Bending instabilities of soft tissues

TL;DR

This paper investigates the bending instabilities in soft tissues and rubber, revealing critical stretch ratios before bifurcation, with implications for understanding tissue behavior under large deformations.

Contribution

It provides a comparative analysis of bending instabilities across different soft tissue and rubber models, highlighting the influence of strain-stiffening effects on critical stretch ratios.

Findings

Rubber models show a critical stretch ratio of 0.56, allowing 44% contraction.

Artery models predict a higher critical stretch ratio of 0.73, allowing 27% contraction.

Experimental data suggest earlier instabilities in pig skin tissues.

Abstract

Rubber components and soft tissues are often subjected to large bending deformations "in service". The circumferential line elements on the inner face of a bent block can contract up to a certain critical stretch ratio lambda_cr (say) before bifurcation occurs and axial creases appear. For several models used to describe rubber, it is found that lambda_cr = 0.56, allowing for a 44% contraction. For models used to describe arteries it is found, somewhat surprisingly, that the strain-stiffening effect promotes instability. For example, the models used for the artery of a 70 year old human predict that lambda_cr = 0.73, allowing only for a 27% contraction. Tensile experiments conducted on pig skin indicate that bending instabilities should occur even earlier there.