A uniaxial composite material is made from 75 vol %t continuous kevlar fibers and 25 vol %t epoxy. The kevlar fibers have an elastic modulus of 131×109 Pa and a tensile strength of 4.0×109 Pa. The epoxy resin has an elastic modulus of 5×109 Pa and a tensile strength of 50×106 Pa.

(a) In a uniaxial test to failure, what component will fail first, and at what strain?
(b) What is the composite stress at fracture of the first component?
Assume that both the kevlar fibers and the epoxy matrix are elastic up to their failures.


(a) The kevlar fibers failure strain is:







(b) Assume that each component is elastic the composite stress at fracture of the matrix.



Physics & Space Science

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