Abstract: Nano-filler reinforced epoxy composites has been investigated in this study subjected to various mechanical and pin-on-disk tribological tests. Two different types of nano-filler were used namely, rigid nano-silica (SiO2) particles and soft nano-rubber particles. Incorporation of nano-filler in polymer matrix enhance mechanical properties. In addition, tribological response of composites are also better compared to neat epoxy polymer. However, the effect of nano-silica addition is much more pronounced than that of nano-rubber due to the high rigidity of nano-silica reinforced epoxy composite. This was mainly attributed to transfer film layer (TFL) formation. The TFL was further investigated by electron microscope and nanoindentor. The best set of tribological properties was achieved at 8 wt. % nano-silica addition. This was due to better reinforcement dispersion and continuous transfer film layer formation which eventually control the overall friction and wear mechanism.
Abstract: High quality (200) and (111) orientations cubic MgZnO thin films were made on (200) and (111) orientations MgO substrates separately under different condition with higher and lower migration energy of reactive atoms separately. The crystal quality of (111) orientation MgZnO thin film is higher than (200) one because of the stronger horizontal migration of atoms on (111) surface under high temperature condition, the surface of (200) orientation MgZnO thin film is smoother than (111) orientation one because of lower vertical growth speed of (200) MgZnO grains. The band gap of (111) orientation MgZnO thin film is smaller than (200) one because of more Zn atoms in (111) orientation MgZnO lattice than that in (200) ones. This paper gives an effective method to improve crystal quality of different orientation MgZnO thin film under different condition, which is meaningful in application of cubic MgZnO in different areas.
Abstract: This paper is dedicated to the issues of designing of outriggers for avoidance of vehicle tilting during its stability tests. An analysis of existing types of outriggers was done by authors as well as legislative requirements on them. The reliable and well-timed operation of outriggers largely depends on the height of their positioning on a vehicle. In order to determine this important parameter a special methodic of determining the tipping angle of the vehicle with the use of computer-aided design (CAD) was composed by authors. The article also contains some main principles of strength analysis of the structure a very important part of which became the necessity of determination of coefficient of friction between the outrigger sliders and the supporting surface. This coefficient has a direct impact on the value of transverse forces appearing at the ends of outrigger beams.
Abstract: In this paper, the axial magnetic field amplification characteristics of the trapezoid-shaped magnetic flux concentrator at micrometer scale are studied. The factors of the dimension parameters including the ratio of the outer and inner width, the aspect ratio, the air gap, as well as the material property including the relative permeability influencing on the magnetic gain are analyzed using the finite element method. It indicates that the concentrator with air gap shows obvious magnetic amplification. The concentrator shows intensive magnetic gain with the increasing ratio of the outer and inner width, aspect ratio and the decreasing air gap. When the dimension parameters of the length, the outer width, the inner width, and the air gap are of 1000um, 200um, 10um, and 5um respectively, the magnetic gain of 65 is obtained. Additionally, the magnetic gain increases with the relative permeability of the concentrator. When the relative permeability reaches a certain value, the magnetic gain tends to saturation. The magnetic flux concentrator has a linear working range of 12.8mT. The study can provide a theoretical reference for the design and application of the trapezoid-shaped magnetic flux concentrator.
Abstract: The increase of the quality in a productive process allows reduction of costs besides adding value to the product. When manufacturing a product within the tolerances specified in the design it is possible to obtain a correct operation of this product, ensuring the minimum time of use and with a lower risk of early failure. In this sense, machines and equipments involved in the manufacturing and inspection processes must also maintain an acceptable quality of operation by knowing the errors present in the machine structure through the calibration, such as errors due to lack of orthogonality between the axes, caused by inaccurate assemblies. The calibration errors in these machines allow elaborate error compensation plans and thus improve the rate of flawless products in production. The objective of this paper was to identify the influence of errors due to a lack of orthogonality in a bridge type coordinate measuring machine (CMM) through calibration and mathematical modeling of errors. Error calibration is performed with a linear displacement transducer, a granite square and a set support brackets for the granite square. By means of the calibration data and the mathematical modeling of the orthogonality deviation an influence of the measured deviation on the "X" and "Y" directions of the CMM is obtained. The error due to the lack of orthogonality between the "X" and "Y" axes of the CMM was approximately 8.9558 negative arcoseg; in this way, it is evidenced that the angle formed between these axes is 89.9975°. Through this study it can be concluded that orthogonality deviation in the main plane of the machine produces negative components for the axes "X" and "Y", with higher influence on the points collected as it away from machine scales, making greater the error intensity on the results of measurements made at positions farthest from the "X" and "Y" scales.
