Applied Mechanics and Materials Vol. 607

Abstract: An emulsion of biodiesel and water is one of the possible approaches that have been used to overcome diesel engine pollution. In this work, the performance and emission characteristics of a 4-cylinder diesel engine using pure diesel, biodiesel B20 and emulsified biodiesel were investigated. Emulsified biodiesel containing 5 % and 10 % water were utilize for the engine tests. During the experimental work, the engine was set-up at 2500 rpm and 20 % to 60 % loads. The result shows the reduction in NOx formation when the water content in emulsified biodiesel increased from 5 % to 10%. For the performance, there were no significant differences between the engine break powers measured for emulsified biodiesel containing 5% water and diesel fuel.

Abstract: Hydrostatic guideway is widely used in heavy and ultra-precision machine tools due to their high bearing capacity, low coefficient of friction and high capacity of precision-remaining. So it is necessary to carry on theoretical research on its dynamic characteristics. Firstly, the oil-film damping coefficient of closed hydrostatic guideway throttled by capillary is derived. Secondly, a new dynamic mathematical model, considering the oil damping effect, the extrusion effect and the volume effect, of the closed hydrostatic guideway is proposed. Thirdly, the frequency characteristics and step characteristics of it are simulated in Matlab Simulink through the transfer function. Finally, the paper investigates the influence of damping coefficient, the oil pressure, volume effect and the initial oil-film thickness on the dynamic characteristics of closed hydrostatic guideway throttled by capillary.

Abstract: This paper investigates the dynamic characteristics of the aerostatic journal bearing, the rotation center of which is not the center of the journal length. The Finite Difference Method (FDM) and the perturbation method are employed to calculate the stiffness and damping coefficients. Results show that the coupled stiffness and damping coefficients cannot be neglected due to the rotation center being not the center of the journal length. Furthermore, with the increase of the distance between the rotation center and the center of the journal length, the coupled stiffness and damping coefficients increase.

Abstract: Considering the influence of wheel vertical load transfer and Steering angle, the paper establishes a dynamic model of 7 degrees freedom for vehicle under Braking in Turn Condition. Based on this model, wheel lock braking and ABS braking were researched and simulated. The simulation results show directly that first lock of front wheel loses vehicle steering performance, first lock the rear wheel sideslips, ABS braking can prevent loss of vehicle steering performance and sideslip, but slightly long braking distance.

Abstract: The water-lubricated bearings have gained an increasing focus to overcome the disadvantages of the oil film bearings and gas bearings. In this paper, the influences of orifice diameter in aligned and misaligned conditions on the static performance of two hydrostatic, four-recess, water-lubricated journal bearings used to support a rigid rotor, are investigated. The steady Reynolds equation for the journal bearing for the turbulent bulk flow and the film thickness expression considering tilting angles are used and numerically solved by finite difference method. Results demonstrate that the static performances, such as the quality, power loss and temperature rise are affected by the tilting angles, orifice diameter to some degree.

Abstract: Fine blanking is a press-working process that permits the production of precise, finished components which are cleanly sheared through the whole cutting surface. The manufacturing cost can be reduced because the secondary operations such as milling and broaching can be eliminated and the multistage combined stamping process can be added. The product cost can increase, however, while the precise fine blanking tool and high cost fine blanking press are required. Therefore it is important to design the fine blanking tool in view of the life expectancy of the punch. In this paper the fatigue simulation of fine blanking tool punch for automobile start motor flange was conducted using the commercial FEA software ANSYS. Initially, the material properties were tested and the fine blanking tool was designed for production experiments. The modelling of tool elements and the fatigue simulation according to repeated loads were conducted. As a result of fatigue simulation, the fine blanking tool punch for start motor flange had been fractured with 3,981 strokes. In the fine blanking production experiments, the fine blanking tool punch had to be regrinded after it was used with 3,425 strokes. It was also found that the fatigue simulation of fine blanking tool punch was conducted with an error of 14%.

Abstract: After a study on the existing preheating scheme of vehicle engines, we propose to design an onboard electromagnetic preheating unit. Connected to 220v power, the unit may generate a high frequency alternating magnetic field through rectification and inversion. It will heat the engine cover directly and constantly to conduct heat to the engine and its oil so that the temperature rises up to meet the conditions for vehicles to start up.

Abstract: Stringent emissions regulations and increasing concern on greenhouse emissions are challenging the researcher to find the alternative fuels like biomass and biodiesel. However, the main issue biodiesel fuel (BDF) from waste cooking oil (WCO) is high toxic emission of Nitrogen Oxides (NOx) and particulate matter (PM) in burning process of burner combustion. Thus, the emulsification concept of BDF and water mixing were studied with focusing in controlling of combustion process especially during early stage combustion in order to minimize the harmful emission. This main purpose of this research is to investigate the effects of biodiesel fuel from waste cooking oil on mixture formation and emission in burner system. The mixture formation behavior of BDF-water-air premixing was investigated due to this spray characteristics will contribute in combustion process that predominantly influence to the NOx and PM emission production. Blending of biodiesel ratio was varied from 5vol%(WCO5)-15vol%(WCO15). Water content under emulsified biodiesel was varied up to 15 percent, and equivalence ratio from 0.6 to 2.0. The real spray image of emulsified WCO fuel and different equivalence ratio were captured by optical visualization system together with color digital camera. The images of the spatial distribution of WCO fuel-water-air mixing will be further analyzed compared with the exhaust emission production in order to understand the influences of mixture formation on combustion process and burning process. Increased of water content, promoted fuel-air premixing and spray tip penetration thus predominantly influences to the reduction the exhaust emissions.

Abstract: Abstract. Currently, traffic law enforcement agencies rely mainly on the license plate to identify illegal vehicles. But for those vehicles with no license plates or license plates are obscured or slipped, the existing techniques do not work. In this paper, a method to reconstruct the external dimensions of vehicles from 2D images is therefore proposed to identify those illegal vehicles above. The external characteristics of vehicles and methods to model vehicles are analyzed. Based on the analysis, we simplified vehicles as a combination of a rectangular parallelepiped and trapezoidal polyhedron which can be produced with corner points from 2D images. The process to establish the vehicle model with corner points is studied. Finally with Visual C++ and SolidWorks API, the 3D model of a vehicle is established based on a 2D image. The vehicle's primary outlines information including length, width and height are restored, and the information can be used to identify the vehicle.

Abstract: Taking into account China's abundant coal resources, methanol and DME(Dimethyl Ether) obtained from coal are good alternative fuels. The research project is to utilize the fuel of DME and methanol in diesel engines for new combustion models PCCI (Premixed Charge Compression Ignition).The tests of the PCCI mode with different boundary conditions were studied on PCCI test bench. PCCI combustion is consisted of three stages: low temperature reaction of DME, high-temperature reaction of DME and diffusion combustion reaction of methanol. DME as combustion improver should be kept relatively low concentration, and with the decrease of methanol, its concentration need to be reduced. Methanol and formaldehyde are important parts of HC emission, their volume fraction was about 70%.