Application and Analysis of Discrete Fiber Probes in Determining Detonation Velocity of Microcharges

This paper describes a method based on discrete fiber probes for measuring detonation velocity produced by microcharges. This method is simple to implement, scalable for multi-channel and requires minimal perturbation to the detonation wave. A simple experimental apparatus was established by using the oscilloscope, photodetectors, optical fibers, alignment device and initiation system. Four groups of experiments were carried out for analyzing the influence of probe spacing on detonation velocity. The experiment results suggest that a relatively appropriate distance between two adjacent fiber probes is 4 mm. In addition, the comparative experiments between ionization probes and fiber probes were performed, which shows that the standard deviation of detonation velocity obtained by fiber probes is smaller under the same measurement conditions. This research may be useful for the development of determining detonation velocity precisely of microcharges.

Experimental Evaluation of Combined Effect of Flexure, Shear and Tension on SFRC Beams

Short discrete fiber reinforcement is the right choice in the concrete matrix. De-bounding and pulling out of fibers requires more force, thereby increasing the durability and confrontation to repeat and dynamics loads. Fibers substantially decrease the fragility of concrete and advance its engineering characteristics, like load bearing capacity, resistance against impact load, flexural, tensile and fatigue etc. Behavior of SFRC in tension, compression, flexure and shear has already been studied separately but no or very little work has been done on combined state flexure, tension, shear, torsion etc. Present study involves the investigation of the behavior of SFRC composite M20 beams with varying percentage fiber content (0.0, 0.50, 0.75 & 1.0%) by volume under the combined state of tension and shear and flexure. The testing beam size was taken as100 mm × 100 mm × 500 mm. Straight fibers 28 mm long and 0.28 mm diameter were castoff. The specimen beams were tested applying direct tension of 0, 5, 7 and 10kN. For different fiber percent by weight beams were tested, all the direct tension values were applied to each of the three beams i.e. total of 48 beams were casted and tested accordingly. For the beam under combined effect of tension, flexure and shear, when tested it was observed that ultimate central deflection and ultimate bending stress were found to decrease for a particular percentage increment of fiber added along with increase of tension. It was also observed that for a specific tension value, deflection increases with increase of fiber percentage at ultimate load in beams. Bending stress increases at tension 10 KN for all percentages of fiber content.