Question

2. Assume that the graphite epoxy reinforced plastic with longitudinal fibers 25% graphite fibers. The elastic modulus of the fibers is 320 GPa and that of the epoxy matrix is 110 GPa. Calculate the elastic modulus of the composite and the fraction of the load supported by the fibers.

Answer 1

Answer:Elastic modulus of the composite =162.5GPa; Fraction of load supported by fibres=0.4923

Step-by-step explanation:

Elastic modulus of the composite s given by

Ec= XEf + (1-X)Em

where

Ef=Elastic modulus of the fibre = 320GPa

X=Cross sectonal area of fire= 25%= 0.25

Em= Epoxy matrix= 110GPa

Ec= XEf + (1-X)Em

= 0.25(320)+ (1-0.25) 110

=80+0.75x 110

=80+82.5

Elastic modulus of the composite =162.5GPa

b) Fraction of load supported by fibres is given as

Pf/Pm= Ef/Em/(Ef/Efm+ Vm/Vf)

=320/110 / ( 320/110 + 0.75/0.25)

2.9090 / (2.9090+3)

2.9090/5.9090

=0.49229≈0.4923

Fraction of load supported by fibres=0.4923