| Oil consumption reduction and performance enhancement have become the development trend of road vehicles, especially of motorcycles. Due to their nature of high-speed motion and rotation, weight reduction of the wheels is the most efficient way to reduce the oil consumption, to improve the accelerating and braking performance, enhance the riding comfort of a road vehicle. Naturally, use of light weight materials on the wheels is the most straight-forward way to achieve the goal. In comparison with most widely used aluminum alloys, magnesium alloys are the lightest commercialized metallic material for structural applications. Mg alloys possess the attractive properties desired by motorbikes, such as low density, low cost, higher specific strength, good casting properties, out-standing damping capability. When used as wheel material, Mg alloys are able to reduce mass of the wheels, to absorb vibration, to damp noise emission, to reduce oil consumption, to enhance acceleration and braking performance and the resultant riding comfort. However, the Mg alloys cannot be directly used on the commercial wheels because Mg alloys possess material properties considerably differing from those materials, such as steel or Al alloys, to which the wheel is designed for. To ensure the performance and safety, the service condition of the wheels has to be analyzed and the structure of the Mg wheels have to redesigned to in accordance with the materials properties of Mg alloys. To promote a scientific understanding on the effect of material substitution and structural features on the service condition of wheels, numerical analyses of stress and strain distribution in wheels of both 356 Al alloy and AM60B Mg alloy under service condition were performed, and the 150 Mg wheel structure was redesigned and optimized with finite element method (FEM). The obtained important results were high-lighted as follows: 1) The use of tilted supporting bar and the small transition curve in 150 wheel gives rise to stress concentration at transition segments. The stress distribution in the rest part of the wheel is even. In the rest of the wheel, the stress level is comparatively low and the strain distribution is uniform. 2) Replacement of Al alloy A365 with Mg alloy AM60, service stress distribution in the wheel becomes more uniform, the peak value of the concentrated stress reduced from 36.4MPa to 27.1MPa, down by 25.6%. The stress distribution in the wheel as a whole trends to become more uniform and variation during a service cycle becomes much smaller. This is because the low elastic modulus of Mg alloy permits the wheel structure to undergo more intensive elastic deformation, witch, in turn, transfers the load more widely to the whole wheel, creating a pattern of 'Global Load Sharing'. 3) Considering the fact that Mg alloy has a lower fatigue strength, the tilt angle between the hub and spoke and the transition curves at both ends of spokes were modified during structure optimization so that the peak service stress was further reduced from 27.1MPa to 23.1MPa, down by 14.8%, to strengthen the service reliability and safety. Guided by the above results, 150 motorbike Mg alloy wheels were redesigned and produced with a patented novel squeeze casting process with 30% weight saving. Their service properties were tested in the laboratory of an authorized organization and by a 8000 km tough road-test via Sichuan-Tibet and Tibet-Qinghai country road organized by Loncin motorbike company. It is evident that the Mg alloy wheel possesses significantly improved service performance and an oil consumption reduction of more than 14%.
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