Dynamic fracture energy of polyurea-bonded steel/E-glass composite joints

We report dynamic fracture energy measurements for E-glass/polyurea/steel joints at a peak strain rate of 1.2 × 107 s−1. Experiments were done by initiating a crack at the steel/polyurea interface by a laser-generated stress wave, whose profile was recorded using optical interferometry. The critical energy release rate or the energy delivered by the propagating stress wave to the crack-tip region at crack initiation was computed by using a wave dynamics simulation. An average value of 359 (±19) J/m2 was obtained. The effect of moisture on the fracture energy values was also examined. Results showed that the values reduced by only 3% to 349 ± 19 J/m2 in samples that were exposed to 75% RH at 65 °C for 30 days. In addition to using the data as a local failure criterion in large-scale simulation of structural joints, it can be used to estimate the residual fracture energy of the E-glass/polyurea/steel joints in service.

► The fracture energy of polyurea-bonded steel/E-glass composite joints was measured to be 359 (±19) J/m2. ► The effect of moisture on the fracture energy was minimal such that it reduced by only 3%. ► Established a design criterion for structural joints.