Large Isotropic Elastic Deformations: On a Comprehensive Model to Correlate the Theory and Experiments for Incompressible Rubber-Like Materials

• Published in: Journal of elasticity Vol. 153; no. 2; pp. 219 - 244
• Main Author: Anssari-Benam, Afshin
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.03.2023; Springer Nature B.V
• Subjects: Biomechanics; Classical and Continuum Physics; Classical Mechanics; Datasets; Deformation; Elastic deformation; Engineering; Hydrogels; Incompressibility; Materials Science; Mathematical Applications in the Physical Sciences; Mechanical properties; Rubber; Soft tissues; Theoretical and Applied Mechanics; 74-10; Parent model; Non-separable function; Convexity of the iso-energy plots; Strain energy function; 74B20; 74A20; Natural unfilled and filled rubbers
• ISSN: 0374-3535; 1573-2681
• DOI: 10.1007/s10659-022-09982-5

A comprehensive model, i.e., a model that: (i) suitably captures the mechanical behaviour of various types of rubber-like materials; (ii) describes the constitutive behaviour of a subject rubber-like specimen under different deformation modes via a single set of model parameter values, and (iii) is parent to many of the existing models of distinct types, is presented in this paper for application to the finite deformation of incompressible isotropic rubber-like materials. The model breaks away from Rivlin’s principal invariants I i and Valanis-Landel’s separable function of principal stretches λ i representations, and instead adopts a general non-separable functional form W ( λ 1 , λ 2 , λ 3 ) , subject to the incompressibility constraint. By way of example, the application of the model to extant datasets from four types of rubber-like materials that exhibit discernible mechanical behaviours, namely natural unfilled and filled rubbers, hydrogels and (extremely) soft tissue specimens, will be considered. The favourable correlation between the model predictions and the considered experimental datasets, obtained via simultaneous fitting of the model to the data of various deformations, will be demonstrated. It will be shown that most of the landmark models in the literature including the W ( I 1 , I 2 ) form Mooney-Rivlin, the Gent-like limiting chain extensibility, the nonaffine tube and the separable principal stretches-based type Ogden models are all a special sub-set of the presented parent model, and are all recovered from this model. An important implication of the non-separable functional form of the model will be conferred, through a specific dataset, where the predictions of the separable functions prove inherently inadequate. The consequences of these improvements for a more accurate modelling of the finite deformation of incompressible isotropic rubber-like materials will also be discussed.