Talk Composites - The Forum for Advanced Composites

Materials for a Porsche widebody redesign.

http://www.talkcomposites.com/Topic34038.aspx

By Boski - 10/22/2019 8:11:28 PM

Hello everyone, I am looking for some help.
I want to take my Porsche car (987S), add some clay like material to the existing body and form widebody panels and then continue with mould preparation for carbon fiber. My question is: do you have any suggestions on what materials to use to add on the car in the first process of widebody positive moulding?

In design studios they build the car from brown/reddish clay. However, adding clay to the existing body may be a bad idea for many reasons, there is quite a lot of volume to add which translates into a lot of weight, it puts strain on the suspension and may just not stick. I am wondering what is the best technique, for example using some light wood ribs over the existing body, then filling the gaps between the ribs with foam and adding skin on top. But this would require a lot of time, and wouldn't be easily adjustable. I was thinking about creating volume from some hollow objects, for example scrunching some hydrophobic film (like paper) and adding plaster on top to create a shell of the desired shape.

But I really don't know what is the way to go and I would appreciate your input! Maybe you know of some lightweight materials that are good for this purpose?

Thanks!
By Boski - 10/23/2019 3:30:25 AM

Polyurethane foam... Sounds like a good material, can you add more when you take too much off in the process of sculpting? I guess you are right about the weight.
Also the detail - is it possible to have a foam without any large air bubbles? I suppose there is different foam chemistry to chose from. Matte finish is ok because the part will painted afterwards for gloss finish. Also - some positive moulds will be composed of both native car body and new added material, so the parts won't be taken off for the process of negative mould preparation. Maybe this picture explains it better, this is a part of the design (it's raw without any photoshop fireworks). As you see the rear fender is partially made of clay and partially made of the native car skin. Transition is supposed to be seamless to produce a single panel. In reality it adds 7cm per side.




I think I need ribs for this, just like you mention the symmetry problem. 

I will add more pictures as I go, obtaining the design in 1:18 scale took a month already and I think I got it, but need to clean up the pictures in photoshop before sharing. 

Thanks again!