A STUDY ON THE RESPONSE OF SINGLE AND DOUBLE CIRCULAR PLATES SUBJECTED TO LOCALISED BLAST LOADING

Abstract

THE RESPONSE OF SINGLE AND DOUBLE LAYERED STEEL PLATES TO LOCALISED AIR-BLAST LOADING WAS EXAMINED. TWO CONFIGURATIONS, BOTH COMPRISING FULLY CLAMPED CIRCULAR PLATES WITH A 200 MM EXPOSED DIAMETER, WERE CONSIDERED: 4MM THICK SINGLE AND (2+2) MM DOUBLE LAYERED PLATES. THE LOCALISED AIR-BLAST LOADING WAS APPLIED BY CENTRALLY DETONATING DISCS OF PE4 PLASTIC EXPLOSIVE. SIMILAR FAILURE MODES WERE EVIDENT IN THE SINGLE AND DOUBLE PLATE CONFIGURATIONS, NAMELY, MODE I (LARGE INELASTIC DEFORMATION) AND MODE II (CAPPING FAILURE ALONG WITH DEFORMATION) RESPONSES. THE DOUBLE PLATES EXHIBITED LARGER MIDPOINT DEFLECTIONS THAN THE SINGLE PLATES, AND PARTIAL TEARING OF THE FRONT PLATE IN THE DOUBLE PLATES WAS OBSERVED AT A LOWER IMPULSE THAN IN THE SINGLE PLATES. HOWEVER, COMPLETE CAPPING OF BOTH PLATES IN THE DOUBLE PLATE CONFIGURATION OCCURRED AT THE SAME CHARGE MASS AS FOR THE SINGLE PLATES, IMPLYING THAT BOTH CONFIGURATIONS OFFER EQUIVALENT PROTECTION FROM CAPPING FAILURE AS A RESULT OF THIS TYPE OF LOCALISED BLAST LOADING. A METALLOGRAPHIC STUDY OF THE DEFORMED AND TORN PLATE REGIONS DID NOT REVEAL ANY PHASE TRANSFORMATION IN THE STEEL. IT WAS ALSO FOUND THAT THE 2 MM THICK PLATES EXHIBITED LARGER INCREASES IN GRAIN SIZE THAN THE 4 MM THICK PLATES.