Laboratory scale tests for the assessment of solid explosive blast effects. Part I: Free-field test campaign

Abstract

The definition of blast loads applying on a complex geometry structure is still nowadays a hard task when numerical simulations are used, essentially because of the different scales involved: as a matter of fact, modelling the detonation of a charge and its resulting load on a structure requires to model the charge itself, the structure and air surrounding, which rapidly leads to large size models on which parametrical studies become unaffordable. So, on the basis of the Crank–Hopkinson’s law, an experimental set-up has been developed to support reduced scale structures as well as reduced scale detonating solid charges. As a final objective, the set-up must be used to produce the entry data for numerical assessments of the structure resistance. This set-up is composed of a modular table, sensors and targets and has been designed to conduct non-destructive studies. In the context of security, the general aim is to study the effects of detonation shock waves in the vicinity of facility buildings and to test various shock wave mitigation means that could be implemented for the protection of facilities in sensitive locations. Especially, the set-up offers the possibility to measure the loading in terms of pressure-time curves, even for very complex situations like multiple reflections, combination and diffraction. The present paper summarizes the development of the set-up as well as the first tests performed. The main features of the table, the instrumentation and the pyrotechnics are given. Also the paper summarizes a first qualification tests campaign that has been conducted. In this campaign, free-field blast tests (i.e. blast tests performed without structures) have been conducted. Overpressure maxima, arrival time of the shock wave and impulse are presented as non-dimensional characteristics of the pressure-time history. The results obtained have been found in good agreement with reference curves available from the open literature and numerical model results.