- (15 pts) List five different advantages of compositematerials over conventional materials.
- (15 pts) Calculate the modulus of elasticity of afiber-reinforced polymer composite under isostrain condition if thecomposite consists of 35% fibers and 65% polymer by volume. Also,calculate the percentage of load carried by the fibers. The modulusof elasticity of the fibers and the polymer are 345 GPa and 3.5GPa, respectively .
- (20 Pts) A fiberglass composite consists of epoxymatrix reinforced with randomly oriented and uniformly distributedE-glass fibers. The modulus of elasticity of the glass fibers andthe epoxy are 70 GPa and 6 GPa, respectively. Calculate the modulusof elasticity of the fiberglass if the volume percentage of fibersis (a) 25%, (b) 50%, and (c) 75%. Plot a graph showing therelationship between the modulus of elasticity of the fiberglassand the percent of fibers. Comment on the effect of the percent ofglass fibers on the modulus of elasticity offiberglass.
- (30 pts) A short reinforced concrete column issubjected to a 1000 kN axial compressive load. The moduli ofelasticity of plain concrete and steel are 25 GPa and 207 GPa,respectively, and the cross-sectional area of steel is 2% of thatof the reinforced concrete. Considering the column as a structuralmember made of a composite material and subjected to load parallelto the steel rebars, calculate the following:
a. the modulus of elasticityof the reinforced concrete
b. the load carried by each ofthe steel and plain concrete
c. the minimum requiredcross-sectional area of the column given that the allowablecompressive stress of plain concrete is 20 MPa and that theallowable compressive stress of plain concrete will be reachedbefore that of steel.
d. Plot the stress-strainbehavior for the steel fiber, concrete and composite on the sameplot.
