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Dynamic shear fracture toughness and failure characteristics of Ti–6Al–4V alloy under high loading rates

Xu, Z; Han, Y; Fan, C; He, X; Tan, PJ; Huang, F; (2021) Dynamic shear fracture toughness and failure characteristics of Ti–6Al–4V alloy under high loading rates. Mechanics of Materials , 154 , Article 103718. 10.1016/j.mechmat.2020.103718. Green open access

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Abstract

A novel 2-bar/double-shear impact (2B/2SI) loading technique is used to study the dynamic mode II (shear) fracture characteristics of Ti–6Al–4V. The new specimen design, to be used in combination with a standard split Hopkinson pressure bar, circumvent classical limitations associated with conventional one-point impact methods. This paper presents a combined experimental-numerical approach to determining the mode II fracture toughness of Ti–6Al–4V for a broad range of loading rates between 1.10 × 10^{−2}- 4.98 × 10^{7} (MPa, m^{1/2}s^{−1}). Results showed only a slight initial increase in toughness, which increases abruptly with loading rates beyond 10^{6} (MPa, m^{1/2}s^{−1}). Fractographic examination showed distinctively different mechanisms in operation at the microscale, depending on the rate of loading. Failure is through a brittle-ductile, mixed-mode fracture under quasi-static conditions; by contrast, the fracture surface exhibited fractographic features of adiabatic shear bands (ASB) and material melting/re-solidification under dynamic conditions. High-speed photography showed that both dynamic shear fracture (DSF) and ASB occurred during the same loading process. Interactions between DSF and ASB were observed to influence the dominant failure mechanism of the material at high loading rates.

Type: Article
Title: Dynamic shear fracture toughness and failure characteristics of Ti–6Al–4V alloy under high loading rates
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.mechmat.2020.103718
Publisher version: https://doi.org/10.1016/j.mechmat.2020.103718
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher's terms and conditions.
Keywords: Dynamic fracture, Shear (mode II) fracture, Adiabatic shear band, High strain rate, Hopkinson bar
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/10118976
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