Composite Materials: Matrix, Fibers & Mechanical Properties

[examorph]

So I have been reading up on composite materials and have been geting a bit confused, from what I have read, composite materials consist of a matrix and reinforcement, the reinforcement can be fibers, I read that the way the fibres are placed will effect the machanical properties of the material does anyone know how this will be effected?

 

[examorph]

What I ask above may not be clear enough, I was reading at it said that if fibres are all layed out in the same direction a force at a different angle would easily break the material, the example I saw was tensile strength, what else would fibre alignment effect?

 

[AlephZero]

I'm not really sure what you are asking here, but you try to break a composite material where all the fibers are in one direction, if you apply a force in some directions you have to break the fibers, in other directions you many only have to break the bond between the fibers and the matrix, and in some directions you only have to break the matrix material.

What else could fibre allignment effect? Just about every material property. Stiffness, strength, toughness, thermal expansion coefficient, thermal and electrical conductivities, etc, etc. Of course what is actually affected will depend on what a particular composite material is made from.

 

[examorph]

Thank you for the reply, what is the effect of using more reinforcement and less of the matrix material would it make the composite material much stronger?

 

[pukb]

Depends on the reinforcement (rein) type and purpose used for. If it is for improving strength, increasing reinforcement fraction would increase the strength until there is enough matrix material to hold them together; provided all other factors such as orientation, interface etc are kept under control.
If rein is added to improve conductivity, the distribution, orientation and interface must be controlled to increase conductivity. Generally it is much easier to obtain higher conductivity with lower fraction of rein.

 

[examorph]

Thanks