Advanced Materials Research Vols. 753-755

Abstract: The double-walled steel vessel filled with insulation powder in the space between two walls was used to minimize heat transfer by radiation and conduction in cryogenic storage tank. And, evaluation of the insulation effect by the thermal conductivity of perlite powder and the effect of heat flux by welding conditions were carried out with insulation analysis of double-wall. The solid supports were also used to bear the weight of the inner container. Furthermore, thermal and structural analysis of the tank was performed to study the effect of vacuum and weldment geometry of the internal supports. If the degree of vacuum were low, the thermal conductivity of perlite increases rapidly and the heat flux should be increased in proportion to the thermal conductivity. Two types of solid supports did not show significant differences in the aspect of working stress or heat flux. Therefore, it is considered that the heat flux is less sensitive against the weldment geometry.

Abstract: In this paper, a conjugated heat transfer problem of conduction and convection in the concentric tubes with longitudinal fins was studied by means of numerical simulation. 3D temperature and fluid flow fields were simulated for three-split concentric tube recuperator with longitudinal fins for laminar fluid flow. The numerical simulation results show that the ratio of , which is the function of the angle of fins and axis, and solid thermal conductivity, decreases quickly as longitudinal length increases. If the conduit is long enough, the ratio of can be neglected. The ratio of Nusselt number and the ratio of friction factor increase as the angle of fins and axis increases, and the ratio of Nusselt number increases more quickly than that of the friction factor for the same angle.

Abstract: A method for studying the characteristics of electromagnetic railguns exterior ballistic trajectory is present. For electromagnetic railguns high muzzle velocity and wide range,which make it cover the whole near space, an proper atmospheric environment model and an mathematical model of motion are proposed to describe the railguns exterior ballistic trajectory. By comparing the trajectory performance and velocity variation between electromagnetic railgun and conventional gun, railguns advantage in velocity and range as well as its lethality over conventional gun is testified and its potential application value is shown. Results indicate that electomagnetic railgun has the capability to intercept the missile or other type of military targets, and it is critical to get a tradeoff between mass of projectile and muzzle velocity.

Abstract: Overdrive transmission is easy to rattle. In gear system, rotation speed is one of the important parameters affecting gear rattle. A numerical method for gear rattle simulation at different rotation speed is proposed, which combines the model of gear rattle with the actual motion of gears. Aiming at the relative velocity, which is one of the most important parameters to evaluate the intensity of gear rattle, computational simulation and experimental verification is finished about the influence of different rotation speed on gear rattle with error excitation under overdrive. The experiment and simulation results show that with the rotation speed rising, the amplitude of relative velocity of gear rattle increases, which indicates severer gear rattle.

Abstract: The effect of inner-rod parallel misalignment in a 9-GHz open coaxial resonator is studied by means of the software CST microwave studio. Results show that the parallel misalignments between the inner rod and outer wall have substantial influences on the field profile, resonant frequency, and Q factors of an open coaxial resonator. So in the practical of engineering applications, we should try to avoid the occurrence of eccentric between the inner rod and outer wall due to technological factors.

Abstract: Blade is one of the main parts of aircraft engine. Its dynamic characteristics will produce important influence on the work efficiency and the operation reliability of the turbine engine. The paper used the theory of finite element to do modal simulation analysis on the dynamic characteristic of blade flutter, aiming at the phenomenon of serious blade vibration in the process of turbine engine running. Firstly, the paper generated a three-dimensional model by using the software UG. Then the three-dimensional model was leaded into the finite element analysis software ANSYS. Simulation analysis of the model was carried out by using the Workbench module of ANSYS software. Finally, we got the former six order natural frequencies and vibration modes of the blade. In addition, we got the blade's vibration characteristics. The results of the simulation could provide numerical basis for the blades optimization design and vibration safety inspection.

Abstract: Structural modified crack model is deduced to analyze modal parameters of the damaged beam by using of perturbation method. Firstly, the optimal fitting formula of inertia moment at the damage location is proposed to consider damage's influence on structural stiffness and mass matrix. Then, the solutions of the first and second vibration perturbation equations are deduced. Compared with experimental results of simply-supported cracked beams, this method's reliability is proved.

Abstract: The effect of steel, copper and aluminum interlayer on the stress wave propagation of ceramic/ Ti6Al4V armors were studied by traditional Split Hopkinson Pressure Bar system in this paper. Based on the SHPB experimental results, the stress wave propagation mechanism and energy absorption in tri-layered structure were discussed. Compared to ceramic/Ti6Al4V structure without interlayer, the steel, copper and aluminum interlayer could attenuate the transmission stress level and greatly increase the energy absorption of the structure. Due to the high acoustic reluctance of steel and copper interlayer, the reflected shock wave was in compressed situation and extended a tri-axial compressive stress within the ceramic which could improve the anti-penetration properties of ceramic plate. The numerical modeling studies of ballistic testing were carried on, and then the energy densities were compared. The results showed the steel and copper interlayer could increase the energy absorption of ceramic and improve the anti-penetration of ceramic plate. The three kinds of interlayer structures all could attenuate transmitted energy and decrease the residual penetration.

Abstract: Magnetic nanoparticles (MNPs) have been considered as potential therapeutic agent carrier for the magnetic targeted-drug delivery in the fight against cancer. Trajectories of MNPs in the blood vessel determine the capture and retention ratio, and the final effectiveness of the treatment. In the present study, a theoretical model of MNPs trajectory is deduced at first. Then two kinds of magnets are proposed, and their magnetic field distributions are calculated through the finite element method software of ANSYS. Using the model and magnetic field inputs, the MNPs trajectories are determined, and the influences of the MNP diameter (R_p), the blood flow velocity (v_f) and magnetic field intensity (H) on the trajectories are clarified finally. It is found that the proposed method combining the theoretical model and numerical simulation is feasible. The closed magnetic circuit with concave-convex poles has better MNPs retention ratio than that of the open magnetic circuit because it has higher H and Grad (H). Large R_p, low v_f, and high H are good to capture the MNPs. Especially v_f and H are critical parameters for the retention ratio of MNPs, and high v_f and low H may let MNPs escape the magnetic field region.

Abstract: Magnetic targeted-drug delivery system (MTDs) works as a promising cancer treatment approach, and is entering the mainstream. It applies an external magnetic field to attract and guide the magnetic nanoparticles (MNPs) carrying treatment agent and targeted antibodies to the lesion region. Its key factor is the high gradient magnet. Here three types of magnets are proposed, i.e., open circuit magnet, close circuit magnet with planar poles, and close circuit magnet with concave-convex poles. And then their magnet field distributions are calculated through the finite element method (FEM). The simulation results are compared with each other and the measurement of Gauss Meter for the manufactured magnet, and the primary experimental result is also reported. It is found the closed magnet circuit with concave-convex poles shows about 2.0 and 1.2 times higher magnetic field intensity (H) than the open magnet circuit and the close magnet circuit with planar poles, respectively. Most important is it owns largest Grad (H) (1.0 e6 A/m²) among three magnets. The simulation agrees well with the measurement, and the primary experimental results also show the magnet can attract MNPs efficiently. Hence the calculation enables provide with credible input for the further trajectory simulation for MNPs.