High-frequency fiber Bragg gating accelerometer and strain sensor-based blast test on a concrete slab.

The blast test is the most direct method of measuring explosive performance and structural safety. Because of long-distance wires and electromagnetic interference, some scattering exists in the blast test using electrical sensors. For this paper, a double-hinge high-frequency fiber Bragg gating (FBG) accelerometer was designed and manufactured to measure the acceleration on a blast-loaded concrete slab. The resonance frequency and sensitiveness of the sensor were determined as 3400 Hz and 6.26 pm/g, respectively. Blasting was performed seven times, with each blast generating the energy equivalent of 50 kg of TNT. The stress waves were obtained from the blast source for distances at 4 m, 6 m, and 8 m. The peak accelerations in test 6 were obtained as 396.21 g, 123.57 g, and 38.88 g, respectively, whereas the propagation velocity of the stress wave was around 2500 m/s. Furthermore, the study was complemented by numerical simulations. The test results were compared with the empirical formula, which validated the reliability and applicability of fiber optical sensors in blast testing. The proposed fiber optical sensors have shown promising results, further boosting their practical applications in blast testing and monitoring structural health following a blast shock.