An experimental technique for determining biaxial fatigue lifetimes in biomedical elastomers

A novel test apparatus was developed to determine fatigue lifetimes of elastomeric materials. Thin elastomeric sheets (membranes) are biaxially fatigued while contained within a temperature controlled liquid environment. Membranes are displaced in a smooth sinusoidal motion by pumping the surrounding fluid through the equipmentʹs inner cells. An electrical signal (AC) passes through the membrane during fatigue and is used to monitor changes in the elastomerʹs physical characteristics. In addition, the test cell is designed to allow optical observation of the membrane throughout the fatiguing process. Thus the design results in a test rig apparatus that permits failure determination by both material property changes and obvious fracture. Cyclic fatigue frequencies range from 0.2 to 1.2 Hz.