Blast waves generated from the muzzles of weapons may exert negative effects, such as shock waves and impulse noise. If the weapon is fired with a muzzle brake, these effects are recognized to be more severe. This paper discusses the influence of the muzzle brake on certain aeroacoustic noise characteristics based on numerical simulations and a corresponding experiment. The impulse noise, which is induced by complex jet flows discharging from small caliber rifles with muzzle brakes, is focused in this study. Computational fluid dynamics (CFD) and computational aeroacoustics (CAA) are combined to calculate the muzzle flow field and jet noise for cases with and without a muzzle brake, and then the data sets are carefully compared. The simulations indicate that the muzzle brake alters the muzzle flow field and directional distribution of the jet noise compared to a rifle sans muzzle brake. Deviations less than 7.6% between experimental data and simulation results validate the simulation model. The results presented in this paper may provide a workable reference for the prediction of muzzle noise and the optimization of muzzle brake designs.
To research the strength of composite material barrels, based on the CDM theory, an energy-based stiffness degradation method is proposed to predict the progressive failure properties of steel- fiberglass/ epoxy composite laminated barrels. Three failure modes of fiberglass/ epoxy composites, including fiber breakage, matrix cracking and fiber/matrix interface shear failure are considered in the present model. A 3D finite element technique including the multiframe restart analysis is employed to conduct the progressive failure analysis. The results indicate that the mode considering the stiffness degradation and progressive failure of the material is more reasonable on researching the strength of composite material barrels. The strength of composite material barrels in this paper is influenced by the fiber strength mainly.
To investigate the wounding effects in human on the basis of the similarity theory, by taking the temporary cavity as the research object, through the analysis on the forming of cavity and its physical process, main influencing factors effecting temporary cavity are obtained, which can provide a good theoretical basis for similarity research in wounding ballistics in the future, and the killing effect of the high speed steel ball is more deeply described.
The automatic weapons suffered the coupling load of in-bore pressure and temperature load during firing, which exerted a serious influence on the gun barrel life. Suppose the gun barrel was thick wall cylinders, the relations among the radial stress, tangential stress, longitudinal stress and equivalent stress in thick wall cylinders enduring interior pressure and temperature loads were analyzed by traditional analytic method, 2D finite element method (FEM) and 3D FEM respectively. Boundary effects of the stress field in thick wall cylinders were also analyzed. The obtained results showed that 3D FEM is suitable for the analysis on boundary effects, and the coupling stress could be designed and optimized by adjusting the interior pressure or temperature loads.
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