ASTM D3983-98(2004)

This test method is capable of providing shear modulus and shear strength values for adhesives with accuracy suitable for use by design engineers in predicting the characteristics of building assemblies bonded with nonrigid adhesives. Adhesive formulators will also find the method useful during the development of new adhesive systems. In general, the thick adherend lap-shear test is a useful tool in research during studies of both short- and long-term load-deformation properties of adhesives. This thick adherend lap-shear test yields a uniformity of stress distribution approaching that obtained in thin tubular butt joints subjected to torsion, which is considered to be a condition of pure shear.

The user is cautioned that pure shear strength cannot be obtained by this test method, because some tensile and compression stresses and stress concentrations are present in the joint. The estimate of shear strength by this test method will be conservative. If pure shear strength is demanded, then Test Method E 229 should be used.

1.1 This test method describes a method of measuring the shear modulus and rupture stress in shear of adhesives in bonded joints. The method employs lap-shear specimens with wood, metal, or composite adherends, with adhesives having shear moduli ranging up to 700 MPa (100 000 psi). This test method is suitable generally for joints in which the ratio of adherend tensile modulus to adhesive shear modulus is greater than 300 to 1. It is not suitable for adhesives that have a high shear modulus in the cured state and that also require elimination of volatile constituents during cure.

1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.

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 and health practices and determine the applicability of regulatory limitations prior to use.