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With the growing demand of weight reduction in recent years, hollow structural casting products, which are weldable, of high strength and rigidity, are produced by high-pressure die-casting. In order to develop such a cast product in a short period of time, techniques are required to predict the castability, weldability, strength, quality at an early stage of development. The conventional simulations, however, are unable to satisfy the aforementioned demands. In an attempt to respond to those demands, the authors through this reported research quantifiably analyzed the porosity in the casting, and realized predicting of actual strength and elongation. By applying the newly developed casting simulation to the motorcycle parts, the cast part design can be accurately verified, allowing signification reduction of the thickness and weight.

In motorcycles, the materials of frame have been switched from steel to aluminum for the purpose of reducing weight while improving the rigidity of chassis. It was made possible to use aluminum frames for a number of commodity categories, by the development of technology through new structural designs to make the most of the characteristics of aluminum, the advancement of computer simulation system and the progress in material and production engineering. As the result of adopting aluminum for the frame, much higher performance has been realized by achieving a 40% reduction in the developed frames consisting of extrusions and castings for sports-oriented motorcycles and by suppressing the increase in fuel consumption. For low-priced utility vehicles such as scooters, the manufacturing process has been simplified by the development of the die cast two-split module frame.

Since 1987, we have been studying the liquid-gas two phase fluid loop and trying several kinds of cold plates in order to provide large platforms in the future. This report describes the following in connection with the two-phase fluid loop. An outline of the recent trial manufacture of the two phase fluid loop provided with a bellows-type flow control system, which can be used in space. New type cold plates featuring porous fin. Tests results confirming that the loop and heat exchangers have adequate operational characteristics.