Chapter 36 Shadowgraph Optical Technique for Measuring the Shock Hugoniot from Standard Electric Detonators Vilem Petr, Erika Nieczkoski, and Eduardo Lozano Abstract This research paper overviews the detonation characteristics of the liquid-desensitized function detonator used for the oil and gas industry. The liquid-desensitized function is designed to protect perforating tools from any liquid that penetrates inside the tool during operation. Additionally, the number 8 standard electric detonator is analyzed using the same technique. The measurement of the energy release from these types of initiation systems becomes critical for the evaluation of their initiation ability of the firing sequence, as well as from the standardization point of view. The Advanced Explosive Research Processing Group (AXPRO) presents a new method for experimentally measuring air shock properties and energy fluence from detonators by the using a single indoor experiment. The retro-reflective shadowgraph technique was used for measuring shock wave expansion rate. The method was effectively improved by replacing the continuous light with a strobe light. This new technique allows us to obtain much higher image quality than the one obtained by the Schlieren method. The shock Hugoniot and conservation equations provided a full characterization of the released energy from the high explosive base charge contained within the detonator. This technique produces data in general agreement with published data for the detonation and air shock properties from high explosives. This new method could constitute a practical and simplified experimental tool for industry use due to its relatively low cost, high data accuracy, and reduced data-analysis time. Keywords High-speed imaging • Retro-reflective • shock wave • Detonation • Initiation system 36.1 Introduction In order to initiate high explosives and the blasting agents, strong shock or detonation is required. A capsule of sensitive explosive material termed a detonator can accomplish this. Figure 36.1 shows two different designs of electric detonators that are generally used throughout the world. One is a standard mining and construction detonator Electric SP Number 8 and the other is a fluid desensitized oil and gas detonator Number 6. High-speed imaging technologies are constantly being improved for the study of detonation properties of explosive materials [1–9]. The goal of this research was to develop a “relatively simple” experimental method that validates the explosive energy inside of a detonator. The challenge of this endeavor emerges from the nature of manufacturing; detonator designs are always unique and the composition, as well as the combination, of explosive materials used is variable and depends on the manufacturer. The first detonator was developed in 1890s, and had a single explosive base. Since then, there have been significant improvements in initiation system technology. Presently, detonators frequently have two different explosive base materials: a sensitive primary explosive (primer charge), and a less sensitive, but more high-powered (brisance) secondary explosive (base charge), as is shown in Fig. 36.1. Detonator technology has developed significantly since the first initiation system was created. In general, a detonator consists of a metal capsule, tube or shell. The first detonator shells were constructed from paper, and then later advanced to copper, bronze, aluminum, and finally, plastic in the pursuit of the mitigation of fragments. There have also been advancements to universal detonator requirements. The United Nations’ specifications for electric detonators generally require a 7.00–8.00 mm diameter and a varying length depending upon whether the detonator is an instantaneous or delay type. V. Petr (*) • E. Nieczkoski • E. Lozano Colorado School of Mines, 1600 Illinois Street, Golden, CO 80401, USA e-mail: vpetr@mines.edu #The Society for Experimental Mechanics, Inc. 2017 S. Yoshida et al. (eds.), Advancement of Optical Methods in Experimental Mechanics, Volume 3, Conference Proceedings of the Society for Experimental Mechanics Series, DOI 10.1007/978-3-319-41600-7_36 279
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