Advanced Materials Research Vol. 684

Abstract: Al-Cu alloy and its matrix composites reinforced with different volume fractions of short carbon fibers covered by copper have been produced by powder metallurgy method and heat treatment. The effects of the fiber volume fraction and load applied on the wear and friction behaviors of the composites were investigated. The results showed that the Cf/Al-Cu composites had better mechanical and tribological properties compared to Al-Cu alloy. The applied load did not obviously affect the wear resistance and friction coefficient.

Abstract: . In order to obtain suitable titanium mesh MEA (membrane electrode assembly) for direct methanol fuel cell (DMFC) molding temperature conditions, titanium mesh was used as electrode substrate material, Nafion 117 membrane was used as proton exchange membrane, PtRu/XC-72R and Pt/XC-72R were used as anode catalyst and cathode catalyst respectively, anode and cathode of titanium mesh MEA were prepared by drop-coating method. When the MEAs were molded by hot-pressing under 5 MPa for 180 s with different temperatures of 115°C, 135°C and 155°C, respectively, the maximum power density of Ti mesh-based MEAs increases firstly, after the first peak, it gradually decreases along with the increase of molding pressure conditions, and the maximum power density appears at the molding temperature of 135°C, so conclude that molding temperature of 135°C is more appropriate for making the titanium mesh MEA.

Abstract: In this paper, the behavior of ejected jet is studied at three different substrates (conductive, semiconductor and dielectric) in continuous electrohydrodynamic inkjet printing mode. Because the polarization charges will accumulate at the surface of the substrate in a short nozzle-to-collector distance, one can observe that the different flight behavior in the space. Results show that the substrate has little effect on the threshold voltage and the relaxation time of the substrate can be used to indicate the behavior of the jet. When the lifetime of the jet is larger than the relaxation time of the substrate, the jet can be deposited on the substrate regularly. Based on this guideline, a designed parallel lines and grid pattern are fabricated with several micrometers on a silicon substrate. These show that the designed pattern could be fabricated in a controllable jet. In the future, this method is able to be utilized to fabricate the mirco/nano-devices.

Abstract: Without initial imperfection and damage evolution model, it is difficult to analyze the necking behavior by finite element analysis with continuum theory. Moreover, the results are greatly dependent on the size of the initial imperfection. In order to predict necking phenomenon without geometric imperfection, in this study, a crystal plasticity model was introduced in the 3-dimensional finite element analysis of tensile test. Grains were modeled by an octahedron and different orientations were allocated to each grain. Damage model was also used to predict the sudden drop of load carrying capacity after necking and to reflect the void nucleation and growth on the severely deformed region. Well-known Cockcroft-Latham damage model was used. Void nucleation, growth and coalescence behavior during necking were predicted reasonably.

Abstract: The paper presents the researches to determine the best technologies to improve the lifetime of the corner welding. Generally it is says that the convex corner welding presents high mechanical properties because of the greater area section. The practice activity shows that in fact, because of the stress concentrators, these shapes of the welding are not the best solution. A better shape of the corner welding is the concave one that provides better results in the working conditions. To provide better results of the convex shape corner welding different recondition techniques are known. The paper is focused on fatigue testing performed on different samples realized with different beads on different working parameters. There are studied different reconditioned probes and the results are reported in fatigue curves.

Abstract: In this paper, a novel method to recognize gear fault pattern was approached based on multi-scale morphological undecimated wavelet decomposition, sample entropy and grey incidence. Firstly, multi-scale morphological undecimated wavelet decomposition was developed based on the characteristic of impulse feature extraction in difference morphological filter. And it was used to process different gear fault signals in five levels. Secondly, the sample entropy of each level was calculated. Finally, the sample entropy was served as the feature vectors and the grey incidence of different gear vibration signals was calculated to identify the fault pattern and condition. Practical example shows the efficiency of the proposed recognition method. It is suitable for on-line monitoring and fault diagnosis of gear.

Abstract: In this paper, a novel comprehensive fault identification approach was proposed based on the harmonic window decomposition (HWD) frequency band energy extraction and grey relation degree. Firstly, in order to eliminate the influence of noises, the line structure element was selected for morphological filter to denoise the original signal. Secondly, due to the energy of vibration signal will change in different frequency bands when fault occurs, therefore, the six feature frequency bands which contain the typical fault information were extracted by harmonic window decomposition that need not decomposition; and the energy distribution of each band could be calculated. Finally, these energy distributions could serve as the feature vectors, the grey relation degree of different vibration signals was calculated to identify the fault pattern and condition. Practical results show that this method can identify rotor fault patterns effectively.

Abstract: This study presents a novel estimation method of sample properties in dynamic mode Atomic Force Microscope (AFM). A cantilever mock system without the interaction with sample is used to generate a reference trajectory for deflection and the control synthesis problem is posed in a robust optimal control and multi-objective LMI framework. This design assumes the nonlinear tip-sample interaction force as a disturbance and estimates it through disturbance rejection technique. The sample topography and properties can be obtained by interpreting the estimated tip-sample interaction force and applying tip-sample interaction models.

Abstract: The fuel system experimental platform based on Stewart manipulator is used to test the performance and reliability of airplane’s fuel system. Synthesizing efficiency and safety, direct drive method is used as actuator of the experimental platform. Kinematic and dynamic model of the parallel manipulator platform is established. Servo motor and hydraulic cylinder of pump control are modeled for deducing the mathematical model of the experimental platform. Simulation results of the experimental platform show the platform of direct drive method can satisfy the requirements of operation. In addition, data from the simulation can be used as the basis for the design and optimization of the experimental platform for fuel system.

Abstract: Introduce data extract from old Rolling processing measurement and control instrument. Research data transmission between administrative area and production field; achieve record, save, monitor and output of machine data. Research the relationship of administrative area and production field. Study control platform on PC, achieve the control of machine and operator by PC.