Use of the shockwave generator for research on low-level blast effects - Monitoring vs. measurement tools

  • In order to contribute to the research efforts on primary explosion effects, an experimental setup was created to generate realistic overpressure load cases under the most reproducible conditions and with short setup times. One focus of the project is now the applicability of this test setup for Low Level Blast (LLB) testing [1-3]. The basis of our experimental setup is the Shockwave Generator (SWG), which has already been presented in detail [4]. In addition, a stand-alone measurement system has been developed that can be worn by the operators who are exposed to LLB. The measuring system is referred to as the ´Sensor Carrier for Operator´ (StEk; German abbr.: Sensortraeger Einsatzkraft). With the StEk, it is possible to record LLB exposures in training scenarios with a measuring accuracy satisfying scientific requirements and thus to classify the corresponding LLB load case of the respective weapon system or training scenario. In the test series presented here, the StEk was attachedIn order to contribute to the research efforts on primary explosion effects, an experimental setup was created to generate realistic overpressure load cases under the most reproducible conditions and with short setup times. One focus of the project is now the applicability of this test setup for Low Level Blast (LLB) testing [1-3]. The basis of our experimental setup is the Shockwave Generator (SWG), which has already been presented in detail [4]. In addition, a stand-alone measurement system has been developed that can be worn by the operators who are exposed to LLB. The measuring system is referred to as the ´Sensor Carrier for Operator´ (StEk; German abbr.: Sensortraeger Einsatzkraft). With the StEk, it is possible to record LLB exposures in training scenarios with a measuring accuracy satisfying scientific requirements and thus to classify the corresponding LLB load case of the respective weapon system or training scenario. In the test series presented here, the StEk was attached to an operator dummy and exposed to an overpressure load case. The results of the StEk were compared with a pencil probe (PP), which was positioned symmetrically to the StEk in the undisturbed blast propagation area of the SWG. The aim of the test series was to compare the accuracy of the self-sufficient measurement setup StEk with the conventional pressure measurement method (PP). Conventional, market-available blast exposure monitoring device (BEMD) (type: B3 Blast Gauges Gen.6) were used in parallel to check their accuracy. Setup & Method The experimental setup is shown in Figure 1 (left). The StEk system was attached to a dummy placed at a 45° angle to the SWG pressure outlet at a distance of 1 m. A PP was placed axially mirrored. The sensors of the StEk were placed in the typical positions for BEMD. With reference to the incident shockwave, one sensor was placed on the chest (face-on) and one on the shoulder (side-on). The BEMDs were also placed in the same positions. The standalone StEk measurement system is described in the following. The complete measuring chain was realized as one stand-alone, self-sufficient unit. The system is based on a 20-liter backpack system, which contains the power supply, the measuring amplifier and the data acquisition system (DAQ) (Figure 1 (right)). The amplifier has four channels, an integrated 50 kHz low pass filter and is suitable for use with integrated charge piezoelectric (ICP) pressure sensors. A sampling rate of up to 2 MHz can be used Data is stored in a buffer of 64 MS. The computer, a Tablet PC, is attached to the front of the backpack to allow quick access. The pressure sensors are connected to the BNC interfaces on the outside of the housing using coiled BNC cables. The coiled BNC cables allow maximum freedom of movement and reduce mechanical stress on the couplings. In the current configuration, up to four ICP pressure sensors can be mounted on the operator (type: PCB132B38). The pressure sensors are flush-mounted in a 30 mm × 30 mm carrier plate. Results & Discussion Figure 2 (a) shows the overpressure generated by the SWG measured with the PP. The idealized pressure curve can be seen. The second peak is a reflection that occurs within the SWG. Figure 2 (b) shows the pressure measured by the BEMDs. It can be seen that both pressure curves correspond approximately to the idealized pressure curve. This is remarkable because the chest sensor was facing forward and should have a dynamic pressure component caused by the movement of the gas [5]. However, the pressure curves in Figure 2 (b) show the idealized pressure curve that should occur with a side-on overpressure measurement in the undisturbed free field. Therefore, it can be assumed that software modeling is used to generate an idealized pressure curve from the blended pressure curve that is intended to represent the overpressure that will occur. Figure 2 (c) shows the pressure curves of the ICP pressure sensors of the StEk system. It can be seen that the characteristics of the pressure curves were affected by the dynamic pressure component. The shoulder sensor, which, due to the nature of the dummy posture and position, was not exposed perfectly side-on, also showed a dynamic component. Calculations based on the peak overpressures of the PP confirm, that the reflected pressure was visible on the face-on chest sensor [5]. A limiting factor is that the sensor mounts and the dummy itself are subject to mechanical excitation, which probably explains the interference frequency seen in the pressure signal. The test results show the limitations of BEMDs for scientific investigations of weapon systems, as it is assumed that a high degree of modeling of the pressure curves takes place during post-processing. However, as the comparison of the BEMDs with the PP pressure curves shows, the pressure curve fit matches the PP pressure curve sufficiently well. This shows that a scientific measurement system such as StEk should be used initially to investigate and assess the load case from weapon systems or training scenarios in order to capture the real and complete characteristics of the load case.zeige mehrzeige weniger

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Autor*innen:Henrik Seeber
Koautor*innen:Daniel Krentel, Marco Gerbeit, Dennis Grasse, Steffen Grobert, Marcel Donner
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2025
Organisationseinheit der BAM:2 Prozess- und Anlagensicherheit
2 Prozess- und Anlagensicherheit / 2.1 Sicherheit von Energieträgern
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten
Freie Schlagwörter:Blast injury; Low Level Blast; Primäre Explosionswirkung; Shock wave generator
Themenfelder/Aktivitätsfelder der BAM:Infrastruktur
Infrastruktur / Security
Veranstaltung:8th International Forum on Blast Injury Countermeasures
Veranstaltungsort:Tokio, Japan
Beginndatum der Veranstaltung:07.05.2025
Enddatum der Veranstaltung:10.05.2025
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:11.06.2025
Referierte Publikation:Nein
Eingeladener Vortrag (wissenschaftliche Konferenzen):Nein
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