ABSTRACT
This chapter describes results obtained from tests using an axi-symmetric bubble inflation rig. The rig allows the determination of real time stress/strain data for thin elastomeric sheets subjected to cyclic loading by bubble inflation. The potential of the rig to determine other multiaxial viscoelastic properties of materials using different inflation media has led to a widening of the programme. Non strain crystallising elastomers exhibit higher fatigue lives when pre-stressed uniaxially. One of the aims of the research is to investigate whether this phenomenon is replicated for multiaxial fatigue. Bubble inflation is assumed to comply with theory for applying pressure to a thin spherical shell structure possessing negligible bending stiffness, alternatively described as membrane theory. Until the control of the machine assimilates constant true stress amplitudes, comparing dynamic stored energy and change in complex modulus for specimens fatigued using bubble inflation with the results achieved in uniaxial tests is of limited benefit.
