Open Access

ARTICLE

On the Indentation of a Chemically-treated Polymeric Membrane

by A. P. S. Selvadurai¹, Q. Yu²

1 Corresponding author. William Scott Professor and James McGill Professor. Department of Civil Engineering and Applied Mechanics, McGill University, 817 Sherbrooke Street West, Montreal, QC, Canada H3A 2K6 (E-mail: patrick.selvadurai@mcgill.ca). Tel: +1 514 398 6672; fax: +1 514 398 7361
2 Doctoral student

Computer Modeling in Engineering & Sciences 2005, 9(1), 85-110. https://doi.org/10.3970/cmes.2005.009.085

Abstract

A characteristic feature of a polymeric material such as PVC is its hyperelasticity or the ability to experience large strains prior to failure. The exposure of PVC to chemicals such as acetone and ethanol results in embrittlement or the loss of the hyperelasticity property. In this paper, we examine the mechanical behaviour of a PVC membrane that has been exposed to ethanol. Due to leaching of the plasticizer, the constitutive response of the PVC changes from a hyperelastic material to a hardened material that displays dominant yield behaviour and particularly one that is capable of experiencing post-yield large strains and strain-rate effects. A constitutive model is developed to describe the mechanical behaviour of the PVC subjected to ethanol exposure. This constitutive model is implemented in a computational code to examine the problem of the mechanical behaviour of a chemically-treated membrane that is fixed along a circular boundary and loaded by a rigid spherical indentor. Both axisymmetric and asymmetric off-axis indentation tests are performed on the chemically-treated PVC. The load-displacement responses of the indentor as well as the profiles of the chemically-treated PVC membrane during indentation are used to assess the predictive capabilities of the constitutive model.

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