Question

There are 2 types of Fiber-reinforced composite material. Continuous (aligned) and discontinuous(random or aligned)
If we have aligned composite, how can we know it is discontinuous? And what is difference with random discontinuous?

Answer 1

This is the well known and most important composite because of having a discontinuous phase or disperse phase in the form of fiber.

Basically, it has 3 phases - the first one is the discontinuous or dispersed phase, continuous phase, and interface.

Now, How can we know this?

Actually, these phases are nothing but just depend on the orientation of fiber and some other parameters.

So if these are aligned or it means having a parallel arrangement of fiber Longitudinal axis along a single direction then it is a continuous phase.

But for discontinuous it may be aligned, randomly distributed or oriented, and maybe partially oriented.

Now your question is if it is aligned composite then how can we decide whether it is continuous or discontinuous?

I assume that you already know the concept of fiber length influence on fiber-reinforced composite.

As fiber length increases then fiber reinforcement becomes more essential.

Lc, be the critical length.

If L>>Lc, these termed as continuous.

If L<<Lc, then it is termed as Discontinuous or also short fiber.

Critical length is the minimum length i.e. required to transfer the entire load from matrix to fiber

- If we have aligned fiber composite and satisfy the condition i.e.Fiber are longer than its critical length. then it is continuous (aligned) fiber composite.

- If we have aligned fiber composite and satisfy the condition i.e.Fiber are shorter than its critical length then it is discontinuous (aligned) fiber composite. These having less strength than continuous with aligned fiber. These are less costly than continuous with aligned fiber composite. and it is easy to fabricate.

Basically aligned fiber composite depends on both property of matrix as well as fiber and these are anisotropic.

If you have any doubt please ask in comment section.

Thank you.