Prediction of Peak Overpressure of Charge Enveloped by Polymer Matrix Composite: Theoretical Modeling and Experimental Verification

This study aimed at elucidating some characteristics of the shock wave overpressure generated by a non-traditional layered charge comprising an inner high-energy explosive and an outer polymer matrix composite. Two models for predicting the peak overpressure (Δpm) of the charge were established, namely, a model based on the initial parameters of the blast wave, and a model considering the weakening of the explosion energy through the introduction of polymer matrix cladding. The overpressure of a typical layered charge was experimentally measured for model validation. It was found that the difference between the Δpm predicted by the two models and the experimental data is less than 15.12% and 14.17%, respectively. The model that was established based on the conservation of energy law, is in best agreement with the experimental data under different cladding/charge mass ratios (αm). The model that was based on the initial parameters of the blast wave obtained a low predicted value when αm was 0.4-0.8, which is attributed to the non-uniformity of the gas-solid mixture during the explosive dispersion stage.

Nanoscopic fuel-rich thermobaric formulations: Chemical composition optimization and sustained secondary combustion shock wave modulation

Advanced thermobaric explosives have become one of the urgent requirements when targeting caves, fortified structures, and bunkers. Highly metal-based systems are designed to exploit the secondary combustion resulted from active metal particles; thus sustained overpressure and additional thermal loadings can be achieved. This study, reports on a novel approach for chemical composition optimization using thermochemical calculations in an attempt to achieve the highest explosion power. Shock wave resulted from thermobaric explosives (TBX) was simulated using ANSYS(®) AUTODYN(®) 2D hydrocode. Nanoscopic fuel-rich thermobaric charge was prepared by pressing technique; static field test was conducted. Comparative studies of modeled pressure-time histories to practical measurements were conducted. Good agreement between numerical modeling and experimental measurements was observed, particularly in terms of the prediction of wider overpressure profile which is the main characteristics of TBX. The TBX wider overpressure profile was ascribed to the secondary shock wave resulted from fuel combustion. The shock wave duration time and its decay pattern were acceptably predicted. Effective lethal fire-ball duration up to 50ms was achieved and evaluated using image analysis technique. The extended fire-ball duration was correlated to the additional thermal loading due to active metal fuel combustion. The tailored thermobaric charge exhibited an increase in the total impulse by 40-45% compared with reference charge.