Axisymmetric necking versus Treloar–Kearsley instability in a hyperelastic sheet under equibiaxial stretching

Fu

doi:10.1177/10812865211072897

Axisymmetric necking versus Treloar–Kearsley instability in a hyperelastic sheet under equibiaxial stretching

Fu

Authors

Yibin Fu y.fu@keele.ac.uk

Abstract

We consider bifurcations from the homogeneous solution of a circular or square hyperelastic sheet that is subjected to equibiaxial stretching under either force- or displacement-controlled edge conditions. We derive the condition for axisymmetric necking and show, for the class of strain-energy functions considered, that the critical stretch for necking is greater than the critical stretch for the Treloar-Kearsley (TK) instability and less than the critical stretch for the limiting-point instability. An amplitude equation for the bifurcated necking solution is derived through a weakly nonlinear analysis and is used to show that necking initiation is generally sub-critical. Abaqus simulations are conducted to verify the bifurcation conditions and the expectation that the TK instability should occur first under force control, but when the edge displacement is controlled, the TK instability is suppressed, and it is the necking instability that will be observed. It is also demonstrated that axisymmetric necking follows a growth/propagation process typical of all such localization problems.

Acceptance Date	Dec 1, 2021
Publication Date	Feb 1, 2022
Journal	Mathematics and Mechanics of Solids
Print ISSN	1081-2865
Publisher	SAGE Publications
DOI	https://doi.org/10.1177/10812865211072897
Keywords	Necking; Treloar-Kearsley instability; equibiaxial tension; elastic localization; nonlinear elasticity
Publisher URL	https://journals.sagepub.com/doi/10.1177/10812865211072897