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Li P.,Henan Polytechnic University | Ouyang W.-Q.,DongFeng Commercial Vehicle Co. | Ma C.-Q.,China Institute of Technology
Zhuzao/Foundry | Year: 2014

The blowhole problem of end cover die casting is very outstanding during the trial production with a casting per mould. Blowhole formation cause is analyzed by means of InteCAST software, and then the modified project with two castings per mould was designed. Through simulation calculation on the original project and modified project, the result shows that for the original project, molten iron presents uneven filling, the outside of die castings fills obviously faster than the inside, air entrapment phenomenon exists in blowhole formation position; Whereas for the modified proj ect, liquid alloy filling mould is stable and even, overflow is designed at the last filling location and takes a good effect on eliminating gas and slag. Blowhole defect in cover castings has been effectively controlled by applying modified project during mass production.

Hu L.,Wuhan University of Science and Technology | Tang Z.,Wuhan University of Science and Technology | Xu X.,DongFeng Commercial Vehicle Co. | Yang Q.,Wuhan University of Science and Technology
Zhongguo Jixie Gongcheng/China Mechanical Engineering | Year: 2015

The principle of steady-state energy flow method to measure the damping loss factor was derived. Through this method, a certain type of particle damper damping loss factor was carried on the experimental study. The vibration simulation of steel plate which was pasted with particle damper was compared with experimental research. The experimental results of the steady-state energy flow method show that, the particle damper damping loss factors vary with the changes of acceleration and present the obvious “piecewise representation” features. At the same time, the damping loss factors vary with the changes of the frequency and present the obvious “ridge” features. The reasons of these features were analyzed in theory. ©, 2015, China Mechanical Engineering Magazine Office. All right reserved.

Li P.,Henan Polytechnic University | Peng X.,Henan Polytechnic University | Su L.,Henan Polytechnic University | Ouyang W.,DongFeng Commercial Vehicle Co. | Niu J.,Henan Polytechnic University
Engineering Review | Year: 2016

Grey iron flywheels were often found to have been fractured during shakeout, surface cleaning, finishing, packing, dynamic balance measuring and so on. Among them, a failed flywheel was subjected to forensic failure analysis by visual inspection, chemical composition analysis, scanning electron microscopy, microstructure analysis, hardness measurements, etc. The results show that the internal crack was initiated near the centre of the flywheel and propagated toward its outer edge. Some inclusions containing Si, S, and Ca resulted in the fracture of the flywheel. The graphite plate length in the vicinity of the crack zone is longer than the range specified, and its ferrite content exceeds the one in the material as a whole. The average hardness near the crack zone is lower than the lowest limit of HB187-250 (the relevant material standard). The causes for the formation of the inclusions have been discussed and some measures such as: controlling the temperature of the molten iron, applying a ceramic filter, etc., have been implemented thus avoiding future flywheel fractures in transit.

Wang Z.,Huazhong University of Science and Technology | Wang Z.,University of California at Berkeley | Chen X.,Huazhong University of Science and Technology | Chen X.,DongFeng Commercial Vehicle Co. | And 6 more authors.
Fuel | Year: 2016

Although exhaust gas recirculation (EGR) is widely implemented to suppress the NOx, it can increase soot emissions and decrease the thermal efficiency in internal combustion engines. Water-emulsified diesel is a promising alternative approach, as it decreases soot emissions, suppresses NOx formation, and promotes thermal efficiency through improved mixing between the fuel and air. Based on the inhibiting functions of oxygen dilution and emulsified diesel on engine emissions, a visualization study on the spray combustion of water-emulsified diesel was experimentally explored in a constant volume combustion chamber at various ambient oxygen concentrations. This study firstly examined the different combustion characteristics of water-emulsified diesel and pure diesel. Secondly, the effects of ambient oxygen concentration on combustion characteristics of water-emulsified diesel and pure diesel were investigated. Furthermore, the characteristics of soot formation and oxidation during the combustion process were revealed by flame features observed using optical techniques. Experimental results showed that a micro-explosion arose in the emulsified diesel spray which promoted mixing between the fuel and air. Local temperatures were reduced due to water's high specific heat and latent heat of vaporization, which also played important roles in ignition. The high specific heat and latent heat of vaporization had stronger effects than micro-explosions in the combustion process. The combined functions of the micro-explosion event, specific heat and latent heat of vaporization significantly decreased the soot emissions in water-emulsified diesel. Additionally, the ambient oxygen concentration affected the integrated flame luminosity and soot formation of the water-emulsified diesel. However, there were no obvious effects of the explored ambient oxygen concentrations on the ignition limit, flame boundary and flame area. The results showed that when the requirement of NOx emissions was held constant, the use of water-emulsified diesel could decrease the need for oxygen dilution by 10%. © 2016 Elsevier Ltd. All rights reserved.

Ma Z.,Huazhong University of Science and Technology | Yang J.,Texas Tech University | Jiang M.,DongFeng Commercial Vehicle Co. | Zhang Y.,Huazhong University of Science and Technology
SAE Technical Papers | Year: 2015

A new recursive method is presented for real-time estimating the inertia parameters of a vehicle using the well-known Two-Degree-of- Freedom (2DOF) bicycle car model. The parameter estimation is built on the framework of polynomial chaos theory and maximum likelihood estimation. Then the most likely value of both the mass and yaw mass moment of inertia can be obtained based on the numerical simulations of yaw velocity by Newton method. To improve the estimation accuracy, the Newton method is modified by employing the acceptance probability to escape from the local minima during the estimation process. The results of the simulation study suggest that the proposed method can provide quick convergence speed and accurate outputs together with less sensitivity to tuning the initial values of the unidentified parameters. Copyright © 2015 SAE International.

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