Applied Mechanics and Materials Vols. 433-435

Abstract: Machining performance is often limited by chatter vibration at the tool-workpiece interface. Chatter is a type of machining self-excited vibration which originates from the variation in cutting forces and the flexibility of the machine tool structure. Machining chatter is an inherently nonlinear phenomenon that is affected by many parameters such as cutting conditions, tool geometry, cutting speed, feed rate, depth of cut, overhang length of tool, clamping condition of workpiece. This study presents experimental approach for investigation of effects of various cutting tool geometry on the onset of chatter. In turning process, measured cutting force signal and triaxial accelerometer signal was used to know the characteristics of chatter vibration. The static and dynamic component of cutting forces reflect onset of chatter vibration. Proper selection of tooling is an important parameter in terms of chatter elimination in machining.

Abstract: This article mainly addresses the technology of improving heat dissipation performance of power battery packs using Phase Change Material (PCM). This new technology aims to reduce the temperature gradient among the battery packs. As the thermal properties of the pure paraffin wax are hard to meet the dissipation demand, changes are made to add graphite particles into it. Commercial CFD software ANSYS FLUENT is used to simulate the heat dissipation process during battery discharge using PCM and traditional forced air cooling methods. The simulation results show that both under constant current and pulse current the maximal temperature and temperature gradient by the end of discharging using PCM method are relatively lower than that of using forced air cooling method.

Abstract: Machine vision based surface roughness inspection method is applied to assess different cylindrical grinding surfaces under LED illumination. Images directly recorded by a camera are analyzed by gray level co-occurrence matrix (GLCM) method to discover its texture information. It shows obviously relationship between feature values of the matrix and their corresponding surface roughness values. Uniform table are also designed to choose optimal parameters, which is five of distance between pixel pairs and ninety degree of angle to calculate GLCM. Entropy is chosen to represent different surface roughness images by comparison of correlation coefficients between the parameters and the corresponding surface roughness values.

Abstract: Developed the pneumatic press machine with a controllable precision stroke through this study. Conventional pneumatic presses cylinder installed in the vertical direction to deliver the power, but in contrast to conventional approaches, it is applied a horizontal cylinder by installing a pressure sloping portion, so that the cylinder power delivers to the vertical direction. This reduces the height of the press, transmitting the power of the cylinder controlling the straight length of the piston by moving regulator so the stroke of the press can be precisely controlled. In addition, in the press manufacturing by changing a driving cycle for the safety of workers and the working environment is improved.

Abstract: Press Pack IGBTs modules have the characteristics of easy series connection and double side cooling widely used in industry, electric power, smart grid and other fields. Press Pack FRD (Fast Recovery Diode) chips is a component of Press Pack IGBTs module. In the actual operating conditions, the electrical parameters of FRD device will change in the electrical properties under pressure-stress, especially the Forward Voltage (VF) parameters. This change of the VF parameters will have adverse effect on the reliability of FRD chip and the overall module. In this paper, according to the stress of physical model of semiconductor material silicon were analyzed, proposed method to stress effect on the VF parameter of the FRD simulation analysis software.

Abstract: Piezoelectric materials can convert between electric and stress and has been applied widely in industrial field. Lead strontium zirconate titanate (PSZT) ceramic, as one kind of piezoelectric material, shows good piezoelectric properties and has been used in making resonators, sensors etc. For further improving its piezoelectric properties, various elements have been doped into PSZT. In this paper, two kinds of oxides, MnO₂ and CeO₂, are doped into PSZT. The electrical properties of the doped PSZT samples are tested and the microstructures of samples are observed as well. Results show that, after doping 0.1wt% MnO₂ and 0.1wt% CeO₂, the electrical properties are enhanced to: d₃₃=569pC/N, tgδ=0.94%, kp=0.632, ε=2882. It can also be found from SEM results that, as increasing the doping amount of MnO₂, the grain size of samples increases, and by doping CeO₂, results show reverse effect.

Abstract: Shape memory alloy (SMA) is a type of smart material with huge driving force, and large driven displacement. Using SMA as the structure driver may force a bi-directional deformation structure that can achieve high efficiency and compact driving structure. SMA, together with elastic component, forms the two-way driving structure; however the two, if respectively serving as the driver, can enable the occurrence of the simplest bi-directional drivable structure. The offset structure constituted by SMA, not only can achieve two-way drive, and does not require continuous input of energy during the shape-stabilizing period. This paper studies the design methods of these two structures, gives the typical formulas, which makes possible efficient and compact bi-directional drivable structures.

Abstract: A report about the current industry standards of technological, economic and legal development for the recycling and reuse of civil construction waste (CCW). The use of CCW, such as recycled aggregate inserted into concrete, is still in its initial stages in Brazil [. This paper's main objective was to evaluate the quality of concrete produced using different amounts, or fractions, of recycled concrete aggregate RCA from the residues of demolition wastes RDW from UFRJ's university hospital, located at its Rio de Janeiro campus. These residues had the dimensions of crushed gravel, and were inserted into a mix of conventional concrete for making interlocking concrete paving, based on the characterization of the recycled aggregates and mechanical tests, carried out on laboratory produced cylindrical specimens of concrete, contributing to the increase in the recycling of cement and concrete in Brazil.

Abstract: Heat exchanger, which is to transfer the heat from the fluid with high temperature to the equipment with relatively low temperature.There are at least two kinds of fluid participate the process of transferring heat, the fluid with high temperature is called hot-fluid,release heat, and the one with low temperature is called cold-fluid absorb heat. Heat exchanger is a very necessary and important part in many areas and its investment always compose 30~40 percent of the whole investment. Moreover according to the policy of the government Energy development and conservation,the energy saving in the first place, the use of heat exchanger has a very close relationship with the development of energy and save of energy. In this paper we describe the thermal design of surface type heat exchanger with practical example.

Abstract: In this paper, the purpose and content, implement project and test of reconstructing of the centrifuge have been introduced. The main idea of reconstruction is that on the condition of reserving driving electromotor, main transmission system, supporting system and arm of centrifuge, timing system, monitoring system and assistant transmission system have been replaced, and the synchronization measure weight system is supplied to measure the centroid of the arm of centrifuge, in the meantime, the oil is supplied to the nacelle of centrifuge in order to make the centrifuge have the ability of complex test. In the result of aborative design, the centrifuge has higher level and ability of environment test after the reconstruction.