AutoSpeed: lightweight, simple composite construction technique (monocoque + body)

[MechEngVT]

I met with a plastic thermoforming company once and they showed me a sample of a material that's fairly new that made me think of plastic monocoque construction. I seem to recall that it was produced by twin-sheet thermoforming polycarbonate into alternating "egg-crate" shapes to produce somewhat of a sandwich product about 3/4" thick. The two sheets would adhere to one another where one sheet's "bucket" touched the opposing sheet, and the patterns interlocked. If one could take this product in sheet form and thermoform it into more complex shapes it could be a very strong construction material (the 4" x 4" sample I saw did not flex when I put as much abuse to it as I could by hand).

Polycarbonate and carbon fiber both have a disadvantage regarding human crash protection: the human body will not "reject" the shards of foreign material.

[MetroMPG]

FYI, part 2 is up:

Building an Ultra Light-Weight Car, Part 2

It talks about shaping the body with "Adfoam ‘M’ grade modelling type expanded polystyrene blocks"





Wish I knew how to get me some of that stuff. Maybe I should talk to the engineering dep't at my old university. They're not too far away.

I have to admit I was a little disappointed that they subcontracted out the finishing steps, after the shape was glassed (sent it to a bodyshop for fairing the imperfections and paint). Getting an "automotive" grade finish may be the single most time-consuming part of doing work like this.

Building an Ultra Light-Weight Car, Part 2

[jjackstone]

Owens-Corning Foamular is extruded polystyrene. Can be bought in sheets of varying thicknesses. It's the pink stuff. Almost impossible to buy directly here in Cali--too warm. But you could probably find it in any northern state or country at whatever major home improvement box-store retailer of your choice.
JJ

[roflwaffle]

Originally Posted by MechEngVT

Polycarbonate and carbon fiber both have a disadvantage regarding human crash protection: the human body will not "reject" the shards of foreign material.

Could you elaborate?

[aerohead]

Originally Posted by Compaq888

I've seen a lot of new research places build carbon fiber cars that weigh less than 2000lbs. The auto manufacturers refuse to do that. At least BMW started putting in CF roofs, got to start somewhere.

I believe the carbon fiber for the GM Ultralite cost $13,000( US),in 1990 dollars.That was just for the material.It is light and it is strong,and kinda pricey.Carmakers in the US are required to do Total Life Cycle Cost Analysis,which implicates recycling at the end of the car's service life.So far,recycling of carbon fiber structures has posed challenges to mass production.--------------------------- Also,some consider carbon fiber to be the new asbestos.Texas Tech University was given a bunch of aerospace quality pre-preg epoxy carbon fiber material and the university decided not to let the students work with it,concerned over the health implications and liability of dust inhalation.Jury's still out on this one.