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.

[1]  H. Yoshihara.  Measurement of the In-Plane Shear Modulus of Plywood by Tension Test of [±45] Off-Axis Specimen , 2011 .

[2]  K. Murata,et al.  Determination of Young's modulus and shear modulus by means of deflection curves for wood beams obtained in static bending tests , 2007 .

[3]  H. Yoshihara.  Edgewise shear modulus of plywood measured by square-plate twist and beam flexure methods , 2009 .

[4]  R. Hearmon,et al.  The fundamental frequency of vibration of rectangular wood and plywood plates , 1946 .

[5]  Hiroshi Yoshihara,et al.  MEASUREMENT OF THE YOUNG’S MODULUS AND SHEAR MODULUS OF IN-PLANE QUASI-ISOTROPIC MEDIUM-DENSITY FIBERBOARD BY FLEXURAL VIBRATION , 2011 .

[6]  AIWSc. Y. H. Chui Ph. D.,et al.  Influence of rotatory inertia, shear deformation and support condition on natural frequencies of wooden beams , 2005, Wood Science and Technology.

[7]  L. Brancheriau.  Influence of cross section dimensions on Timoshenko’s shear factor – Application to wooden beams in free-free flexural vibration , 2006 .

[8]  Henri Baillères,et al.  Use of the Partial Least Squares Method with Acoustic Vibration Spectra as a New Grading Technique for Structural Timber , 2003 .

[9]  R. Hearmon,et al.  Elasticity of Wood and Plywood , 1948, Nature.

[10]  T. Okano,et al.  Examination of the method of measuring the shear modulus of wood baced on the Timoshenko theory of bending , 1996 .

[11]  N. Sobue.  Instantaneous Measurement of Elastic Constants by Analysis of the Tap Tone of Wood : Application to flexural vibration of beams , 1986 .

[12]  F. Divos,et al.  Determination of shear modulus on construction size timber , 1998, Wood Science and Technology.

[13]  S. Timoshenko,et al.  LXVI. On the correction for shear of the differential equation for transverse vibrations of prismatic bars , 1921 .

[14]  Ying Hei Chui,et al.  Influence of rotatory inertia, shear deformation and support condition on natural frequencies of wooden beams , 1990 .

[15]  R. Hearmon,et al.  The influence of shear and rotatory inertia on the free flexural vibration of wooden beams , 1958 .

[16]  L. Brancheriau,et al.  Natural vibration analysis of clear wooden beams: a theoretical review , 2002, Wood Science and Technology.

[17]  Tetsuya Nakao,et al.  Evaluation of Modulus of Rigidity By Dynamic Plate Shear Testing , 2007 .

[18]  H. Yoshihara.  Poisson's ratio of plywood measured by tension test , 2009 .

[19]  Mehran Roohnia,et al.  Nondestructive detection of the effect of drilling on acoustic performance of wood , 2011, BioResources.