Mathematical Simulation on Self-tuning Fuzzy Controller for Small Cylindrical Object Navigating near Free-surface

AbstractBased on the adaptive fuzzy control theory, a self-regulating fuzzy controller is designed for a small cylindrical object navigating near free-surface to minimize wave disturbance and to keep the object move in the desired depth. First, the near free-surface dynamics model of the cylindrical object is presented with the first and second order wave forces. Second, math simulation is introduced to testify the validity of the control method. The results obtained by a series of mathematical simulations demonstrate that the self-tuning fuzzy depth controller performs well in stabilizing the near-surface navigating object and in keeping it in the expected depth during the free-surface wave disturbance

Effect of CeO2 on Impact Toughness and Corrosion Resistance of WC Reinforced Al-Based Coating by Laser Cladding

WC reinforced Al-based coating with added CeO2 was prepared on the surface of S420 steel by laser cladding. The microstructure and structure of the coatings were analyzed by scanning electron microscope, X-ray diffractometer and optical profiler. The mechanical properties and corrosion properties of the coatings were studied by microhardness tester, friction and wear tester, Charpy impact tester, and electrochemical workstation. The results show that the coating is mainly composed of Al-phase, continuous-phase, and hard reinforced-phase WC, and the coating and substrate show good metallurgical bonding. When the content of CeO2 is 1%, the fine grain strengthening effect is obvious, and the impact toughness of the coating is obviously improved. Appropriate amount of rare earth CeO2 can significantly improve the hardness of the coating. When the content of CeO2 is more than 1%, the wear resistance of the coating decreases. The coating prepared with different CeO2 content has higher impedance and corrosion resistance than that of the substrate. At 1% CeO2 content, the coating has the best corrosion resistance

Numerical Simulation of the Overall Flow Field for Underwater Vehicle with Pump Jet Thruster

AbstractThe flow field numerical simulation of underwater vehicle with pump jet thruster was performed using the commercially available CFD software FLUENT based on the Reynolds averaged Navier Stokes Equations and k-epsilon RNG turbulence model. Multiple reference frames (MRF) was used to associate the interior flow field of the pump jet thruster and exterior flow field of the underwater vehicle. Validity of the CFD model is verified using data from experiment. Characteristic of the overall flow field was obtained and pressure distribution of the propulsion was also given. The simulation results could be regarded as an important reference in the optimal design of pump jet thruster and the hydrodynamic characteristics of underwater vehicle

Study on the Penetration Performance of a 5.8 mm Ceramic Composite Projectile

The penetration ability of a 5.8 mm standard projectile can be improved by inserting a ZrO2 ceramic ball with high hardness, high temperature, and pressure resistance at its head. Thereby, a ceramic composite projectile can be formed. A depth of penetration (DOP) experiment and numerical simulation were conducted under the same condition to study the armor-piercing effectiveness of a standard projectile and ceramic composite projectile on 10 mm Rolled Homogeneous Armor (RHA) and ceramic/Kevlar composite armor, respectively. The results show that both the ceramic composite and standard projectiles penetrated the armor steel target at the same velocity (850 m/s). The perforated areas of the former (φ5 mm & φ2 mm) were 2.32 and 2.16 times larger, respectively, than those of the latter. The residual core masses of these two projectiles (φ5 mm & φ2 mm) were enhanced by 30.45% and 22.23%. Both projectiles penetrated the ceramic/Kevlar composite armor at the same velocity (750 m/s). Compared with the standard projectile, the residual core masses of the ceramic composite one (Ø5 mm & Ø2 mm) were enhanced by 12.4% and 3.6%, respectively. This paper also analyzes the penetration mechanism of the ceramic composite projectile on target plates by calculating its impact pressure. The results show that the ceramic composite projectile outperformed the standard projectile in penetration tests. The research results are instructive in promoting the application of the ZrO2 ceramic composite in an armor-piercing projectile design

Study on the Penetration Performance of a 5.8 mm Ceramic Composite Projectile

The penetration ability of a 5.8 mm standard projectile can be improved by inserting a ZrO2 ceramic ball with high hardness, high temperature, and pressure resistance at its head. Thereby, a ceramic composite projectile can be formed. A depth of penetration (DOP) experiment and numerical simulation were conducted under the same condition to study the armor-piercing effectiveness of a standard projectile and ceramic composite projectile on 10 mm Rolled Homogeneous Armor (RHA) and ceramic/Kevlar composite armor, respectively. The results show that both the ceramic composite and standard projectiles penetrated the armor steel target at the same velocity (850 m/s). The perforated areas of the former (φ5 mm & φ2 mm) were 2.32 and 2.16 times larger, respectively, than those of the latter. The residual core masses of these two projectiles (φ5 mm & φ2 mm) were enhanced by 30.45% and 22.23%. Both projectiles penetrated the ceramic/Kevlar composite armor at the same velocity (750 m/s). Compared with the standard projectile, the residual core masses of the ceramic composite one (Ø5 mm & Ø2 mm) were enhanced by 12.4% and 3.6%, respectively. This paper also analyzes the penetration mechanism of the ceramic composite projectile on target plates by calculating its impact pressure. The results show that the ceramic composite projectile outperformed the standard projectile in penetration tests. The research results are instructive in promoting the application of the ZrO2 ceramic composite in an armor-piercing projectile design