Question

(Multiple choice)
Which one of the following statements is true? Explain why T/F for each.
(a) In fiber reinforced composites, the dispersed phase will not have the same composition as
the matrix phase.
(b) When continuous-fiber reinforced composites are loaded longitudinally, the stress in the
fibers equals the stress in the matrix.
(c) Sandwich panels are useful because of their high weight-to-stiffness ratio.
(d) Approximately 30% of the overall strength of fiberglass is contributed by the matrix.
(e) The stiffness of aligned discontinuous-fiber reinforced composites loaded along the fiber
direction depends on the weight fraction of matrix in the composite.

Answer 1

a) True : A Composite Material is a materials system composed of a mixture or combination of two or more micro- or

macro-constituents that differ in form and chemical composition and which are essentially insoluble in each

other. Generally, Composite Materials consist of a Dispersed Phase (Fibers) and a Matrix Phase.

- The Matrix Phase generally surrounds the Dispersed Phase.

- The Dispersed Phase is generally contained within the Matrix Phase

b) False : As Isostrain ( same strain) – referred to as the Longitudinal direction in composite fibres. while Isostress (equal stress) referred to as the transverse direction.

c) True: This is the advantage of sandwich panels that they are made up of two thin layers of a metal a low density core is inserted like a sandwich. So it allows us to design a structure of low weight with a high mechanical strength

d) FAlse : It will depend upong the matrix amount

e) False: It depends upon angle of fibres

d)