Optimized toughness of short fiber-based composites: The effect of fiber diameter

The effect of fiber diameter change on the toughness of short fiber polymer-based composites is studied by assuming that the main energy absorption upon fracture is the fiber pull-out mechanism. An expression is derived for a characteristic fiber length, ℓ∗, distinct from the critical length, above which an increase in fiber diameter always yields an increase in composite toughness. Experimental validation is provided through impact testing of composites made of short polyethylene terephthalate fibers in a polypropylene matrix.