On the bursting of a balloon

Abstract

The tear behaviour during the bursting of natural rubber balloons under 100%, 300% and 400% biaxial strain has been investigated in detail by means of high speed cinematography. The tear velocity was observed to be approximately three times the finite elastic wave velocity during unloading (the retraction velocity), in each case. A theoretical analysis is provided for the case of uniform biaxial strain, relevant to the present work, leading to formulae for the retraction and elastic wave velocities. Observed retraction velocities were consistent with theoretical predictions based on the static stress-strain curve in biaxial tension. It is suggested that tear velocity is determined by the elastic properties of the rubber in a localised region of high strains just around the tip.