The interlaminar shear strength (ILSS), the stress st which Mode II delamination occurs, can be measured using a Double Notch Shear test (DNS) This type of test should be performed according to standard proposal ASTM D 3846-79 [10].
Figure 5.12: Configuration of short beam shear test sample shows the geometry of a typical DNS specimen. Two notches are machined into the sample, one on either side, up to the same laminate layer. The sample is then axially compressed in a servo-hydraulic testing machine inducing shear loading on the bond area in between the two notches. Measurements of applied load and displacement are recorded.
Figure 5.13: Typical Output from DNS Test: Interlaminar Shear Strength shows the typical output from a DNS experiment. The stress is calculated as the maximum load divided by the cross section between the two notches of the specimen. The interlaminar shear strength corresponds to the maximum stress at failure.