Development And Design Of Magnesium Alloy Electric Bicycle

Electric bicycles, characterized by their portability, energy-efficient andeco-friendly, have become mainstream daily short-distance personal transportationmeans. However, most of the electric bicycles on Chinese market do not meet theweight and speed limits of QB1880-2008. Therefore, the main task of the present studyis to develop a new electric bicycles with Mg framework based upon an ordinary oneattracting the enterprise parterner in Sichuan Province, to obtain a lithium batterypowered Mg electric bicycle that not only meets the weight and speed limits of ChineseNational Standard, but also has a high-end market position.Based on the preceding studies and with full respects to processing peroperties ofMg alloys, the present author proposed to produce a solid piece of Mg framework bybolt-joining two die-cast symmitrically half Mg framework castings that is capable ofhousing lithium rechargable in an elegent manor. To obtain a lithium rechargable batterypowered Mg electric bicycles with such a Mg framework,3D modeling, servicemodelling, stress analysis, virtue processing, structure optimization, componentsselection, virtual assembly, performance evaluation have been performed with moderndesign and virtue testing methods in accordance with the technical route for Mg productdevelopment. Then, the weight, performance and cost of the Mg bicycles wereevaluated.The main tasks and conclusions of the present study are detailed as follows.①It was proposed to produce a solid piece of Mg framework by bolt-joining twodie-cast symmetrically half Mg framework castings. Then the numerical model of theframework was constructed.②With lithium battery and Mg framework, the main components of the bicycleswere selected, a new electric vehicle was numerically designed and the main parameterswere determined.③The service models of the bicycle and its framework were established and theservice conditions of the framework is analyzed followed by structure optimizationbased on the design criteria of Mg products. The maximum service stress in theframework was limited under40MPa, and its stiffness and modula meet the designrequirements as well. The optimized frame weighs about1.55kg, compared with steelstructure frame reduce4.25kg. ④A strict comparison of the new design with the old one was performed from theviewpoint of technological economics with consideration of processing cost, security,production equipments, and service cost. The results show that the new bicycles reducethe service annual cost by￥10.64in comparison with the old.⑤All components have been selected followed by construction of their digitalmodels. Then, numerical model of the Mg alloy lithium electrical bicycles wasconstructed by virtual assembly of all the components. The production cost of thebicycles was calculated as￥1,493.32RMB and the weight is20.3kg. If the market pricewas￥2,133RMB, the cost-performance ratio of the bicycles is competitive to itscounterparts on the market due to its weight and energy-saving.