Papers by Author: Hong Liang Yi

Abstract: The FEM was used to analyze the stress distribution of a motorcycle frame on the condition of normal running, starting up, turning and braking, respectively. Having been carrying on the 2000km of running test, the initial design motorcycle frame was found several cracks or fractures in the bending points of the square tube and in the welding seam, whose reasons were analyzed then. The metallographical structures of materials and crack parts of the frame were observed and analyzed and Q235. Based on the results mentioned above, the Q345 steel(Chinese steel mark) was used to replace the Q195 steel in the bending square tube and the prop of the steering column. And the welding and manufacture processes were optimized and improved. Finally, the motorcycle frame whose materials had been optimized could keep running in good condition and satisfy the demands after 16000km of running test.

Abstract: The crankshafts of semi-finished products were manufactured by two processes: as-cast followed by normalizing and iron mould with sand liner as-cast. Then those were machined and nitridized followed by the bending fatigue test. At last mechanical properties and impact properties of sampled crankshafts were tested. The mechanical properties are similar in the crankshafts treated by both of the processes, however, the bending fatigue limits of as-cast spherical graphite iron crankshafts are much higher than that of normalized spherical graphite iron crankshafts, whose crack producing work and extending work is higher as well. The higher extended work is considered to relate to the oeil-de-boeuf ferrite and graphite structure and pearlite in as-cast spherical graphite iron crankshafts, while the normalized ones with lower fatigue limit value are composed of spherical graphite and pearlite. Cracks having initiated in the graphite, the tips of cracks can be blunted and the crack propagation can be impeded efficiently by ferrites surrounding the graphite in this structure.

Abstract: Ultrafine TiO2 powders as rutile and anatase phase were simply precipitated at room temperature for only tens of hours by simply controlling the pH value and Ti4+ concentration via aqueous TiCl4 solution. Under the optimal pH value and Ti4+ concentration, the average particle size of powders with rutile phase was 3.7nm, while that of powders with anatase phase was 3.0nm. The average particle size was calculated from the broadening of corresponding X-ray spectral peaks by Scherrer formula. In addition, 3.0 mol.l-1 are suggested to be used as concentration of stock solutions instead of the current concentration 2.0 mol.l-1.

Abstract: There are three common empirical expressions used for the fatigue curves, which are power function, exponential function and three-parameter power function expression, respectively. The mathematical difference between the former two and the latter is whether there exists the constant term S0 in the equations. The S0 can be calculated to determine whether the two-paprameter expression or three-parameter expression should be used. If the two-parameter expression should be used, the power function and exponential function expressions can be compared to determine which one is the optimum one. Finally, the method has been validated by several groups of fatigue data.