THE EFFECT OF CONFINEMENT AND STAND-OFF DISTANCE IN BLAST TESTS

In recent years the explosive loads have received considerable attention due to different events, accidental or intentional, that have occured over important structures all over the world. In consequence, in the last decade there was an important activity in the research of explosive loads. Initially, this works were mostly empirical, but, in the last years, important researches have begun to be developed. Much of this work has concentrated on the response of monolithic metal beams and plates to impulsive loads. In particular, a set of experimental tests about clamped circular mild steel plates, of radius 53 mm, subjected to blast loads travelling along tubular structures was carried out at the Blast Impact and Survivability Research Unit (BISRU, University of Cape Town). Some counter-intuitive results about incident impulse and plate response were observed in the experiments. The main objective of this paper is to study numerically the wave propagation in the tube used for the tests and to compare the response with that obtained experimentally. The effects of confinement, stand-off distance and charge mass on the reflected pressures and impulses are studied. The stand-off distance is varied from 25 to 300 mm, and the load masses are varied from 4 to 15 g. Finally, the effect of the reflection on the plate is also analyzed. The analysis shows satisfactory correlation with experimental results.