School of Mechanical, Industrial, and Aeronautical Engineering, University of the Witwatersrand, PO WITS, 2050 Johannesburg, South Africa
Skews, B.W., School of Mechanical, Industrial, and Aeronautical Engineering, University of the Witwatersrand, PO WITS, 2050 Johannesburg, South Africa; Bugarin, S., School of Mechanical, Industrial, and Aeronautical Engineering, University of the Witwatersrand, PO WITS, 2050 Johannesburg, South Africa; Sawicka, E., School of Mechanical, Industrial, and Aeronautical Engineering, University of the Witwatersrand, PO WITS, 2050 Johannesburg, South Africa
Previous studies of the impact of a blast or shock wave on a layer of textile positioned a short distance in front of a surface have shown that significant pressure amplification can occur. These studies have all dealt with the case of head-on impact on plane textile surfaces. This study extends such work to plane textile specimens inclined to the wave propagation direction, both for the textile freely suspended in order to examine the transmitted wave and with it positioned a short distance in front of a solid surface. Tests are also conducted with the textile suspended in a cylindrical shape positioned in front of a curved surface to approximate a more realistic practical loading case on a torso. Three textile types were used, varying significantly in permeability. In the oblique impact case it is found that the pressure amplification decreases as the wall angle decreases. The behaviour of the wave system in the gap between the textile layer and the body is clarified, showing a succession of oblique shock reflections and transmissions back through the textile layer. Tests on the cylindrical body surface at low Mach number show no significant amplification at the most forward position and steadily decreasing pressure around the sides of the surface. The concern regarding very large increases in pressure which arose from tests on head-on impact on plane surfaces appear to be ameliorated when the body is curved. Computer simulations are used to confirm the wave pattern for the cylindrical case by modeling a curved porous surface a short distance in front of a rigid wall. © 2009 Elsevier Ltd. All rights reserved.
Blast loading; Curved surfaces; Cylindrical bodies; Cylindrical shapes; Low Mach numbers; Oblique impact; Plane surfaces; Porous surface; Rigid wall; Shock reflection; Short distances; Solid surface; Surface pressures; Textile surfaces; Transmitted waves; Wave patterns; Wave propagation direction; Wave system; Clarification; Computer simulation; Mach number; Offshore structures; Pressure effects; Shock waves; Textiles; Amplification
