An Expanding Cavity Model for Indentation Analysis of Shape Memory Alloys

Anuja, J and Narasimhan, R and Ramamurty, U (2020) An Expanding Cavity Model for Indentation Analysis of Shape Memory Alloys. In: Journal of Applied Mechanics, Transactions ASME, 87 (3).

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Abstract

The mechanical and functional responses of shape memory alloys (SMAs), which are often used in small volume applications, can be evaluated using instrumented indentation tests. However, deciphering the indentation test results in SMAs can be complicated due to the combined effects of the non-uniform state of stress underneath the indenter and stress-induced phase transformation. To address this issue, an expanding cavity model (ECM) applicable to spherical indentation of SMAs is developed in this work based on an analytical solution for an internally pressurized hollow sphere. Analytical expressions for key indentation parameters such as the mean contact pressure and size of the transforming zone are obtained, whose validity is evaluated by recourse to finite element simulations and published experimental data for a Ni-Ti alloy. It is shown that the ECM predicts the above parameters reasonably well for indentation strains varying from 0.01 to 0.04. Also, a method is proposed to determine the critical stress required to initiate phase transformation under uniaxial compression based on the application of the ECM to interpret the indentation stress-strain response

Item Type:	Journal Article
Publication:	Journal of Applied Mechanics, Transactions ASME
Publisher:	American Society of Mechanical Engineers (ASME)
Additional Information:	The copyright for this article belongs to the American Society of Mechanical Engineers (ASME)
Keywords:	Binary alloys; Metadata; Metal testing; Nickel alloys; Phase transitions; Shape-memory alloy; Strain; Titanium alloys, Analytical expressions; Expanding cavity models; Finite element simulations; Instrumented indentation; Spherical indentations; Stress induced phase transformations; Stress-strain response; Uni-axial compression, Indentation
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	01 Feb 2023 12:10
Last Modified:	01 Feb 2023 12:10
URI:	https://eprints.iisc.ac.in/id/eprint/79696

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