Shear Modulus
Shear modulus, also called modulus of rigidity, indicates
the resistance to deflection of a member caused by shear
stresses. Shear stress is different from tension or compression stress in that it tends to make one side of a member slip
past the other side of a member adjacent to it. There are two
main types of shear in different planes of wood-based panels: interlaminar shear and edgewise shear or shear throughthe-thickness. Interlaminar shear is also commonly called
planar shear (or rolling shear, or horizontal shear) in plywood panels to describe stress that acts between the veneers
that are glued with grain direction in adjacent pieces perpendicular to one another. For example, when the plywood
panel is loaded in the middle with its two ends simply supported, the layers or veneers tend to slip horizontally past
each other as the panel bends. The glue-bonding between
the laminates of veneers resists the slipping and often dictates the panel stiffness. Edgewise shear is also commonly
called racking shear. The moduli of rigidity vary within and
between species, resin application, moisture content, and
specific gravity. The procedure to determine different shear
moduli for fiber- and particle-based panels is described in
ASTM D 1037 and for structural panels in ASTM D 3044
Tags Plywood Shear Modulus test
