Laboratory scale tests for the assessment of solid explosive blast effects

Abstract

The definition of blast loads applying to a complex geometry structure is, nowadays, still a hard task when numerical simulation is 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 one to model the charge itself, the structure and the surrounding air, which rapidly leads to large size models on which parametrical studies become unaffordable. So, on the basis of the Crank-Hopkinsons 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 nondestructive studies. In the context of security, the general aim is to study the effects of detonation shock waves in the vicinity of test installations and to test various shock wave mitigation means that could be implemented for the protection of facilities in sensitive locations. In particular, the set-up offers the possibility of measuring the loading in terms of pressuretime 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 test campaign that was conducted in the year 2006. 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 nondimensional characteristics of the pressure time history. The results obtained have been found to be in good agreement with reference curves available from the open literature. .