Abstract. Inappropriate air vent design always induced porosities in thin and complex shape of high pressure diecasting (HPDC) products. Chill block installation was preferred to improve permanent molds for reducing porosities. There were not regular to obtain an appropriated chill vent from this method unless an experience of mold makers. This research was performed to investigate and evaluate the chill block performance in the HPDC mold of motorcycle fuel caps. The HPDC mold of the thin and complex shape product without chill vents was improved by inserting of chill blocks. The motorcycle fuel caps of molds with and without chill vents were compared to verify size and position of porosity defects. Furthermore the HPDC simulation using the finite element analysis (FEA) had been performed according to the physical experiment. The FEA results were compared and in agreement with the experimental data. Therefore an improvement of the HPDC mold should be used FEA to obtain the best way of the air vent design.

Hydroplaning is a hydrodynamic phenomenon and has crucial effects on motorcycle tires that roll on a wet road at high speed. It causes an accident that results in numerous injuries and deaths of motorcyclists. This accident happens to an overestimation of the dynamic tire performance. Therefore, this research aims to propose a mathematical model to predict the maximum hydroplaning speed of motorcycle tires. The motorcycle tire was experimentally performed the hydroplaning test by the developing machine. The fluid-structure interaction (FSI), in which a rolling tire interacted with fluid on the road, was modeled using finite element and finite volume methods. It compared against the experiment and was in good agreement. Therefore, motorcycle tire hydroplaning was studied by varying velocities, inflation pressures, and carrying loads. It was found that the hydroplaning speeds had a serious relationship only to the carrying loads. Therefore, the novel function of hydroplaning velocity was established in the carrying load form. It is simple to specify the maximum hydroplaning speed of motorcycle tires. In addition, it will be a good and novel guidance tool for motorcycle riding communities and motorcycle tire manufacturers to calculate hydroplaning resistance of their motorcycle tires.