The Description of Anisotropic Mechanical Behaviour

An oriented polymer is in the strictest terms an anisotropic non-linearly viscoelastic material. A comprehensive understanding of anisotropic mechanical behaviour is therefore a very considerable task. In this chapter, we will restrict the discussion to cases where the 

The mechanical properties of an anisotropic elastic solid for small sriains are defined by 

In an elastic material, the presence of symmetry elements leads to a reduction in the number of independent elastic constants and corresponding reductions will be assumed for anisotropic linear viscoelastic behaviour, although there is not enough experimental evidence to eonfirm that exactly the same mles hold in every case [2]. 

Mechanical Properties of Solid Polymers, Third Edition. I. M. Ward and J. Sweeney. 2013 John Wiley Sons, Ltd. PubUshed 2013 by John Wiley Sons, Ltd. 

There are two important points to emphasise regarding the description of data 1. In practice an abbreviated notation is often used in which 

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