TY - CONF A1 - Seeber, Henrik A1 - Grobert, Steffen A1 - Krentel, Daniel A1 - Kluge, Martin A1 - Hauer, Thorsten T1 - Investigation of intracorporeal shock wave propagation using a simplified torso model and a shock wave generator N2 - Blast injuries are among the most common injuries in military operations. Also, in civilian environments, more explosive threats are expected in the future due to emerging conflicts and threats. While the effect of fragments, which is classified as secondary blast injury, could be minimized by police and military personnel’s modern ballistic body protection systems, the effects of shock wave propagation in the body as part of the primary explosion trauma still remain a serious threat needing further research. The detonation-physical processes of highly dynamic pressure changes within the human body, the reflection-related amplification of shock waves at organ-dermis interfaces, and the consequences of injury mechanisms have become more prominent in international research. Various approaches have been used to investigate these aspects. Animal experiments on free field test sites or shock tube setups combined with a subsequent biological evaluation and numerical simulations provided promising results and allowed the discussion of different biomechanical aspects. However, due to poor reproducibility and a lack of short-term dynamic material properties, most research approaches have significant limitations. Laboratory test setups do not represent real-scale high explosive detonation parameters with regards to pressure characteristics, impulse duration and blockage problems. Measured values are interpreted with partly outdated, selective and not validated limit values for overpressures from field tests with animals. This is due to the lack of a validated and comprehensive data set covering a variation of the crucial parameter. Injury mechanisms and their effects have not yet been sufficiently elucidated for the torso and extremities. In order to contribute to the research efforts on the primary explosion effects, the German Federal Armed Forces established an interdisciplinary military medical research project in cooperation of the Bundeswehr Hospital Berlin and the German Federal Institute for Materials Research and Testing (BAM). The aim of the planned investigation is the development of a multidisciplinary method to investigate shock wave behavior in various generic tissue simulants under the most reproducible conditions possible with realistic loads in an experimental test series with short set-up times. T2 - 7th International Forum on Blast Injury Countermeasures CY - Tokio, Japan DA - 17.05.2023 KW - Shock wave generator KW - Blast injury KW - Primäre Explosionswirkung KW - Experimental setup PY - 2023 AN - OPUS4-60045 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Seeber, Henrik ED - Krentel, Daniel ED - Grasse, Dennis ED - Gerbeit, Marco ED - Grobert, Steffen ED - Hauer, Thorsten T1 - Experimental Setup for the Reproducible Generation of Pressure Waves in Free Field Conditions N2 - The injuries caused by the primary blast are still poorly understood, especially in the torso region. To generate sufficiently large data sets, shock tubes are often used. However, these have some limitations, such as blockage, use of the exit jet, widening cross-sections, and scaling problems with respect to compressive strength and test objects. Therefore, it is appropriate to conduct experiments under free-field conditions, but tests with real explosives are often associated with long preparation and setup times as well as high safety requirements. Therefore, this paper presents an experimental setup for the reproducible generation of blast waves under free-field conditions. This experimental setup aims to provide a test environment for a sufficiently large specimen to investigate the behaviour of the shock wave within the specimen, especially at the media interfaces. As an example of application, the influence of the primary explosive effect on protective equipment or on tissue simulants for the investigation of blast injuries can be mentioned. An autoclave is used as a shock wave generator. It has a volume of 0.065 m3 and is filled with a stoichiometric acetylene-oxygen gas mixture. The setup and turnaround time is approximately 30 minutes. The following factors have been selected as target variables for the optimization of the shock wave generator: reproducibility of the pressure wave, use-case-relevant positive phase duration and peak overpressure, a pressure curve characteristic corresponding to that of a military explosive under undisturbed free field conditions, and short setup times of the experimental setup. For this purpose, the experimental setup is presented in this paper. Several series of measurements are presented, showing the characteristics of the generated pressure wave. For the generated pressure wave, the classical pressure curve characteristics can be clearly recognized. A peak pressure of 92 kPa is reached at a distance of 1 m from the opening, and the first positive pressure phase lasts 1.17 ms. Furthermore, the pressure wave propagates in a hemispherical shape. The typical characteristics of the blast wave generated by the SWG have been demonstrated using the military explosive PETN. It is shown that the actual load case corresponds to about 70 g of PETN. T2 - 26th International Symposium on Military Aspects of Blast and Shock CY - Wolongong, Australia DA - 03.12.2023 KW - Shock wave generator KW - Blast injury KW - Pressure wave KW - Experimental setup PY - 2023 SP - 1 EP - 13 AN - OPUS4-59357 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Seeber, Henrik A1 - Grobert, Steffen A1 - Krentel, Daniel A1 - Gerbeit, Marco T1 - Experimental Setup for the Reproducible Generation of Pressure Waves in Free Field Conditions N2 - The injuries caused by the primary blast are still poorly understood, especially in the torso region. To generate sufficiently large data sets, shock tubes are often used. However, these have some limitations, such as blockage, use of the exit jet, widening cross-sections, and scaling problems with respect to compressive strength and test objects. Therefore, it is appropriate to conduct experiments under free-field conditions, but tests with real explosives are often associated with long preparation and setup times as well as high safety requirements. Therefore, this paper presents an experimental setup for the reproducible generation of blast waves under free-field conditions. This experimental setup aims to provide a test environment for a sufficiently large specimen to investigate the behaviour of the shock wave within the specimen, especially at the media interfaces. As an example of application, the influence of the primary explosive effect on protective equipment or on tissue simulants for the investigation of blast injuries can be mentioned. An autoclave is used as a shock wave generator. It has a volume of 0.065 m3 