MEASUREMENT OF YOUNG’S MODULUS AND SHEAR MODULUS OF PLYWOOD BY FLEXURAL VIBRATION TEST AND INFLUENCE OF SPECIMEN SHAPE

Abstract

 In this study, Young’s modulus and shear modulus of plywood were measured by flexural vibration test. The width of the plywood was gradually changed, and the influence of the specimen shape was investigated. In addition, static torsion tests were conducted on the same specimens, and the obtained shear modulus was compared with the edgewise shear modulus obtained from the flexural vibration tests. The results of the flexural vibration tests showed that when the specimen was wide, it was difficult to measure multiple resonance frequencies of flexural vibration modes, regardless of whether the impact was applied in the in-plane or out-of-plane direction. However, when the specimen’s width was less than a quarter of its length, resonance frequencies of the first to fifth flexural vibrations could be easily measured. When vibration was applied in the in-plane direction, as the width of the specimen decreased, Young’s modulus increased and shear modulus decreased. On the other hand, when vibration was applied in the out-of-plane direction, Young’s modulus and shear modulus did not change significantly even when the width of the specimen was changed. As a result of comparing the edgewise shear modulus obtained in the flexural vibration test and the shear modulus obtained in the static torsion test, there was no significant difference between the two values for specimens whose width was one-eighth of their length.