  High-strain-rate shear tests were conducted on a three-layered bonded test
piece comprising a central aluminum layer with PMMA resin layers bonded on both
sides. Upon calculating the displacement field and the strain field using
digital image correlation (DIC), the crack tip was located, and the fracture
toughness was evaluated at the Aluminum/PMMA bonding interface. As a result of
the DIC, it was possible to determine the process by which 1) the elastic
stress wave propagated to the aluminum section, 2) the wave was transmitted to
the PMMA section, and 3) the crack developed at the interface. The tip of the
crack was identified using displacement distributions obtained using DIC. The
fracture toughness of the interface was evaluated using the stress intensity
factor. The true interfacial stress was calculated by correcting the strain
value at the interface obtained using DIC. The distribution of the stress
suggested that mode II fracture appears in the present test method when the
crack is sufficiently shorter than the length of the bonding interface, and
mode I and mode II fractures appear when the crack is longer in comparison.
Although the value of the stress intensity factor was disturbed by the error of
the DIC analysis, it was confirmed that the obtained values were similar
regardless of the difference in the crack length, upon averaging the stress
intensity factor values from the crack tips to the long-range with a ratio of 1
to the subset in DIC. As the obtained stress intensity factor value was similar
to the values calculated in the related literature, it can be concluded that
the method proposed in this study yields a reasonable stress intensity factor.
