Design and Calibration of PVDF Based Stress Gauge and Its Application in Concrete Cylinder Impact Test

In this paper, a kind of stress gauge under high strain rate which employs polyvinylidene fluoride (PVDF) film as sensitive component was developed. The dynamic piezo constant of the developed PVDF based stress gauge was calibrated on the split Hopkinson pressure bar (SHPB) with a certain measurement circuit. By comparison the signals measured from the PVDF based stress gauge with that from strain gauges installed in the SHPB, the calibration value of 27.21PC/N for the developed PVDF based stress gauge was determined. A series of axial impact testing on concrete cylinder specimens with embedded PVDF based stress gauges were conducted by a unique drop-hammer test facility. The stress history of concrete was successfully measured by the newly developed PVDF based stress gauge. Results show that the stress value measured by the PVDF based stress gauge is more accurate than those calculated by the strain measured from the hammer. By the signal analysis of axial compressive displacement and the stress measurements, the dynamic stress-strain curve of the concrete cylinder specimens was derived. The experimental results indicate that the PVDF based stress gauge can provide a novel way for stress measurement of concrete specimens under impact and has the potential to be applied in impact test and health monitoring of concrete structures.