Assignment 5 (30 points) 1. (5 points) Compute the longitudinal and transverse stiffness E1, E2 of an S-glass epoxylamina for a fiber volume fraction Vf = 0.7, using the properties from attached Tables. 2. (5 points) Plot the longitudinal stiffness E1 of an E-glass/nylon unidirectionally reinforced composite, as a function of the volume fraction Vf of fiber. Use the properties from attached Tables. 3. (5 points) Plot the longitudinal tensile strength of an E-glass/epoxy unidirectionallyreinforced composite, as a function of the volume fraction of fiber, assuming tensile strength follows a volume rule of additivity. Use the properties from attached Tables. 4. (5 points) What is the maximum volume fraction of spherical fillers that could be obtained in the particle-reinforced composite assuming cubic packing? Please show the step. 5. (4 points) Using the Takayanagi model and assuming uniform strain in the matrix, derive a relationship for the transverse, tensile compliance of a unidirectionally-reinforced composite. 6. (6 points) Two test specimens have the same Young’s modulus in tension. However, one of the specimens is homogeneous while the other one has two layers with one layer stiffer than other layer. How will the flexural modulus of the two specimens differ? Explain. (Hint, use Parallel and Series model to calculate the modulus to compare them. Assume the modulus of stiff material is 1X109MPa as and the modulus of soft material is 1X108 , and the volume fraction of each one is 0.5) Properties will be used for solving above problems: The modulus of S-glass is 85.5 GPa, the modulus of E-glass is 72.4 GPa, the modulus of Epoxy is 3.5 GPa and the modulus of polyamide (nylon) is 3.0 GPa. The tensile break strength of E-glass is 2.4 GPa and that of epoxy is 45 MPa. The break strain for E-glass and epoxy is 2.6% and 1.28%, respectively.
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