Abstract: An example of horizontal cracks on the surface of reinforced concrete side-columns is presented. Based on the finite element analysis , a conclusion is made that those cracks are caused by the frame’s deformation under changing temperature. Then the way to calculate the width of such cracks is raised. The design method for the reparation by sticking carbon fiber materials to the column is also developed. Those methods are applicable in realistic works.
Abstract: Algorithms for generating and distributing random 3D sphere coarse aggregates were proposed. The 3D finite element mesoscale concrete model, which consists of mortar matrix and coarse aggregates, was established based on the theory of background element and material identification. The interfacial transition zone was simplified as a kind of contact between elements. Based on this model, continuous finite element code was used to simulate the process of rigid projectiles perforating concrete targets and the effect of 3 different coarse aggregate types on residual velocities was analyzed. This work indicates that the strength and density of coarse aggregates affects the residual velocity under lower and higher impact velocity respectively.
Abstract: Nanowelding system is set up to investigate the welding process of nickel electrodes to single walled carbon nanotubes (SWCNTs) with molecular dynamics method. This system consists of C-C, C-Ni, Ni-Ni subsystems. The interaction of C-C, C-Ni Ni-Ni are modeled by adaptive intermolecular reactive empirical bonder order (AIREBO) potential, Lennard-Jones (LJ) potential, as well as embedded atomic method (EAM) model respectively. The dynamic process of nanowelding at different temperatures and times is analyzed and described completely at atomistic length scales. The simulation results indicate that the nanowelding could be accomplished at 1450k which is far lower than the melting point of nickel.
Abstract: Composites of continuous glass fiber reinforced impact polypropylene copolymer (IPC) were prepared by using a cross-head impregnation mold by a self-designed die fixed on a single screw extruder, and were chopped into Long fiber/IPC pellets approximately 12 mm in length. The effect of preheat temperature and pulling speed on the mechanical properties of the composites were studied and micrographs of fracture surface of impact specimens for the composites were investigated by scanning electron microscope (SEM). Mechanical properties of the composites were best at 200 °C of the preheated temperature, for the better interfacial adhesion between glass and matrix resin, and that proved by the SEM. Meanwhile, mechanical properties of the composites decreasing with the increasing of pulling speed, for the impregnation effect degraded.
Abstract: According to the principle of internet integration systems, the accurate interactive TV equipment is designed. On the basis of establishing the model of animation scene to be processed, the 3D video equipment is assembled in a signal and image processing by using the application software signal and image processing systems provided by game systems. The virtual image of the components of accurate video equipment is implemented either from top to bottom or reversely, providing a basis for humane care in children postoperative recovery of this equipment.
Abstract: Natural deposit of loess has large pores and weak cementation, resulting weak shear strength and large deformation under external stress, which is the major engineering problem of the loess ground. By adding suitable amount of ordinary Portland cement to treat the loess can increase the shear strength to meet the needs of ground safety. In this study, triaxial test is carried out to evaluate improvement of the unconfined compressive strength and shear strength of loess after adding certain amount of Portland cement, also by scanning electron microscope observation and analysis of SEM images using image processing system, it is found that the cement improved microstructure of loess, increased clay content and enhanced cementation, thus increased the shear strength.
Abstract: Corrosion of reinforcement is one of the most important factors in causing the damage to reinforced concrete structure and the inestimable economic loss and major security risk to a large number buildings with reinforced concrete structure. In order to overcome the disadvantage of previous service reinforcement which can only be carried out by sizing detection not quantification, this paper puts forward to a new method to evaluate non-destructive quantification of corrosion degree of reinforcement based on the combination of electrochemical detection and finite element analysis, thus the effective corresponding can be produced among reinforcement corrosion rate, potential signal and reinforced concrete structural distortion. The relation among corrosion current density and potential characteristic parameters as well as corrosion ratio has been established. Through the finite element analysis technique and the combination with the case analysis, the relation model between the strain rate of concrete beams and detection signal has been built; the forecasted empirical formula for change of strain value of tested reinforcement has been given And by means of verifying the reliability of model with data of previous experiments, the quantitative calculation of reinforcement corrosion degree has been realized, which lays the technical foundation for the research and development of non-destructive detection equipment of corrosion of reinforcement.
Abstract: The aerodynamics of the helicopter rotor is one of the most elating and exigent tribulations faced by the aerodynamicists today. Study through flow visualization process plays a key role in understanding the airflow distinctiveness and vortex interaction of the helicopter main rotor blade. Inspecting and scrutinizing the effects of wake vortices during operation is a great challenge and imperative in designing effective rotor system. This study aimed to visualize the main rotor airflow pattern of the Hirobo-FALCON 505 controllable subscale helicopter and seek for the vortex flow at the blade tip. The experimental qualitative data is correlated with quantitative data to perform scrupulous study on the airflow behavior and characteristics along with its distinctiveness spawned by the main rotor blade. Simulation using design software is performed in analogous stipulations to endow with comparability between the flow visualization results. Throughout the blade span several dissimilar flow patterns have been identified. The main rotor hub has turbulent flow at its center due to low energy of air amassed in this region whereas in the middle portion of the rotor blade, the air encompasses high kinetic energy with a clear straight streamline pattern.
Abstract: This numerical study examines a three-dimensional liquid-metal magnetohydrodynamic flow in a hairpin-shaped electrically-conducting duct with a square cross-section under a uniform magnetic field applied perpendicular to the flow plane. Predicted is detailed information on fluid velocity, pressure, current, and electric potential in the magnetohydrodynamic duct flow. Higher velocities are observed in the side layers in the inflow and outflow channels, yielding M-shaped velocity profiles. More specifically, in the present study the axial velocity in the side layer near the partitioning wall is higher than that near the outer walls because of the current features therein. In the turning segment, a large velocity recirculation is observed at the entrance of the outflow channel caused by the flow separation, yielding complicated distributions of the electric potential and current therein. The pressure almost linearly decreases along the main flow direction, except for in the turning segment.