Mode Ι fracture toughness of adhesively bonded composite joints under high loading rate conditions

The purpose of this paper is to investigate the mode I fracture behavior of adhesively bonded composite joints under high loading rate conditions. A dual electromagnetic split Hopkinson pressure bar system was established to apply symmetric dynamic loading on the double cantilever beam (DCB) specimens at 15 m/s and 30 m/s. The dynamic fracture toughness was then evaluated using an experimental-numerical approach and compared to the results of quasi-static loading rate (2 × 10⁻⁵ m/s and 2 × 10⁻⁴ m/s). Results indicate that high loading rate has obvious effects on the fracture toughness of composite joints. When the loading rate increases to 30 m/s, the mode I fracture toughness can reach a value of 1645 J/m², which is 119% higher than that of quasi-static conditions. At last, fracture surface inspections using scanning electron microscopy (SEM) were conducted to reveal such an effect.