Objective   To provide a new method for the online non-destructive determination for modulus of elasticity (MOE) in two main directions of a full-size plywood panel, the vibration determination for MOE in two main directions of a full-size plywood panel simply supported on two opposite sides was studied.

  Method   20 pieces of full-size plywood panels with four different thicknesses were used as study objects. The modal sensitivity analysis and experimental modal analysis of full-size plywood panels simply supported on two opposite sides were performed using finite element software COMSOL Multiphysics and the PULSE vibration test system. The frequencies of needed modes were obtained by a vibration detection method for MOE of the full-size plywood panel proposed in this study, then incorporated into a vibration detection algorithm of the dynamic MOE in two main directions of a full-size plywood panel. In order to verify the accuracy of the dynamic MOE values measured, the static MOE values in two main directions of a full-size plywood panel were also obtained through three-point bending test.

  Result   The frequencies of free vibration modes (2, 0) and (2, 2) as the first and seventh modes in the first nine modes of the full-size plywood panel were conducted for calculation of MOE in the length and width directions of the panels, respectively. The results revealed that thickness variation had no effect on the ordering of the first nine modes for the full-size plywood panels. The dynamic MOE values were greater than the static ones of the full-size plywood panels, and there existed inhomogeneity of mechanical properties for the full-size plywood panels with the same thickness. Dynamic MOE had a strong correlation with static MOE in both length and width directions of the full-size plywood panels (R² = 0.907 and 0.655, respectively).

  Conclusion   It is feasible for determining MOE of a full-size plywood panel based on two-opposite-side vibration and vibration detection algorithm for MOE.