Design

To begin with, the chassis is merely a big bracket keeping all components in the right place. It seems simple, a few tubes build around all the key components of the car. But it quickly becomes a bit more complicated than that. How are the tubes going to fit with each other, how do we make sure that the welds are within the desired tolerances, how do we avoid unwanted bending of tubes, how are the load paths, how can we improve rigidity and reduce weight, is the car safe to drive? – This is just some of the questions that arise when the chassis are designed. 

Last year we realized, that the chassis is probably the last of the big components that should be designed, although it’s the first to be build. It is easy to change the frame geometry to fit other components than it is to say change how the suspension behaves or are the battery cells are assembled, and so on. In comparison to last year, the frame is lighter, and stronger, using fewer tubes, simply because of the order in which the components where designed. 

Figure 1. Frame with all the crucial components such as drivetrain, tractive system, pedal box and steering system hidden away by the body panels.

In January 16 students worked on the frame as their final project in the course FEM-light, where they had to investigate the overall strength and rule compliance of the chassis through FEM simulations. Mainly the frame must withstand large forces applied from the accumulator. Other than that, the strength of seatbelt harness positions during crashes where simulated, as well as torsional stiffness and load situations during cornering. This was a great input to help understand how the frame acts during different loading situations, which gained confidence that the frame is rule compliant and safe.

Manufacturing

To make every tube fit with each other, last year, we spend nearly 600 hours preparing and milling the tubes in the workshop. This year we owe a big thanks to our sponsor QuickTube for laser cutting all of our tubes. This improves accuracy when assembling and welding, and it saves precious time, which we can use elsewhere. When the tubes are laser cut, each tube will have taps or holes much like a puzzle, which makes sure that all tubes only are positioned correct in relation to each other. This makes the welding process less confusing and more accurate. 

To further help the welders an assembly guide much like a LEGO instruction will show the order of which the tubes should be welded in. A custom jig made of laser cut sheet metal also helps to hold the tubes in place before they are welded together.

Safety: Impact attenuator & anti-intrusion plate

Motorsports have never been safer than today, however accidents can still happen. 

That’s why all the cars competing must meet strict safety regulations. 

To protect the driver in case of an frontal crash all cars are equipped with an “Impact attenuator”(IA). It is designed to absorb the impact in case of a crash, making the deacceleration less abrupt.