Block-Shear Strength Test
Standard Test Method for Shear Strength of Adhesive Bonds Between Rigid Substrates by the Block-Shear Method
ASTM D4501 specifies a standard test method for the characterization of block-shear strength for adhesives. This test is used when the moduli of the bonded materials is stronger than the modulus of the adhesive i.e. hard, rigid materials. Different types of materials may be bonded together including ceramic, glass, metal, plastic, or wood.
Thin square blocks of material are bonded together by the adhesive that is to be tested. The exact size measurements of the test samples depends on the type of material being used.
The block-shear fixture is designed to accomodate specimens in sizes from 30x30x13mm (HxWxT) to 80x80x13mm. Typically, a 1 inch square shearing block is adhered to the center of a larger square holding block.
The ASTM D4501 fixture is used in conjunction with two tensile testing wedge grips. There is a small sample clamp in the back which secures the holding block during the test. Once the test is begun, the wedge grips will pull the shearing guillotine until the shearing block has been sheared away from the holding block.
The maximum shear stress is given by the peak load reported in lbf/in. (psi) or in megapascals (MPa). The amount of adhesive used during the test should be reported as well based on its thickness.