Poisson's ratio and compressibility of arterial wall - Improved experimental data reject auxetic behaviour

Poisson's ratio of fibrous soft tissue is analyzed in this paper on the basis of direct experimental measurements of porcine arterial wall layer under uniaxial tension and immersed in tempered saline bath. The current study follows the previously published testing methodology but with a new totally redesigned testing apparatus allowing more credible and precise evaluation of arterial wall behaviour. The new results confirm most of previous findings focused on positivity/negativity of Poisson's ratio playing a crucial role in (in)validation aspects of some constitutive models widely used in recent computational vascular mechanics. The effect of frozen & thawed conditions is also evaluated in comparison with fresh specimens. The in-plane Poisson's ratio of arterial wall was identified in the range of 0.3-0.4, whereas its out-of-plane component is much higher ranging from 0.5 to 0.7. These results contrast with predictions of some frequently used constitutive models. The volumetric (in)compressibility of arterial specimens is also analyzed, quantified and discussed in the paper, as a key property of soft tissues closely related to the topic of their constitutive modelling.