Applied Mechanics and Materials Vol. 248

Abstract: Micro-arc oxidation (MAO) coatings were synthesized on MB3 magnesium alloy substrate. Two different electrolyte (Ⅰ) and electrolyte (Ⅱ) were adopted, and the performance of ceramic coatings was compared. The morphology feature, phase composition, and chemical composition of the formed coatings were studied by metallographic microscope, scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), XRD, respectively. The corrosion resistance of the coatings was evaluated by salt spray test. The research results show that, the starting and terminal voltage are different during the oxidation process, they are 220V and 375V in the electrolyte (Ⅰ), and 150V and 270 V in electrolyte (Ⅱ). After MAO, The sample surface in electrolyte (Ⅰ) is light gray, and looks tender and smooth. The ceramic coatings obtained in electrolyte (Ⅱ) are relative rough and white in colour. But MAO coatings obtained in electrolyte (Ⅱ) has higher deposition rate. Salt spray test show the corrosion resistance of samples obtained in electrolyte (Ⅱ) are better than those in electrolyte (Ⅰ), which is related to the thickness of the MAO coatings.

Abstract: Diffusion bonding between the Cu-10%Fe and Al6061 alloys were successfully achieved at various temperatures (450-525°C) in the argon atmosphere. The bonding interface regions were analyzed using scanning electron microscopy and energy dispersive spectrometry and XRD. The presence of Fe particles in Cu was found to have an influence on the kinetics of intermetallic compound layer formation. Cu-Fe/Al 6061 exhibited the slower growth rate of intermetallic layers than Cu/Al 6061 after diffusion bonding. The movement of Cu-Fe/Cu9Al4 interface into Cu-Fe substrate appears to be hindered by the presence of populated Fe-containing particles and filaments. In addition to Cu9Al4, CuAl and CuAl2 intermetallic layers, Al7Cu2Fe and unreacted Fe were observed to be present in the intermetallic layers. The intermetallic layers which are close to Cu such as Cu9Al4 and CuAl were observed to be harder in Cu-10%Fe/Al 6061 than in Cu/Al 6061, suggesting Fe and its intermetallics have some strengthening effect on Cu9Al4 and CuAl.

Abstract: In order to know the static stiffness characteristics of the vehicle body in white, the bending stiffness and torsional stiffness of an automotive body in white were tested on a test bench of the static stiffness of an automotive BIW. The bending stiffness and bending deformation of the bottom of the BIW were determined. Also, the torsional stiffness and torsional deformation of the bottom of the BIW were obtained. The fitting curves and equations between loading torque and torsional angle were acquired at clockwise and counterclockwise loading, respectively.

Abstract: In order to determine the fatigue limits of two kinds of titanium alloy joint pipes connected by welding and rolling, the fatigue tests were carried out by test standard which defines the test method and failure rule. One cantilever-beam specimen was fixed on the shaker by the special fixture. The laser-displacement-sensor was fixed at the free end of pipe and the strain-gauge was adhesive at the root of the pipe. The first frequency of specimen was measured by these sensors. The first resonance frequency fell rapidly with the increment of the excitation loads of the shaker. The failure rule (1% drop of resonance frequency) of the standard was not same with the fatigue limit test of these connected pipes at the test beginning. In order to define the lives of two kinds of pipes, the stair method of sweep test was used to eliminate the effect of connection gap. Then the vibration fatigue of every specimen was tested at the last resonance frequency. And all the fatigue tests were finished using the failure rule which defines 1% drop of the steady resonance frequency.

Abstract: In the conventional Reverse Engineering (RE), the first step is modeling industrial components from point cloud to parametric CAD model, and then the necessary design will be operated in a parametric CAD environment. Therefore the reverse engineering process is very time-consuming and error-prone. The Anatomical CAD means allowing the common Computer Aided Design operations on 3D anatomical data. 3-matic is a software package which equipped with an Anatomical Reverse Engineering module, with this module we can do the design operations on anatomical data. In this paper, we propose a new design methodology integrated with Anatomical CAD, which we can eliminate the first step of reverse engineering of the scanned data to a CAD format, save the time and work more accurately.

Abstract: The semi-hermetic reciprocating compressor is the dominant noise source of food refrigeration unit. Excessive noise and vibration have a negative impact on both people's health and work efficiency；moreover, it causes fatigue damage to machinery thus reducing its working life. In this paper, numerical simulation of noise radiation from semi-hermetic reciprocating food refrigeration was carried out by successful combination of Pro/E, Hypermesh, Nastran and Virtual Lab Acoustics software. The simulation results show that the low-frequency noise radiation near the end of the piston-cylinder is directional and stronger than that of the other side, which offers a valuable reference for noise reduction. In addition, the sound pressure dB curve of any field point can be obtained through the numerical simulation, and it clearly shows that sound pressure values away from the piston end are significantly lower than those at the piston side; and noise radiation energy of compressor concentrates at 500Hz and 1000Hz. This paper provides an effective research method for the semi-hermetic reciprocating compressor’s noise reduction

Abstract: Fast Elitist Non-dominated Sorting Genetic Algorithm is introduced in this paper to optimize the performance of double helical gears with high contact ratio.It is effective and timesaving. Numerical examples that illustrate the developed theory are provided. Feasibility of it is validated by analysis of contrast between Pareto optimal solutions and original data.

Abstract: The over-head transmission lines will gallop because of the natural conditions, which will cause serious incidents. In order to avoid the galloping of the over-head transmission and improve the effect of transmission system, some analyses are done about the formation mechanism of transmission lines galloping and the current anti-galloping devices. On the basis of the reactive mechanism of swing, the active anti-galloping mechanism is presented. Besides, the mathematical model of the anti-galloping system is raised. With the theoretical calculation and numerical simulation for the conductor which is equipped with active anti-galloping device, the result is feasible. The paper introduces the structure of active anti-galloping, which lays the theoretical and practical basis on the realization of anti-galloping.

Abstract: A coupled vibration model of a stiffened cylindrical shell with a stiffened interior plate is established based on the receptance method to get the stiffeners' influence on the plate-shell coupled structure's vibration characteristics. Numerical analysis on how an increase of the plate's and the shell's stiffener number affect the combination's vibration is carried out. It shows that the amplitudes of both the plate's and the shell's acceleration levels would reduce and peaks of their vibration curves would shift to the higher frequency range as stiffeners on the plate increases. And increase of the shell's stiffener number has little impact on the plate's acceleration level curve except for some peaks, but it would reduce the shell's acceleration level.

Abstract: This paper is devoted to numerical research on coupling between elastic spherical shell and the coated viscoelastic layer as well as the scattering of incident plane wave by the double-layer spherical shell. The scattering sound field is solved based on impedance boundary condition by boundary element method (BEM). Dynamic finite element method (FEM) is used to numerically simulate the acoustic impedance boundary condition which involved in the coupled spherical shell. Impedance distribution for elastic spherical shell and elastic spherical shell coated viscoelastic layer is calculated and its effect on the target strength (TS) is discussed finally.