volume change in the composite? (20 pts.)

4. An aligned, continuous fiber composite has 30% weight of fiber. The dimension of the composite is shown in figures below. Given the fiber modulus is 5GPa, fiber density is 1.6g/cm3; the matrix modulus is 100MPa, matrix density is 0.8g/cm3. Poisson's ratio for the fiber and matrix is 0.1 and 0.3, respectively. If the there is a tensile stress of 60MPa applied to the composite along the fiber direction (a), perpendicular to fiber direction (b), as shown in the figures below. Please calculate (1) the modulus of the composite, (2) the percentage of change in the surface areas of the composite under the tensile stress in figure (a) and (b), respectively. (3) Compare (a) and (b), which one results in a larger volume change in the composite? (20 pts.) (a)