Hello,

What are you trying to model? and what layup, resin, carbon grade, resin ratio etc...

The basic properties are widely available online for each type component then depending on the level of analysis you are performing and the software (if using) then you can calculate the the anisotropic stiffness matrix and other properties.

The weave effects the elastic modulus significanty as does the orientation of the fibres. UD is pretty much what the basic E value is but when you get to plain woven or twill then you can have up to a 50% reduction in E BUT by doing this you gain in other areas such as strain to failure as the fibres have to stretch more before failure.

If you have access to a structural testing lab at a university then you can make some basic samples to the various codes then test them to get the properties you want/need

If you simplyfy your model to 2d stress/shell the you only need the X and Y values then calculate the through thickness shear stress separately

It is to model the diffuser of our Formula Student car.

try and find these books in the library or online

Engineering Design with polymers and composites, Gerdeen, Lord & Rorrer - CRC Press ISBN 0-8247-2379-1
Composite Materials design and applications, Gay & Hoa - CRC Press ISBN 1-4200-4519-9
Introduction to design and anaysis with advanced composite materials, S Swanson ISBN 978-0024185549

If you want aero surfaces then use a spread tow woven or UD on the surface as this will reduce any print through.

Model the diffuser as an isotropic material first to ensure it all works when modelling and to see where the stress, strain and shears are plus where the model is likely to deflect. Fromthat you can then work out what and where to put the material.

the layup if using UD will likely be a mix of 0, +/-45 and 90 depending where the stresses go

If you are hand laying (and vac bag?) then you should be able to get at least 50% fibre / resin ratio

Thanks already, I will look for these books and find the right information.

Yes it is very easy but with practice you can get amazingly good results.

Look at the videos on here to get an idea of what you need to use and do but the best way is to get your hands dirty so to speak.

Which Uni are you at?

I'm at the KU Leuven - Campus Group T university in Belgium. If you are interested, our Formula Student team is Formula Group T.

Need some help? :p I'm from Kortrijk, Belgium...