Fracture Behavior Accompanying Electromagnetic Waves of Granite in Dynamic Three Point Bending

Abstract

A series of three-point bending tests for granite consisting of quartz, plagioclase, alkali feldspar and biotite was carried out at quasi-static and dynamic rates to examine the relation between its mechanical properties and electromagnetic phenomena during fracture. The output of ferrite-core antenna, which was located close to the specimen in a shielding box made of Permalloy plates, was measured through a band-pass filter. The dynamic bending strength was larger than the static one, i.e. the positive strain-rate dependence was observed in the strength of granite. It was also found that the intensity of electromagnetic waves measured in dynamic tests was much greater than that observed in static tests. This means that the electromagnetic phenomenon strongly depends on the loading rate, too.