Long duration blast loading of cylindrical shell structures with variable fill level

Abstract

This paper investigates the effect of long-duration blast loads on the structural response of aluminium cylindrical shell structures containing varying fluid levels. A detailed non-linear numerical model comprising remapped Lagrangian analysis examines localised plate buckling and deformation. The relative computational accuracy of an uncoupled numerical model developed in this paper is compared with experimental results obtained at one of the worlds’ most powerful air blast testing facilities. Evaluating structural response for blast loads with an extended dynamic pressure phase is exceptionally difficult using only Eulerian controlled CFD methods; due to domain constraints incorporating restrictive cell sizes engulfing the target structure before remapping. The further complexity of shock transmission through a structure damped by an internal fluid is examined experimentally. Fibre optic controlled instrumentation and high speed photography provide a vital insight towards coupled flow-field behaviour of the shell structure. Surface mounted pressure gauges on the cylindrical wall accurately record the pressure time history throughout the passage of the shock wave. This paper highlights the key influence on blast response due to varying internal fluid levels and the relative importance pertaining to a conservative design solution for varying operational states. Numerical modelling in this paper demonstrates the robust accuracy achievable for a remapped Lagrangian solution. The routine analytical assumption of uniform drag forces acting on the structural body was shown to be both misleading and inaccurate by comparison. This research will be of direct interest to both practitioners and researchers considering high power explosive blasts from sources such as hydrocarbon vapour cloud ignition.

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Identifiers

ORCID for S.K. Clubley: orcid.org/0000-0003-3779-242X

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