Magnetic gauge for free surface velocities in reinforced concrete blasted by explosives

18th APS-SCCM; 24th AIRAPT

Ashuach, Y.^1 ; Gissis, I.^1 ; Avinadav, C.^1

Rafael Advanced Defense Systems, Ltd., PO Box 2250, Haifa

3102102, Israel^1

关键词: Blast experiments;    Computational codes;    Concrete surface;    Doppler interferometers;    Free surface velocity;    Measured currents;    Measurement techniques;    Point of interest;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/500/14/142002/pdf
DOI  :  10.1088/1742-6596/500/14/142002

来源: IOP

【 摘 要 】

We developed a simple magnetic gauge for measuring free surface velocities of rock materials in the range of 0.1-20 m/s. The gauge consists of two elements: a NdFeB magnet and a pick-up coil. The coil is attached to the free surface at the point of interest. The magnet is placed a few centimeters away from the coil and the rock. The motion of the rock surface, due to blast loading, induces current in the coil due to the changes in the magnetic flux. The coil velocity is deduced from the measured current using a computational code. The gauge was tested and validated in a set of free-falling experiments. We present velocity measurements from various blast experiments in limestone and reinforced concrete, using both the magnetic gauge and a Doppler interferometer. The results obtained from the two measurement techniques are in good agreement. Since the magnetic gauge is cheap and very simple to operate, it is well-suited for mapping the velocity distribution at multiple points of interest on the concrete surface.