Design of a flat plate specimen suitable for biaxial tensile tests on polymer materials

Since the introduction of fibre-reinforced polymer composites there has been a surge in the use of adhesives for joints and repairs, and polymer resins as the matrix material for fibre-reinforced composites. The failure mechanisms of these materials have been studied by many researchers; however, there is little accurate experimental data under tension-tension loading published. This is due to the lack of a standard specimen design to perform these tests. The authors propose a flat plate specimen design that has been shown to overcome some of the difficulties presented in literature. A series of tests with this specimen configuration were conducted under varying biaxial loading conditions. The results are plotted in the tension-tension quadrant of the materials failure envelope. For the two polymer materials tested; a linear truncation within the first quadrant of the failure envelope was found.