4.1 This test method is most useful for determining the moduli of rigidity of orthotropic materials for which moduli of rigidity cannot be computed from elastic moduli and Poisson's ratios. The shear modulus determined by this method appears in the equation governing the bending of a plate. This is the modulus that is needed in discussing the deflection and buckling of plates.

Note 2: Test Methods D2718 describes a plate method for determination of modulus of rigidity of structural panels.

1.1 This test method covers determination of the shear modulus of wood-based structural panels associated with shear distortion in the plane of the panels. The method is applicable to all types of wood-based structural panels. The grain direction or orientation of the individual plies, laminations, or layers shall be parallel or perpendicular to the edge of the test specimen. If the plies, laminations, or layers are of different material or elastic properties, the method gives the effective shearing modulus. Wood-based structural panels in use include plywood, oriented strand board, and composites of veneer and of wood-based layers.

Note 1: This test method is primarily designed for material in which the grain or orientation of the individual plies, laminations, or layers is parallel or perpendicular to the edge of the specimen. It may be used, however, for plywood specimens in which the grain is at 45° to the specimen edges if a four-ply panel with all plies of the same thickness is used. The controlling condition is that the EI (modulus of elasticity × moment of inertia) values along both diagonals shall be equal.

1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.