Papers by Keyword: Dynamic Numerical Simulation

Abstract: Extensive concerns on environmental protection have provoked low-carbon buildings to be the mainstream of building construction worldwide, and wooden structures in this sense outperform other structural forms. Wooden-concrete hybrid structures featuring distinct wooden and concrete stories typically exhibit uneven stiffness distribution along the structure height; in particular, abrupt stiffness changes occur at the wood-concrete transition stories. Therefore, structural designing of such hybrid structures must consider a stiffness amplification effect in the static structural calculation as well as complicated procedures in the dynamic analysis. To determine an appropriate amplification factor for design purpose, this study employed a dynamic numerical approach to determine the displacement response of wooden-concrete hybrid buildings and compared the results with the displacement response obtained from static analyses. According to the results, it is found that the appropriate amplification factor should beα= f (x) = 0.47x + 1.00.αcan be valued 1.94 at 2nd floor, 2.41 at 3rd floor and 2.88 at 4th floor. The results may serve as a reference for seismic designing of wooden-concrete hybrid structures.

Abstract: 3D numerical simulation is carried out for the water flow in stilling basin with X shaped flaring gate pier when the radial gate uses four different opening velocities. The space-time change law of hydraulic characteristics is obtained. The water level in the stilling basin is relatively higher while using lower opening velocities during the processes. The negative pressure exists on weir surface while the relative opening degree is less than 0.55; the maximal pressure on the slab of ogee section and stilling basin increases and moves to downstream with the gate opening. The results can provide important basis for shape optimization of practical engineering.

Abstract: The cut-off valve based on pilot valve controlling is a new kind of valve which opens and closes fast and has low driving energy consumption. Because of the complexity of the internal flow and uncertainty of the internal pressure, there is uncertainty in the design of the key structure. We simulate the whole opening process of the valve under different key structural dimensions with Fluent Dynamic Mesh and UDFs, and we do experiments to authenticate simulation results. The turn-on time we get from the simulation is the same as that from experiments under the valves actual operating conditions, in other words, the simulation results are correct, so we can identify the valve flow and get the internal pressure data which provides a reliable basis for the design of the key structural dimensions.

Abstract: The RNG k-e model and dynamic mesh technology are applied to simulate the unsteady flow of flaring gate pier and stilling pool during the process of radial gate opening. The space-time change law of hydraulic characteristics is obtained. The negative pressure exists on weir surface while the relative opening degree (e) is less than 0.3; the maximum pressure on the slab of stilling pool increases and moves to downstream with the gate opening; the velocity near the slab is relatively larger in the foreside of stilling pool and reaches the maximum value at e=0.5. The numerical results agree well with the experimental data, which shows the method is effective and can provide reference for shape optimization of practical engineering.

Abstract: Joints can reflect and transmit stress waves, thus joints affect rock fracturing, and accordingly they could affect blasting efficiency. In this paper, numerical and experimental investigations have been implemented and the effect of joints on wave propagation and rock fracturing has been discussed. A dynamic numerical model of jointed rock mass has been established by using finite difference method. The simulation results show that as joints are parallel to wave propagation, the corresponding rock damage zones increase. Blasting experiments by using artificial joints have been carried out. Generally the experimental results agree with our numerical results.

Abstract: A crater blasting model of rock with pre-existing defects under blasting loads is established by using finite difference method. The defects are saturated with water and are randomly distributed. The defects include voids, pores and small open joints. A shock equation of state (EOS), obtained from the existing test results, is employed for the granite near the explosive charge, and for the granite far from the charge, a linear EOS is applied. A modified principal stress failure criterion is applied to determining the granite statuses. The granite dynamic strengths, which increase with strain rate, are calculated from the existing test results. The simulation results show that under blasting, the strength of wet rock is lower than that of dry rock.

Abstract: Polishing is an important technics processing in order to obtain the high quality surface of mould in industry mould manufacture. For the moment, polishing of the free-form curved surfaces of mould is performed by manpower. So it is important to research gasbag polishing technology. This paper has been developed dynamic numerical simulation for gasbag polishing process based on the new type of polishing tools by FEM. On the material removal theory, influence of the shape of the structure of the gasbag, angular velocity and the air pressure inside the air gasbag on the campaign polishing process are explored. It can be used to provide technology support to establish polishing process database.