Combined blast and fragment loading on plates

Abstract

This thesis was written at SIMLab at NTNU during 20 weeks of the spring semester of 2011.

An increasing need for lightweight protective structures for both military and industrial applications has made the traditional use of concrete structures impractical, and has triggered increased research and development of steeland aluminium protective structures.

The aim for this thesis is to investigate the synergetic effect of combined blast and fragment loading on thin steel plates. Experiments were performed using a pressure tank to simulate blast loading on plates with premade holes.The experiments were meant to imitate the effect of a blast wave hitting a thin steel plate penetrated by fragments travelling in front of the pressure wave. Largely the experiments were successful, though some results turned outto be deviant. Apart from decreasing the overall strength of the plates, the holes had no notable adverse effects.

In order to investigate the problem further, numerical analyses were performed. A high number of simple analyses were run to establish a foundation upon which more complex analyses could be based. A reasonable level of similarity to the experiments was observed.

Analyses were also run applying both uncoupled and coupled Eulerian and Lagrangian analyses. These analyses recreated recorded pressure levels from the experiments quite well, but resulted in exaggerated responses due tohigher loading rate.