Limitations of Viscoelastic Constitutive Models for Carbon-Black Reinforced Rubber in Medium Dynamic Strains and Medium Strain Rates.

Francesca Carleo,James Busfield,Roly Whear,Ettore Barbieri

doi:10.3390/polym10090988

Abstract

Modelling the viscoelastic behavior of rubber for use in component design remains a challenge. Most of the literature does not consider the typical regimes encountered by anti-vibration devices that are deformed to medium dynamic strains (0.5 to 3.5) at medium strain rates (0.5/s to 10/s). Previous studies have either focused on the behaviour at small strains and small strain rates or in fast loading conditions that result in low cycle fatigue or tearing phenomena. There is a lack of understanding of the dynamic response of natural rubber suspension components when used in real vehicle applications. This paper presents a review of popular viscoelastic nonlinear constitutive models and their ability to model the mechanical behaviour of typical elastomer materials such as Natural Rubber (NR) incorporating different PHR (Parts per Hundred Rubber, XX) of carbon black. The range of strain and strain rate are typical for the materials used in rubber suspensions when operating in severe service operating conditions, such as over rough terrain or over pot-holes. The cyclic strain is applied at different amplitudes and different strain rates in this medium strain range. Despite the availability of many models in the literature, our study reports that none of the existing models can fit the data satisfactorily over a wide range of conditions.

Highlights

Research into the viscoelastic properties of rubberlike materials has attracted much attention in the automotive [1,2,3,4] and biomedical sectors [5,6,7,8,9]
The cyclic strain is applied at different amplitudes and different strain rates in this medium strain range
Two different theoretical philosophies exist in formulating material models: the phenomenological and the micro-mechanical approach

Summary

Introduction

Research into the viscoelastic properties of rubberlike materials has attracted much attention in the automotive [1,2,3,4] and biomedical sectors [5,6,7,8,9]. The observed properties include significant nonlinearity, hysteresis, cyclic stress softening and induced anisotropy during cyclic deformation. Two different theoretical philosophies exist in formulating material models: the phenomenological and the micro-mechanical approach. The first is based on direct observation and the accurate measurement of the mechanical response of the rubber with curve-fitting of the experimental data or derivation of the strain energy function from a consideration of changes to the molecular conformation. The second, micro-mechanical approach, consists of the study of constituent materials and how they interact with each other [10,11]. The models can include atoms, molecules or the entire polymer chain. The multiscale nature of the polymers is reflected in this multiscale analysis, which can be based on different computational methods for specific length and time scales: quantum

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Discussion

Conclusion