and is filled with a stoichiometric acetylene-oxygen gas mixture. The setup and turnaround time is approximately 30 minutes. The following factors have been selected as target variables for the optimization of the shock wave generator: reproducibility of the pressure wave, use-case-relevant positive phase duration and peak overpressure, a pressure curve characteristic corresponding to that of a military explosive under undisturbed free field conditions, and short setup times of the experimental setup. For this purpose, the experimental setup is presented in this paper. Several series of measurements are presented, showing the characteristics of the generated pressure wave. For the generated pressure wave, the classical pressure curve characteristics can be clearly recognized. A peak pressure of 92 kPa is reached at a distance of 1 m from the opening, and the first positive pressure phase lasts 1.17 ms. Furthermore, the pressure wave propagates in a hemispherical shape. The typical characteristics of the blast wave generated by the SWG have been demonstrated using the military explosive PETN. It is shown that the actual load case corresponds to about 70 g of PETN. T2 - 26th International Symposium on Military Aspects of Blast and Shock CY - Wollongong, Australia DA - 03.12.2023 KW - Shock wave generator KW - Blast injury KW - Pressure wave KW - Experimental setup PY - 2023 AN - OPUS4-59356 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Seeber, Henrik A1 - Grobert, Steffen A1 - Krentel, Daniel A1 - Hauer, Thorsten T1 - Influence of torso protective equipment on intracorporeal shock wave behavior N2 - In the field of explosive reactions, there is a type of explosive effect that lacks a sufficient database and reproducible experiments regarding biomechanics. It concerns the primary explosive effect. It is defined as pure shock wave of the explosion. The physical behavior of the shock wave when interacting with different types of tissue and, in particular, the subsequent transitions of the shock wave, have barely been investigated. The transition of the shock wave into other materials is the focus of the research Therefore, the aim of the investigations is the development of a multidisciplinary method to investigate shock wave behavior in various generic tissue simulants under the most reproducible conditions possible with realistic loads in an experimental test series with short set-up times. An autoclave is used to generate the pressure waves. A simplified torso model consisting of ballistic gelatin is used as a simulant. In this paper, the influence of protective equipment on the pressure load in the tissue simulant is investigated. For this purpose, consecutive test setups are used. First, the behavior of ballistic gelatin as a tissue simulant is investigated. Then, the simplified torso model is covered with typical combat clothing consisting of four layers. Afterwards a currently used UHMWPE ballistic protective plate is placed in front of the simplified torso model. Finally, the combat clothing and the protective plate are examined in combination. Three cast-in pressure sensors are used as measuring devices, as well as an acceleration sensor attached to the protective plate. The experiments show that the maximum overpressure in a model rotected by combat clothing and the protective plate can be reduced by 95%. However, the propagation speed of the shock wave within the simplified torso model increases from 1535.5 m/s to 2204.5 m/s. This shows that even protective equipment, which is not primarily intended to protect against blast, offers a significant reduction in the pressure load in the protected area. On the one hand it is caused by the media transition from air to PE and the resulting higher reflection of the acceleration of the transmitted wave within the simulant. On the other hand, it is also reduced due to the damping and dispersion caused by the clothing layers. T2 - 16th International Personal Armour Systems Symposium CY - Dresden, Germany DA - 11.09.2023 KW - Shock wave generator KW - Blast injury KW - Pressure wave KW - Experimental setup PY - 2023 SN - 978-9-0829-2732-0 SP - 178 EP - 187 CY - Brüssel AN - OPUS4-58640 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Seeber, Henrik A1 - Grobert, Steffen A1 - Krentel, Daniel A1 - Hauer, Thorsten T1 - Influence of Torso Protective Equipment on Intracorporeal Shock Wave Behavior N2 - In the field of explosive reactions, there is a type of explosive effect that lacks a sufficient database and reproducible experiments regarding biomechanics. It concerns the primary explosive effect. It is defined as pure shock wave of the explosion. The physical behavior of the shock wave when interacting with different types of tissue and, in particular, the subsequent transitions of the shock wave, have barely been investigated. The transition of the shock wave into other materials is the focus of the research Therefore, the aim of the investigations is the development of a multidisciplinary method to investigate shock wave behavior in various generic tissue simulants under the most reproducible conditions possible with realistic loads in an experimental test series with short set-up times. An autoclave is used to generate the pressure waves. A simplified torso model consisting of ballistic gelatin is used as a simulant. In this paper, the influence of protective equipment on the pressure load in the tissue simulant is investigated. For this purpose, consecutive test setups are used. First, the behavior of ballistic gelatin as a tissue simulant is investigated. Then, the simplified torso model is covered with typical combat clothing consisting of four layers. Afterwards a currently used UHMWPE ballistic protective plate is placed in front of the simplified torso model. Finally, the combat clothing and the protective plate are examined in combination. Three cast-in pressure sensors are used as measuring devices, as well as an acceleration sensor attached to the protective plate. The experiments show that the maximum overpressure in a model protected by combat clothing and the protective plate can be reduced by 95%. However, the propagation speed of the shock wave within the simplified torso model increases from 1535.5 m/s to 2204.5 m/s. This shows that even protective equipment, which is not primarily intended to protect against blast, offers a significant reduction in the pressure load in the protected area. On the one hand it is caused by the media transition from air to PE and the resulting higher reflection of the acceleration of the transmitted wave within the simulant. On the other hand, it is also reduced due to the damping and dispersion caused by the clothing layers. T2 - 16th International Personal Armour Systems Symposium CY - Dresden, Germany DA - 11.09.2023 KW - Shock wave generator KW - Blast injury KW - Pressure wave KW - Experimental setup PY - 2023 AN - OPUS4-58639 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -