A space frame structure design for an electric vehicle

The objective of the study was to design a structure for an electric vehicle (EV). This vehicle was specially designed for the elderly. It provided the facilities to accommodate a wheelchair, to monitor the physical conditions of passengers, and the necessary space for extra carry-on accessories. When there was no wheelchair on board, folding chairs attached to the vehicle body or to the driver's chair were available. With different weight distributions, package layouts, power transmission systems from the internal combustion engine vehicle (ICEV), the structure of an EV should be redesigned. Especially, with limited cruising range of an EV, light weight was critical to the vehicle design. A weight and package layout for the EV was developed. A vehicle style was designed with consideration of easy access and being mobile freely for wheelchairs. For better weight reduction opportunity, an aluminum space frame (ASF) design concept was proposed. Fiber-reinforced plastic (FRP) body exterior panels were used for further weight reduction. On the other hand, ASF also provided cost effective designs with extruded structures and generic joints. This reduced the complexity of the body structures and assembly process. With a given proposed vehicle style, a topology optimization using HyperWorks/ OptiStruct was performed for the initial structure design. Based on the topology optimization result, an initial structure design was created using SolidWorks. Detail designs were then carried out using HyperWorks/RADIOSS for lighter weight and functional performance improvements. Both sizing and shape optimizations were considered in the design. The design is retrofitted on an existing internal combustion engine vehicle. A roughly 30% of body weight reduction was achieved from the baseline vehicle.