Her Majesty the Queen in Right of the Province of Alberta, as

Andrew W Porter

Lars Bach

The present invention provides an apparatus and method for establishing a measure of the modulus of elasticity of a wood panel. The apparatus comprises a support frame having a triangular array of panel support points provided thereon. A load cell, in combination with one support point, is interconnected to a frequency counter. This assembly is functional to determine the weight and vibration frequency of a dropped panel. A panel lifting assembly is provided to raise and drop the panel, thereby causing it to vibrate at its natural frequency. In a process aspect, the invention involves supporting the panel at three triangularly arranged support points, raising the panel at the apex end, and dropping the panel to cause it to vibrate at its resonant frequency, and computing a measure of stiffness from the measurements made.

Transverse vibration apparatus for grading wood panels

A non-destructive method and apparatus is provided for testing a wood panel, such as a sheet of plywood, to establish values which may be used in calculating a measure of the modulus of elasticity (MOE) for the panel. The invention involves supporting the bottom surface of the panel horizontally with two spaced parallel rollers and contacting the top surface of the panel with a pivotally mounted loading bar which is adapted to apply linear loading to the panel substantially uniformly across its width, even though the panel may be warped or bent. The loading bar is biased by a double-acting cylinder so as to apply a first load and then, in quick succession, a second incremental load. The two loads are selected so as to fall on the substantially linear portion of the load deflection curve for the panel. The magnitudes of the two loads are measured with suitable means, such as a load cell. The extension or distance moved by the cylinder in applying the incremental load is known or measured. With the two loadings and the incremental deflection established, one can calculate, using standard formulae, a value which is found to closely approximate the MOE.

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Richmond, Canada

Andrew W Porter