Subglacial explosion is mainly used for ice breaking operation, and it is widely used in daily production and life, military, scientific research and other fields. When using numerical analysis software to deal with the ice breaking problem of nearfield underwater explosion, this paper takes the damage of shock wave load and bubble jet load to the ice layer as the research object. Aiming at the meso damage of ice layer under near-field underwater explosion, a numerical model of shock wave ice layer and bubble ice layer coupling effect is established based on one-dimensional stress wave propagation theory, The meso evolution process of ice damage under near-field underwater explosion is analyzed. Compared with the empirical formula and numerical calculation results, the law and mechanism of ice damage and crack propagation under near-field underwater explosions are obtained.
The vibration and noise of the transmission system has become the main factor hindering the improvement of gear efficiency and accuracy. In order to investigate the influence of different lay-up materials on the vibration and noise reduction of transmission system, this paper is based on the topology optimization of macro and micro elastic metamaterials to obtain the optimal unit cell configuration of elastic metamaterials. The analysis compares the vibration noise of the gearbox under different cover layers, and the results show that the elastic metamaterial layer has a better suppression effect on the vibration noise than the traditional constrained damping layer, which provides a reference for the subsequent design of vibration and noise reduction comparative analysis and proposes further research.
The kinematic response of the reinforced cylindrical hull has a significant impact on the comfort of the ship's occupants. The dry modal data are first decomposed into multiple IMF signals using the empirical modal decomposition method, and the noise and trend terms in the signals are removed, with the energy increment method. The LSCE method is then used to plot the frequency stability of the modes at different measurement points, and after eliminating spurious modes, the final identified model intrinsic frequencies are obtained; Finally, the effectiveness of the analytical solution in identifying the inherent frequencies of the model is verified by comparing it with the inherent frequencies obtained using the analytical solution.
Self-excited oscillating pulsed cavitation jet is a phenomenon in which cavitation bubbles are generated by oscillation in the unique structural characteristics of the nozzle, and the impact effect of the jet is increased by collapse of the cavitation bubbles. Based on the structure parameters of the traditional Helmholtz and organ pipe single chamber self excited oscillating pulsed nozzles, Helmholtz + Helmholtz, Organ pipe + Organ pipe and Helmholtz + Organ pipe dual chamber self-excited oscillating pulsed nozzles with different structures are established in series, and VOF (Volume of Fluid) is selected for multiphase transient flow calculation. The external flow field of dual chamber is studied to obtain the best combination nozzle.
The dynamic characteristics of the ship's plate frame is an important factor in determining the structural quality of the ship. In this paper, the structural impact response spectrum and the deformation displacement of the plate structure under the blast load are used as indicators to assess the impact resistance. A finite element model of the plate structure and flow field is established. The dynamic characteristics of composite laminated plates with different characteristics under the underwater explosion loads are analyzed. The results show that the elastic modulus and Poisson’s ratio of the composite laminated, the number of layers, the fiber laying angle, all affect the mechanical properties and impact resistance of the plate structure.
The submarine whip motion induced under underwater blast load is very serious to its destructive impact and threatens the survival condition of the submarine. Therefore, the whip dynamic response of cylindrical shell structure under the underwater blast load is experimentally investigated. First, the type of submarine transverse bulkhead is selected as the experimental object. Next, strain gauges are selected as the measurement sensors for the experiments, for a total of 14 evenly distributed measurement points for data acquisition and measurement of the strain response of the reinforced cylindrical shell under the underwater blast load. Ultimately, the variation pattern of strain values with time generated strain at each point location is derived, and the location of the most vulnerable cylindrical shell structure is obtained.
The submarine whip motion induced under underwater blast load is very serious to its destructive impact and threatens the survival condition of the submarine. Therefore, the whip dynamic response of cylindrical shell structure under the underwater blast load is experimentally investigated. First, the type of submarine transverse bulkhead is selected as the experimental object. Next, strain gauges are selected as the measurement sensors for the experiments, for a total of 14 evenly distributed measurement points for data acquisition and measurement of the strain response of the reinforced cylindrical shell under the underwater blast load. Ultimately, the variation pattern of strain values with time generated strain at each point location is derived, and the location of the most vulnerable cylindrical shell structure is obtained.
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