Page 178 - Handbook of Adhesives and Sealants

148 Chapter Four

ton specimen. This design is commonly used to measure the tensile
strength of adhesives between dissimilar materials. This method is
also useful if the adherend cannot be machined into the shape of the
button specimen. With some modifications in the dimensions, the
button tensile test has also been adapted for testing adherence of
honeycomb-cover sheets to the core (ASTM C 297).
Although developed and used primarily for testing wood joints, the
cross type tension test, shown in Fig. 4.3, can be used to test other
substrates or honeycomb specimens (Fig. 4.3c). This simple cross lap
specimen is described in ASTM D 1344. This test method is attractive
in that it does not involve significant machining or high specimen cost,
as the button tensile test specimens do. It is very important that the
specimens are thick and rigid enough to resist bending. With only
moderate bending, the loads will quickly go into peel or cleavage
stress. Because of a high degree of variation arising out of possible
bending modes, a sample population of at least ten is recommended
for this test method.

Figure 4.3 Cross-lap tension test
specimen. 4