This design incorporates a bike-like frame structure with optimum weight to strength ratio. No curved elements are used in the design, only straight tube sections, which are cut and joined using some combination of welding, structural epoxy, and metal fasteners. The frame is made from oversized tubing, which reduces weight while increasing safety; absorbing impact energy, increasing stiffness, and optimizing loading.
It is composed of two side-rings (shown in blue), and a front sub frame (red and yellow). The two side-rings are constructed flat and in a single plane, similar to a bike frame. The oversized rectangular box sections of this frame help absorb energy during impact. Connecting the eight straight tube elements that compose each side-ring are reinforcements (sown in gray), which are constructed from various thicknesses of plate metal, and joined to the ring assembly. Each of the reinforcement plates provide multiple functions; to serve as structural reinforcements, joining members for the elemental tubes that constitute the side-ring, and as mounting locations for adjacent cross-members (shown in green) and local hardware--such a door latches, lights, and suspension.
Key to the simplicity of this design is that the side-rings are constructed easily on any flat floor. The seven cross-members that join the two halves of the frame are bolted to reinforced regions on the side-rings—eliminating the need for any complex vehicle assembly fixtures. The entire ring is a serviceable assembly, which can be replaced. In alternate forms, this frame could be constructed as a one or more pieces using such processes as hydroforming, which would give the frame optimum strength and reliability.
Rear crush-zone
During high-speed rear impacts, due to the frame geometry, the rear wheel impacts upon the rear floor panel, while the rear suspension pushes the vehicle upward--an optimal acceleration angle for the vehicle occupants.
Frontal crush-zone
The frontal sub-frame consists of upper and lower support arms, designed to collapse during impact. The spare wheel is mounted to the front sub-frame cross-member, helping to add crash resistance, and pushing directly on the upper and lower front sub-frame arms. The forward floor is designed to prevent any intrusion into the occupants space.
Side crush-zone
The oversized rectangular box sections of this frame, with their relatively thin walls, collapse and absorb energy during impact. Yet it is the polycarbonate shell that provides the bulk of side impact safety.
