In-plane shear modulus of extruded polystyrene foam measured by the torsional vibration, square-plate twist and simple shear methods

In this work, the in-plane shear modulus of extruded polystyrene foam was obtained using the torsional vibration and square-plate twist methods on square plate specimens with various lengths and performing subsequent numerical analysis on the test data. Additionally, the ASTM C273/273M-11 simple shear tests were conducted and the results were compared with those obtained from the torsional vibration and square-plate twist methods. The in-plane shear modulus value obtained from the torsional vibration and square-plate twist methods was often dependent on the specimen configuration. Nevertheless, the in-plane shear modulus value could be obtained effectively by introducing a simple correction coefficient determined from the numerical analysis. In contrast, the in-plane shear modulus value obtained from the simple shear test was often lower than those obtained from the torsional vibration and square-plate twist methods.