Shear Strength and Torsion Tests

Shear strength is defined as the maximum stress that a material can withstand before failure in shear. In a planar shear test, opposing forces are applied parallel to the cross-sectional area under test.

Torsion tests also provide an indication of shear properties. Torsion test evaluate materials or products under twisting loads or opposing radial forces according to ASTM E-143 or ISO equivalent standards. Data from torsion test is used to construct a stress-strain diagram and to determine elastic limit torsional modulus of elasticity, modulus of rupture in torsion, and torsional strength.

Calculation of shear strength depends upon the test method. For instance, the shear strength of a plastic is the maximum load required to shear a specimen in such a manner that the resulting pieces are completely clear of each other. Plastic shear strength is reported in psi based on the area of the sheared edge (ASTM D-732). Timber shear strength is determined by methods given in ASTM D-143 and ASTM D-198. ASTM E-299 defines the shear strength of a structural adhesive has the maximum shear stress in the adhesive prior to failure under torsional loading.