Abstract: This paper describes a multiphase computational fluid dynamics (CFD) based numerical study about aeroacoustics response of NACA0012 airfoil for both normal and icing conditions. Three different turbulence models (RANS, DES & LES) are tested where Detached Eddy simulation (DES) turbulence modelling approach is found suitable for this case study. Aeroacoustics numerical results for clean NACA 0012 are compared with the experimental data obtained from NASA report 1218 , where a good agreement is found. An extended CFD study is carried out for iced NACA 0012 airfoil, where results show more boundary layer flow separation in case of iced blade profile that leads to a change in the aerodynamic characteristics of the blade profile and increase in sound level for iced airfoil as compared to the clean NACA0012 airfoil.
Abstract: This paper describes a case study of wind resource assessment in cold climate region. One-year SCADA data from a wind park has been used to make a comparison with the Computational Fluid Dynamics (CFD) based numerical simulations of wind resource assessment and Annual Energy Production (AEP). To better understand the wind turbine wake flow effects on the energy production, ‘Jessen wake model ‘is used for the numerical simulations. Results show wind resource maps at different elevations, where wind turbine wake flow effects the wind turbine performance and resultant power production. CFD simulations provided a good insight of the flow behavior across each wind turbine, which helped to better understand the wind turbine wake flow effects on wind turbine performance and annual energy production. A good agreement is found between numerical simulations and field SCADA data analysis in this study.
Abstract: The bearings are widely used in the rotating machinery systems to support the mechanical, structural for system. In a high rotating speed, the spindle to be stable rotating is dependent on a high performance bearing. Therefore, the dynamic characteristic of a ball bearing is very importance and need to study. In this work, the dynamic characteristic of a ball bearing is focused to study. Because the geometric of ball bearing are so complex, the finite element analysis is employed to investigate. By using the finite element analysis software ANSYS, the bearings meshed model can be setup. The dynamic properties, natural frequency and mode shape of ball and global system, can be studied to improve the high spindle rotating stable performance. Numerical indicates that the stress, strain and dynamics of the ball bearing system can be investigated in this finite element model.
Abstract: In order to improve the vibratory roller ride comfort, a multi-objective optimization method based on the improved genetic algorithm NSGA-II is proposed to optimize the design parameters of cab’s isolation system when vehicle operates under the different conditions. To achieve this goal, 3D nonlinear dynamic model of a single drum vibratory roller was developed based on the analysis of the interaction between vibratory roller and soil. The weighted r.m.s acceleration responses of the vertical driver’s seat, pitch and roll angle of the cab are chosen as the objective functions. The optimal design parameters of cab’s isolation system are indentified based on a combination of the vehicle nonlinear dynamic model of Matlab/Simulink and the NSGA - II genetic algorithm method. The results indicate that three objective function values are reduced significantly to improve vehicle ride comfort.
Abstract: Various studies are being conducted on the application of DBD (Dielectric barrier discharges). The internal dielectric has a very important characteristic on DBD, thus we analyze of the characteristics on dielectric barrier discharges depending on the relative permittivity and frequency. Through simulation, the discharge voltage was calculated based on relative permittivity and frequency of real used dielectrics (Green sheet, Down dielectric, white dielectric). We investigate that increased relative permittivity and fast frequency occur the decrease of the firing voltage. Also, we investigate the frequency dependence of the dielectric constant and dielectric loss of dielectric layers measured at a frequency region of 100Hz to 10MHz. In a condition of drive within 1MHz, with regard to the change of real and imaginary part according to frequency, it has quite stable dielectric constant in the condition of drive within 1MHz.