A mechanism for shear band formation in the high strain rate torsion test

A numerical study of a one-dimensional model of the high strain-rate torsion test shows that a moving boundary of rigid unloading, starting from the ends of the thin-walled tubular specimen, is a plausible mechanism for adiabatic shear band formation during the test. Even though the dimensionless thermal diffusivity parameter is very small, the moving boundary is due to heat transfer from the specimen through its ends, which are assumed to be isothermal heat sinks. The mathematical model is based on a physical model of thermoelastic-plastic flow and a phenomenological Arrhenius model for the plastic flow surface. The numerical technique used is the semi-discretization method of lines.

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Dynamic Mechanical Properties and Microstructure of an (Al0.5CoCrFeNi)0.95Mo0.025C0.025 High Entropy Alloy

Entropy ◽

10.3390/e21121154 ◽

2019 ◽

Vol 21 (12) ◽

pp. 1154

Author(s):

Bingfeng Wang ◽

Chu Wang ◽

Bin Liu ◽

Xiaoyong Zhang

Keyword(s):

Mechanical Properties ◽

Shear Band ◽

High Strain Rate ◽

Strain Rate ◽

High Strain ◽

Dynamic Mechanical Properties ◽

High Entropy Alloy ◽

Face Centered Cubic ◽

High Entropy ◽

Dynamic Mechanical

The dynamic mechanical properties and microstructure of the (Al0.5CoCrFeNi)0.95Mo0.025C0.025 high entropy alloy (HEA) prepared by powder extrusion were investigated by a split Hopkinson pressure bar and electron probe microanalyzer and scanning electron microscope. The (Al0.5CoCrFeNi)0.95Mo0.025C0.025 HEA has a uniform face-centered cubic plus body-centered cubic solid solution structure and a fine grain-sized microstructure with a size of about 2 microns. The HEA possesses an excellent strain hardening rate and high strain rate sensitivity at a high strain rate. The Johnson–Cook plastic model was used to describe the dynamic flow behavior. Hat-shaped specimens with different nominal strain levels were used to investigate forced shear localization. After dynamic deformation, a thin and short shear band was generated in the designed shear zone and then the specimen quickly fractured along the shear band.

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Numerical Simulation of Hot High Strain Rate Torsion Tests for Al-Based Alloys

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.822.66 ◽

2019 ◽

Vol 822 ◽

pp. 66-71

Author(s):

Anton Naumov ◽

Anatolii Borisov ◽

Anastasiya Y. Doroshchenkova

Keyword(s):

Numerical Simulation ◽

High Strain Rate ◽

Strain Rate ◽

Visual Analysis ◽

Physical Simulation ◽

High Strain ◽

Torsion Test ◽

Strain Rates ◽

Deform 3D

The present research describes the comparison of numerical and physical simulation of hot high strain rate torsion tests for Al-based alloys in order to clarify the accuracy of calculations using basic grades of materials in Deform-3DTM software. A comparative visual analysis of the results is presented. Obtained data on the distribution of temperatures, strains, stresses and strain rates during the torsion test are discussed.

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