Page 180 - Handbook of Adhesives and Sealants

150 Chapter Four

Figure 4.4 Standard lap shear test specimen design:
(a) form and dimensions of lap shear specimen; (b)
standard test panel of five lap shear specimens. From
ASTM D 1002

(ASTM D 3165) shown in Fig. 4.5a and the double lap specimen
(ASTM D 3528) shown in Fig. 4.5b. These specimens minimize joint
eccentricity and provide higher strength values than does the single
overlap specimen. For the specimen in Fig. 4.5a, the overlap joint can
be made from saw cuts in the top and bottom substrates of a bonded
laminate. This process negates the effects of extruded adhesive at the
edges of the lap and the sheared edge of the standard type of lap shear
specimen. As a result, the chances of deformation and uneven surface
preparation are lessened.
Compression shear tests are also commonly used. ASTM D 2182
describes a simple compression specimen geometry and the compres-