Applied Mechanics and Materials Vols. 568-570

Abstract: Oil pipelines usually pass through suburbs areas and urban areas. When the pipeline occupy some private properties, the compensation to private properties owners is necessary. In fact, the oil pipe arrangement is very complicated when the unit cost in suburbs and urban areas is different. Hence the oil pipe arrangement scheme with compensation conditions is proposed to study the complicated problem. The model shows that compensation cost can affect the pipeline arrangement very sensitively. The model can obtain the optimal scheme to construct oil pipe when given different compensation cost.

Abstract: This study reported the statistical optimization based on Taguchi designed experiments to improve the tensile properties of 6061 Aluminum alloy by the friction stir welding (FSW) experiments. The morphology and the structure of the friction stir welded experiments were characterized by scanning electron microscopy. Based on analysis of variance, the impacts of control factors have been identified for the tensile strength of 6061 aluminum alloy by friction stir welding. Experimental results revealed that the defect free butt joints could be obtained by cylindrical-screw type of tool shoulder and the joints made with a cylindrical-screw type resulted in better tensile properties compared to the other two shoulder geometries. Furthermore, it was clear that the tensile properties are greatly improved by friction stir welded experiments in the Taguchi design, and these findings have achieved the desired values in regard to the friction stir welded Experiments. The proposed procedure was applied at friction stir welded experiments, and the implementation results demonstrated its feasibility and effectiveness to enhance the tensile properties by FSW .

Abstract: To solve the problem of underground tunneling face from the empty top, using FLAC3D analysis software, surrounding rock stability for coal roadway 2-1121 of Ganhe Coal Mine are analyzed in numerical calculation. (1) During the tunneling, distance drivage face head-on 0.5-1m at the roof of roadway deformation and destruction features are more obvious, the two sides of roadway are even more significant. (2) Ganhe Coal Mine roof deformation has been established with different empty the experience formula of the zenith distance, obtained Ganhe underground tunneling face reasonable empty zenith distance is 3.5m. (3) Temporary support can obviously reduce roof deformation, reduce thickness of plastic zone of the top, to improve the stability of surrounding rock tunneling faces.

Abstract: To modify a diesel engine into a natural gas engine, the supplying system, intake system, ignition system, combustion system and post-processing system are redesigned to meet the requirements of applying natural gas on the engine. Then on the basis of calibration of basic ignition advance angle and volumetric efficiency of natural gas engine, bench test is done to study the velocity performance, load performance and universal performance, as well as a comprehensively evaluation on the performance of natural gas engine. The result indicates that the modifying of nature gas engine is reasonable as it achieves the application of CNG on the engine and a comprehensive performance of engine.

Abstract: This paper introduces the elements, production, development, strongpoints and application of electromagnetic riveting. It analyses the effect of different length of rivet on the connection. The transmutation of rivet is well proportioned. As the length increases, the symmetry of rivet decreases. This paper compares pneumatic riveting and electromagnetic riveting, and expatiate the strongpoints of electromagnetic riveting, such as one time forming, easy to control, symmetrical transmutation, low undulation, steady connecting quality, easy to rivet. Finally, this paper summaries the electromagnetic riveting technology and calls attention to it.

Abstract: Thermal Cycle is a common test to ensure solder joints and interconnects reliability of astronautic electronic products through eliminating infant failures caused by latent defects. Both over-testing and under-testing risks have to be considered sufficiently during the constituting of thermal cyclic test scheme. Consequently, the methodology presented in this paper offers a novel way to evaluate these risks. Safety analysis on the thermal cyclic test scheme can prevent unnecessary operating life consumption, while the effectiveness analysis can ensure the sufficiency of the test and get rid of the defective products. Additionally, 3 thermal cyclic test schemes which can be applied on a signal acquisition board were analyzed with this methodology individually, and the most felicitous test scheme was identified at the end of this procedure.

Abstract: In the present paper, the incipient cavitations number was analyzed by theoretical considerations. By using simulation methods, it could be regarded that the incipient cavitations number was mainly dominated by the contraction ratio of the orifice plate. The less the contraction ratio of the orifice plate is, the larger is the incipient cavitations number. The effects of orifice plate’ thickness on the incipient cavitations number was not obviously and could be neglected. When Reynolds number is more than 10⁵, Reynolds number has little impact on the incipient cavitations number.

Abstract: Fan blades noise is mechanical noise and aerodynamic noise, and the aerodynamic noise is the main noise. Fan's speed, blade number, angle, radius of curvature is the main factor affecting the fan blades noise. Key of control fan noise, should be placed in fan design, Reduce the circumferential velocity, leaned blade, increase the radius of curvature is favorable measures of reducing the noise of the fan blade. Control of noise from the source, will achieve better results.

Abstract: The model of ultrasonic propagation through contact interface, which is an important factor in the ultrasonic transducer used in wire bond, was established by Hertz contact theory. From the Hertz contact theory, it is found that higher order harmonic wave and waveform distortion occur when the ultrasonic wave propagate through a contact interface between two isotropic solids pressed together. Based on the model, the effect of the contact interface between horn and capillary in wire bond transducer are tested by Laser Doppler vibrometer. The experiment results show that when contact interface pressure is in the range of 6 kPa to 10 kPa, higher harmonic wave and nonlinear coefficient is minimum. When contact interface pressure is more than 10 kPa, the nonlinear coefficient increases and bonding strength decreases as increasing of the interface pressure.

Abstract: The test method for C1 tire snow grip performance based on European ECE R117 is analyzed; the test and evaluation process and test ability for C1 tire snow grip performance has already been established. The feasibility research of the implementation of C1 tire snow grip performance has been done, which provides the necessary technical reserve for products performance development of domestic tire enterprises, drawing test and evaluation standards, tire performance matching and EU certification.