IngentaConnect On size and boundary effects in scaled model blasts spatial probl...

Authors: Rossmanith, H.¹; Uenishi, K.²

Source: Fragblast, Volume 9, Number 3, September 2005 , pp. 139-174(36)

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Abstract:

This paper addresses size and boundary effects on wave propagation, fracture pattern development and fragmentation in small scale laboratory-size specimens for model blasting. Small block type specimens are centre-line loaded by linear explosive charges and supersonically detonated. Using elastic wave propagation theory and fracture mechanics it is shown that the type of boundary conditions which prevail at the outer boundary of the cylinder control the extension of bore-hole cracking and fragmentation within the body of the cylinder. In the case of a composite block where a cylindrical core of different material is embedded, the level of fracturing and fragmentation is controlled by the separation of the interface which in turn depends on the relative dimensions of the core and the block. The most important parameter is the ratio between the length of the pulse (space-wise or time-wise) and the characteristic dimensions of the models, i.e. in this case the dimensions of the core and the mantel. Stress wave superposition effects occur in the corner sections of the mantel. Theoretical results are in good agreement with recent experimental findings.

Keywords: Scaled model blasts; Supersonic detonation; Fracture network; Wave propagation

Document Type: Research article

DOI: 10.1080/13855140500298339

Affiliations: 1: Institute of Mechanics, Vienna University of Technology, Vienna, Austria 2: Research Centre for Urban Safety and Security, Kobe University, Kobe, Japan

On size and boundary effects in scaled model blasts spatial problems