Simulation and Measurements of Small Arms Blast Wave Overpressure in the Process of Designing a Silencer
Abstract Simulation and measurements of muzzle blast overpressure and its physical manifestations are studied in this paper. The use of a silencer can have a great influence on the overpressure intensity. A silencer is regarded as an acoustic transducer and a waveguide. Wave equations for an acoustic dotted source of directed effect are used for physical interpretation of overpressure as an acoustic phenomenon. Decomposition approach has proven to be suitable to describe the formation of the output wave of the wave transducer. Electroacoustic analogies are used for simulations. A measurement chain was used to compare the simulation results with the experimental ones.
Cooperation of the Spatial Interpolation Algorithm for the Contour Map of the Shockwave Overpressure Field
Traditionally, the peak overpressures of multi-point shockwave are obtained through the sensor array by using the electrometric method, and then the surface interpolation is carried out by the mathematical model to draw the contour lines of the shockwave overpressure field. The cross-validation method of the mean absolute error (MAE), mean relative error (MRE), and root mean square error (RMSE) was proposed in this study to achieve high precision and effective interpolation of the contour lines. The quantitative test of Kinney-Graham Formula was verified, and the peak overpressures of the multi-point shockwave of a 7.62-mm caliber gun and a naval gun were obtained through the sensor array based on polar coordinate. Then, the shockwave overpressure field was interpolated by the inverse distance weighted (IDW) interpolation, the ordinary kriging interpolation(OK), the radial basis function (RBF) interpolation, and the cubic spline (CS) function interpolation, Finally, cross-validation analysis was performed on MAE, MRE, and RMSE. Results demonstrate that the MAE of the RBF interpolation is 0.038, and the MRE is 0.001. The error is smallest, the accuracy is highest, and the interpolation effect is closest to the shockwave field model. The OK interpolation is close to the RBF interpolation. The MRE of the CS interpolation is 0.254, which is relatively large. The RMSE of the IDW interpolation is 14.268, which is abnormal. The RBF interpolation is the optimal interpolation algorithm for the shockwave overpressure field, which provides a reference for the contour drawing of the shockwave overpressure field. __________________________________________________________________________________________
Acoustic Directivity Patterns for Army Weapons
Abstract : This report describes tests conducted by this investigation on 12 types of Army heavy weapons at Fort Sill, OK, and the development of precise sound-pressure level contours (directivity patterns) for Army weapons currently in use. The data obtained during these tests was also used to compile tables relating the charge weight to an equivalent weight of C-4 plastic explosive. In addition, this investigation determine that elevation has little influence on weapon directivity patterns; the major factor affecting weapon directivity patterns was the muzzle brake, which causes directivity patterns to become almost circular. The exceptions were recoilless rifles. Weight equivalency tables were found to be a function of tube size, with the longest tubes being the quietest, since the charges within them are the most contained.