Evaluation of the Shear Modulus of Paperboard Measured from a Torsional Vibration Test

Abstract

In this study, in-plane and out-of-plane shear moduli of paperboard were obtained from free-free torsional vibration (FFTV) tests under various specimen configurations. Independently of the torsional vibration tests, 45° off-axis tensile tests were conducted to measure the in-plane shear modulus, and the obtained results were compared with those by the torsional vibration tests. The results are summarized as follows: (1) When a single specimen was used, obtaining the in-plane shear modulus from the FFTV test accurately was difficult because of the strong orthotropy in the paperboard. However, the accuracy was improved when specimens with various widths were used. (2) The in-plane shear modulus obtained from the FFTV tests was significantly greater than that obtained from the 45° off-axis tensile test because of the effect of the lamination construction of the paperboard. (3) The out-of-plane shear modulus was considerably lower than the in-plane shear modulus. The inaccuracy in measuring the in-plane shear modulus using a single specimen was enhanced by the low value of the out-of-shear modulus. (4) The out-of-plane shear modulus in the plane defined by the machine and thickness directions was significantly greater than that in the plane defined by the cross-machine and thickness directions.