Air-blast Effects on Structural Shapes

A study was performed to investigate the effect of a W-shape section with finite dimensions on the loading parameters. Two main mechanisms were hypothesized for reducing the loading; 'clearing' and 'wrap-around'. Firstly, the ability of the blast wave to clear around the section potentially could lead to the pressure decaying faster than that of an infinite surface, a process known as 'clearing'. The other mechanism of wraparound occurs when the pressure wave engulfs the section, causing the load on the rear face of the flanges to oppose the load on the front faces, which lowers the impulse imparted to the section. Using the hydrocode Air3d, design of experiment procedures and linear regression techniques, a series of analyses were performed. The results of the study, suggest that peak pressures remain unchanged regardless of the 'finiteness' of the section and impulse appears to be substantially influenced by both 'clearing' and 'wraparound'.