An aluminum space frame is the main structure of our recently developed electric vehicle. The frame consists of extruded members. As each extrusion has the same cross section, it is possible to accomplish an optimal design of the whole space frame by setting up design variables for each extruded member.
Size optimization was completed to minimize the weight of the space frame at the desired overall stiffnesses, service loads, and desired natural frequencies. A tray structure was proposed for the batteries of the electric vehicle, and as a result, the overall stiffness was improved. In addtion, it became easier to install the batteries. A method to reduce the weight of tray was tried within the design constraints. Special reinforcements were used for weak parts between each member.
The space frame was modeled as shell elements for the numerical analysis. The structural design of the space frame compensated for the increased weight by batteries making the lightweight, 4-seat, electric vehicle a reality.