scanning electron microscopy and microanalysis, X-ray diffraction analysis and macro/micro hardness testing. Moreover, tensile and Charpy impact properties were obtained from the bulk material. Several wear mechanisms were identified in both blades which are categorised in two main groups, i.e. spalling and progressive wear. The progressive wear due to abrasive, adhesive and oxidation wear was observed in both blades. In NiCrVMo-steel blades, spalling and crack propagation from surface/subsurface white etching layers mainly caused the severe wear. However, spalling due to delamination wear and crack propagation from severely deformed subsurface layers was the dominant severe wear mechanism in CrB-steel blades.

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Adiabatic shear localization in the impact of edge-notched specimens

Cited by 15 publications

References 25 publications

Shear Bands in Materials Processing: Understanding the Mechanics of Flow Localization From Zener's Time to the Present

Shear Bands in Materials Processing: Understanding the Mechanics of Flow Localization From Zener's Time to the Present

Shear bands in materials processing: Understanding the mechanics of flow localization from Zener's time to the present

Case study: Wear mechanisms of NiCrVMo-steel and CrB-steel scrap shear blades

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