Page 187 - Handbook of Adhesives and Sealants

Standard Test Methods 157

Figure 4.13 Comparison of peel force with adhesive thickness (0.5 mil
polyester film used as backing in all tests). 8
4.4.5 Fatigue tests
Fatigue testing places a given load repeatedly on a bonded joint.
Lap-shear or other specimens are tested on a fatiguing machine ca-
pable of inducing cyclic loading (usually in tension or a combination
of tension and compression but also in bending) on the joint. ASTM D
3166 provides procedures for testing and measurement of the fatigue
strength of lap specimens.
The fatigue strength of an adhesive is reported as the number of
cycles of a known load necessary to cause failure. Cycles to failure and
the corresponding loads are plotted on coordinates of stress versus the
logarithm of the number of cycles. The point at which the smooth
curve connecting the points of minimum stress crosses the 10 million