Inflation Technique Optimization for an Elastomer Biaxial Characterization

Abstract : It can be extremely useful to know biaxial properties of materials like elastomers used for mechanical applications or thermoplastics for the simulation of injection stretch/blow moulding or thermoforming processes. The biaxial stress-strain data of such materials can be obtained using a bubble-inflation-technique. A circular membrane is clamped at the rim and inflated by a pressure applied to one of its side. The inflation of the circular membrane is recorded using a CCD video camera and the blowing pressure by a pressure sensor. This technique was applied to the determination of an elastomer rheological behaviour, and will be adapted for thermoplastics (including a heating device). First, an experimental setup was carried out, using a thickness measurement magnetic probe, in order to validate rheometer results. Circonferential biaxial Cauchy stress-elongation curve of the elastomer studied was compared with the uniaxial stress-elongation curve.