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Proceedings Paper

Experiments to find constitutive relation for materials undergoing large deformation
Author(s): H. Hariharaputhiran; U. Saravanan
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Paper Abstract

In this article, details about state of art custom built experimental set up to perform biaxial tests on thin sheets made of polymers or soft biological tissues is presented. This displacement controlled set up can apply and measure loads ranging from 0.01 N to 100 N. Then, the uniform or non-uniform surface deformation is determined from tracking a set of markers in 3D space using 2 CCD cameras. Using this setup both elastic and viscoelastic properties of the material could be characterized and the assumption of incompressibility verified. Following Rivlin and Saunders,1 the stored energy corresponding to vulcanized rubber, for stretch ratios less than 1.5, is found by systematically varying one of the variables in the stored energy function. This is achieved by performing biaxial extension tests in which the stretch ratio along one direction is held constant but varied between protocols and the stretch ratio in the perpendicular direction is increased gradually from 1 to 1.5. Then, the predictive capability of the stored energy function is examined by comparing its prediction for the uniaxial extension test with the actual experimental results. However, unlike Rivlin and Saunders, the stored energy is allowed to be either a function of the invariants of left Cauchy-Green stretch tensor (Rivlin2) or the invariants of Hencky strain (Criscione et al3) or the principal stretch ratios (Ogden4). None of the stored energy functions evaluated in this study is able to consistently predict the available experimental data.

Paper Details

Date Published: 14 April 2010
PDF: 10 pages
Proc. SPIE 7522, Fourth International Conference on Experimental Mechanics, 75223W (14 April 2010); doi: 10.1117/12.851759
Show Author Affiliations
H. Hariharaputhiran, Indian Institute of Technology Madras (India)
U. Saravanan, Indian Institute of Technology Madras (India)

Published in SPIE Proceedings Vol. 7522:
Fourth International Conference on Experimental Mechanics
Chenggen Quan; Kemao Qian; Anand Krishna Asundi; Fook Siong Chau, Editor(s)

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