As the main launch energy of barrel weapon, the dynamic mechanical properties of gun propellant is very important to evaluate the launch safety. Through the transverse drop hammer impact damage test at room temperature and the initial dynamic vivacity ratio test of the propellant, the crack growth law and the fracture degree of the damaged propellant were obtained separately. Based on the Hertz-Mindlin bonding contact model, the discrete element mechanical model of the rosette 19-hole gun propellant was established, and the transverse drop hammer impact damage simulation was carried out. The damage mechanism of the bonding contact model and the fracture degree of the damaged propellant were acquired, which were also verified by tests. The results show that the bonding contact model can accurately describe the impact damage law of propellant. The research results of this paper can be used to predict the abnormal chamber pressure caused by fracture of propellant, provides a research means for mechanical property evaluation of 3D printing gun propellant, and lays a theoretical foundation for quantitative evaluation of launch safety.
In this paper, the magnetic-structure-acoustic multi-physical field model of S13-M400/10 distribution transformer is established through the FEA software. The harmonic response analysis method is used to study the winding vibration and transmission characteristics of the transformer. The simulation results show that the flux leakage distribution of windings on each core column is mainly determined by the current flowing through these windings. The radial and axial acceleration distributions of the windings are U shape and M shape respectively along the winding height. The acceleration of B phase windings is smaller than that of A and C phase windings. The vibration of the oil tank surface is concentrated in its middle and lower part. The tank side vibration is mainly affected by the vibration of the nearest phase windings, while the tank front vibration is affected by the vibration of the three-phase windings together. This study is of great significance for further studies of the vibration characteristics of the transformer under unbalanced load and proposing the vibration reduction and noise reduction measures for the distribution transformer.
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