Chassis design VDS Fuel Cell Car

This instructable deals with the chassis design and manufacturing of the Fuel Cell Electric Vehicle from the Vehicle Design Summit at MIT.

The Fuel Cell car is a small two person, three wheeled (2 in the front, 1 in the back) car for commuter purposes.

Step 1 Anthropometry and component parts

An important part of the chassis design is to check if a human being fits inside. Anthropometry means the measurement of humans; it deals with the ergonomics of a human being inside a car.

In literature there is information available about anthropometry in the automotive industry:
The standard J1100 of the Society of Automotive Engineers (SAE) has standardized different dimensions for the space available for driver and passengers in cars: it is difficult to find values for these dimensions in J1100
Automotive Ergonomics (Peacock & Karwowski, 1993): deals with several topics of ergonomics and anthropometry in vehicle design; also has values of important dimensions!

At www.3dcontentcentral.com (a free resource for 3D CAD drawings) there is a car seat model available for SolidWorks. With this model and the data available from literature a new model was made in SolidWorks, the so-called forbidden space model. This is a model with a layout of the seat and the space that is needed to accommodate the driver and passenger: this space can not be used for the structure.

Also in this step you need to have a good idea about all other big componentes in the car and how to accomodate them.
(pictures copied from "Automotive Ergonomics (Peacock & Karwowski, 1993")

Comments

[alxram]

Where can I find out more about the fuel cells that will be used to power this car?

[Pal]

The Tesla Roadster is being developed with banks of cell phone batteries as an option over traditional batteries, it seems like an ideal option as you leave the research of battery efficiency to larger companies already working on it for their own benefit and use a lighter, modular system for power.

http://www.teslamotors.com/index.php

[VanBee]

Thanks for your the usefull feedback. The fuel cell people in our group should post a report here, I don't know if they already made one but hopefully they will do it soon. Due to time constraints we were not really able to optimize the design of the frame. All tubes are welded by a very skilled welder. He knew where to drill small holes to avoid local stresses, and there was actually no need for a jig -> I don't know why (I also expected more frame distortion), maybe because of the modular design and the experienced welder... The picture above is not the final design: we've added some extra members for torsional and bending stifness. The central tunnel was designed for extra torsional stifness (the idea was to make a box out of it for stifness and to store samller h2 tanks and cables in). The structural requirements came from solarcar design and are more or less standard. In solarcar design I used the skin of the car to contribute to the stiffness, but in this case there was no time to design the body so we only had the frame to work with...

[foote]

Beam 188 or 189 elements will provide you with a much better visualization of your model, as well as more post-processing options. 188 and 189 use the actual cross-section to calculate stresses, etc. while beam 4 elements can only calculate bending stresses in two orthogonal directions. Also, when you weld a heat treated aluminum, you loose much of the strength about the weld locations and you need to account for this in your chosen design strength. You could heat treat the entire frame back to a T6 state, but it would be VERY difficult to prevent warping during the quench. And I am talking about a lot of warping. I'm really looking forward to some articles on the actual drive train of this thing. Hope they are coming...

[gsport george]

How are you planning on joining the aluminium sections together? Welding is likely to lead to a lot of frame distortion if you dont have a strong jig to restrain it during welding. I also think you will have problems achieving the torsional stiffness you specify unless you add some diagonal members to the floor, sides and roof. Since weight is a major factor you might want to try to let the skin of the vehicle contribute to the torsional stiffness. It would also be interesting to know the specific requirements that led to this design. The central tunnel seems like a slightly frivolous use of material unless there is some obvious purpose for it that you havent mentioned. Good Luck.

[saites2001]

Anything on DIY fuel cells?