It is desired to produce an aligned and continuous fiber–reinforced epoxy composite having...

It is desired to produce an aligned and continuous fiber–reinforced epoxy composite having a maximum of 40 vol% fibers. In addition, a minimum longitudinal modulus of elasticity of 55 GPa (8 × 106 psi) is required, as is a minimum tensile strength of 1200 MPa (175,000 psi). Of E-glass, carbon (PAN standard modulus), and aramid fiber materials, which are possible candidates and why? The epoxy has a modulus of elasticity of 3.1 GPa (4.5 × 105 psi) and a tensile strength of 69 MPa (11,000 psi). In addition, assume the following stress levels on the epoxy matrix at fiber failure: E-glass, 70 MPa (10,000 psi); carbon (PAN standard modulus), 30 MPa (4350 psi); and aramid, 50 MPa (7250 psi). Other fiber data are given in Tables B.2 and B.4 in Appendix B. For aramid fibers, use the minimum of the range of strength values provided in Table B.4.

Table B.2 Room-Temperature Modulus of Elasticity Values for Various Engineering Materials

a Secant modulus taken at 25% of ultimate strength.

bModulus taken at 100% elongation.

cMeasured in bending.

Sources: ASM Handbooks, Volumes 1 and 2, Engineered Materials Handbooks, Volumes 1 and 4, Metals Handbook: Properties and Selection: Nonferrous Alloys and Pure Metals, Vol. 2, 9th edition, and Advanced Materials&Processes, Vol. 146, No. 4, ASM International, Materials Park, OH; Modern Plastics Encyclopedia ’96, The McGraw-Hill Companies, New York, NY; R. F. Floral and S. T. Peters, “Composite Structures and Technologies,” tutorial notes, 1989; and manufacturers’ technical data sheets.

Table B.4 Typical Room-Temperature Yield Strength, Tensile Strength, and Ductility (Percent Elongation) Values for Various Engineering Materials

aThe strength of graphite, ceramics, and semiconducting materials is taken as flexural strength.

bThe strength of concrete is measured in compression.

cFlexural strength value at 50% fracture probability.

Sources: ASM Handbooks, Volumes 1 and 2, Engineered Materials Handbooks, Volumes 1 and 4, Metals Handbook: Properties and Selection: Nonferrous Alloys and Pure Metals, Vol. 2, 9th edition, Advanced Materials&Processes, Vol. 146, No. 4, and Materials&Processing Databook (1985), ASM International, Materials Park, OH; Modern Plastics Encyclopedia ’96, The McGraw-Hill Companies, New York, NY; R. F. Floral and S. T. Peters, “Composite Structures and Technologies,” tutorial notes, 1989; and manufacturers’ technical data sheets.