Question

A unidirectional composite is made up of:

25 volume % of fiber type 1 (E = 300 GPa, Poisson's ratio n = 0.25), 25 volume % of fiber type 2 (E = 100GPa, Poisson's ratio n = 0.25), and 50 volume % of a matrix (E = 60 GPa and n = 0.30). The tensile strength of fiber type 1 is 500MPa, that of fiber type 2 is 100MPa, and that of the matrix is 200MPa. Draw a tensile stress- strain curve for the composite loaded along the fiber direction, assuming that each phase responds elastically, then fractures. In particular, indicate

a. the initial slope of the stress-strain curve

b. the strain at which the first phase fractures and the corresponding stress.

c. the strain at which the second phase fractures and the corresponding stress.

d. the peak stress expected for this composite and the corresponding strain.

Answer 1