Applied Mechanics and Materials Vol. 455

Abstract: The coupled model of groundwater flow and temperature is established, the thermal interaction of different pumping/injecting well groups arranged modes is simulated and analyzed, and the changing trend of groundwater temperature is predicted, which is to propose reasonable arranged wells programs. The thermal interaction of groundwater is compared and analyzed according to different arranged wells scheme, the pumping/injecting wells distance affect the thermal interaction significantly, the similar wells distance didnt affect significantly. The more number of pumping/injecting wells the thermal interaction is weaker, in order to delay the time of heat through, solve the problem of poor water recharge, we should increase appropriately the injecting wells number under keeping the pumping wells number constant.

Abstract: Concrete water cellar is an important facility to collect rainfall in Qingshuihe County of the Inner Mongolia Autonomous Region, China. The numerical simulation was carried out for the typical concrete water cellar structure using ABAQUS. Simulation results show that the maximum tensile stress and strain of cellar decrease with the cellar wall thickness increasing, and the strength of concrete C15 can meet the structural requirements of cellars with 10cm, 15cm, 20cm or 25cm wall respectively under the most unfavorable condition. The wall of cellar is thinner, its construction is more difficult in quality assurance. The wall of cellar is thicker, and its construction cost will increase. The construction of concrete cellar with 10cm wall is more difficult than those with thicker walls. It is suggested that the concrete water cellar with 15cm wall thickness is more suitable for being built in Qingshuihe County of the Inner Mongolia Autonomous Region, China.

Abstract: Based on the wind tunnel experiment for aerostatic force of section model of Jianghai direct ship channel bridge of Hongkong-zhuhai-macau great bridge in construction stage, one calculation program considering the geometric nonlinearity and aerostatic nonlinearity is prepared by using ANSYS parametric design language in order to calculate the nonlinear aerostatic response for long-span cable-stay bridges. Then, the FEA model of Jianghai direct ship channel bridge of Hongkong-zhuhai-macau great bridge in construction stage is established to analyze the three-dimensional nonlinear aerostatic stability. And the aerostatic response with different position of bridge is also calculated. The research result indicates that the aerostatic instability can not occur in Jianghai direct ship channel bridge of Hongkong-zhuhai-macau great bridge in its construction stage. And, the max torsion deformation, transverse and vertical displacement of construction stage occur in the terminal edge of both left and right span and decreases gradually near to main tower.

Abstract: Based on prophase research work, seismic checking for pier based on energy method is improved. The seismic input energy demand of pier is determined by using the seismic input energy response spectra and hysteretic energy dissipation spectra of sing-degree-of-freedom. Meanwhile, the Pushover Method is used to determine the hysteretic deformation capacity of pier. Then, based on the equilibrium principal between hysteretic deformation capacity and seismic input energy demand of pier, seismic checking for pier is carried on. Then, this improved seismic checking for pier based on energy method is applied in the design examples of piers. Comparing with the calculation of nonlinear time history analyses, it is known that improved seismic checking for pier based on energy method can evaluate the seismic performance of pier effectively. So, these valuable results can provide the meaningful reference for the seismic design of bridge engineering.

Abstract: Various kinds of damage may occur during the drilling of carbon fiber reinforced polymer composite (CFRP). To review the mechanism of CFRP drilling, a three-dimensional macro-mechanical finite element (FE) model was constructed for CFRP drilling based on FE software tool Abaqus. The workpiece was modeled as equivalent homogenous anisotropic material (EHAM) with elastic-failure behavior. Three-dimensional Hashin criterion was used to predict the material failure. The material was implemented in user subroutine VUMAT. The drilling process was analyzed and the thrust force with respect to cutting conditions was evaluated. The simulation shows that thrust force increase with feed rates while decrease with spindle speed, as agrees with experiment.

Abstract: Coiler is a very important equipment in the aluminum cold rolling production line. It plays an important role in improving the quality of the strip. In this essay, taken the aluminum cold rolling coiler drive system as the research object, in order to studying its dynamics characteristic, three-dimensional model has been built based on the finite element method. With the model, the aluminums weight has been verified, frequency and modal have been discussed, and the dangerous speed zone has been built by the first frequency. The result could serve as theoretical base for coiler design and manufacturing process.

Abstract: Based on the free Hopkinson pressure bar high-g loading technique, the pure cylindrical lead was mounted on the end section of the incident bar as a specimen to obtain the change law of the axial strain with the shape of acceleration pulses. Both the experimental tests without using pulse shaper and numerical simulations under sine-shaped acceleration pulses were performed and axial strain of the specimen was measured. Results revealed that the shape of acceleration pulse shows highly effect on the damage of the specimen. The axial strain of the specimen arises linearly with the increasing of the acceleration peaks whose durations are all 17μs; while, due to the complexity of plastic wave propagation, 135μs is a critical duration at which axial strain reaches to the maximum under the condition of different durations. The final axial strain of the specimen is determined by both the stress level and stress increment in every time step.

Abstract: 3D model and grid was conducted in Gambit,while single-phase flow field in the pump was simulated in CFD code-Fluent,by means of multiple reference frame (MRF) method, Renormalization group k-ε two-equation turbulence model (RNG k-εmodel) and Semi-Implicit Method for Pressure-Linked Equations (SIMPLEC) algorithm. Aim at problems generated by pump body such as body length limitation on pressure increasing, three new structure of labyrinth screw pumps,rotor separated LSP,stator separated LSP and rotor stator all separated LSP, were put forward in this paper.The analytical results got by contrasted pump hydraulic performance of different structure models indicated that pressure increasing magnitude and pressure increasing rate of the three separated pumps is larger compared to the unseparated pumps,and the conclusion was achieved that pump performance can be optimized through separating rotor or stator into sections by making ring slots on screw body.

Abstract: The mud pump damming technology is a new idea put forward for realization of mechanization and automation of warping dam construction. A mud pump damming machine is studied, the FEM of the mud transfer pump rotor is built, modal analysis and rotor-dynamic analysis are carried out, natural frequencies and mode shapes under different constraints are obtained and the critical speeds of the pump rotor are determined, which will provide reference to improve the running reliability of the mud transfer pump rotor.

Abstract: For the task of evaluating the inclusions in the steel specimen under high efficiency testing condition, it is important to make it clear that what testing sensitivity the ultrasonic method can reach for a specimen of large size, especially a thick one. In this paper, this problem is researched and discussed. Before experimental researching, we simulated the focused ultrasonic field formed in the steel specimen by DPSM (Distributed Point Source Method), the frequency ranges from 7.5MHz to 15MHz. DPSM analysis reveals that the ultrasonic field of certain strength can be formed in the thick steel specimen of coarse grain, and the focused transducer of 15MHz is suitable for the inclusion evaluation of thick steel specimens. Then, with the help of a precise micro-step C-scan equipment and the 15Mhz transducer (13mm Diameter, 255mm focal length), the ultrasonic test sensitivity research work was carried out on the thick steel specimen, by the way of testing the inclusions which's size were as tiny as possible, and located as far from the testing surface as possible, and at last, the ultrasonic detection results were testified by mechanical dissection. The dissected inclusions which can be tested are grouped into 8 different grades by its size, it is demonstrated that the deepest inclusion can be tested in the specimen is about 80mm beneath the testing surface by ultrasonic method, and reflection area is about 0.02mm², equivalent to a circle inclusion of diameter 0.16mm. In addition, there are some semi-quantitative relationships can be drawn among the grade of inclusion, the location depth of inclusion in the specimen, and the reflected ultrasonic signal strength from the inclusion, this give a way of evaluating the inclusion size in the thick steel specimen by the focused ultrasonic method.