INFLUENCE OF THE SPECIMEN DEPTH TO LENGTH RATIO AND LAMINATION CONSTRUCTION ON YOUNG'S MODULUS AND IN-PLANE SHEAR MODULUS OF PLYWOOD MEASURED BY FLEXURAL VIBRATION

In this study, the Young's modulus and the in-plane shear modulus of 3-, 5-, and, 7-ply Lauan wood (Shorea sp.) were determined by conducting a flexural vibration test with various specimen depth to length ratios and performing a subsequent finite element analysis (FEA). The length and depth directions of the specimen used for the vibration test coincided with the length/width and width/length directions of the plywood panel. The results obtained from the experiment and FEA revealed that the influence of specimen configuration and lamination construction did not significantly affect the measurement of the Young's modulus. However, the results suggested that the in-plane shear modulus decreased as the depth to length ratio of the specimen decreased. The FEA result suggested that this decreasing tendency is more pronounced as the ply number decreases and the thickness of the plywood increases. A statistical analysis on the experimental results suggested that the length of the specimen must be less than 10 times the depth to reduce the influence of specimen configuration on the measured value of the in-plane shear modulus.