4.4.2 Tensile Stress

Tensile stress occurs when force is applied in a direction to elongate a material. Testing for adhesive tensile strength may be performed on cured homogenous specimens of the adhesive itself. These tests produce tensile property data that may include tensile strength in units of load per cross-sectional area, elongation in percent of the original length, tensile modulus (stiffness) and yield point. Tensile modulus is measured as the slope of the stress-strain plot in the Hookean or linear initial portion of the test; the units are the load per sectional area. Tests for bonded assemblies, such as the butt-joint test, apply force perpendicular to the plane of the bonded surfaces to pull them apart. These results are reported as loads per cross-sectional area and failure mode (see Section 7 for further discussion on failures).