In-plane shear properties of unidirectional glass fiber (U)/random glass fiber (R)/epoxy hybrid and non-hybrid composites

The in-plane shear properties (shear strength tau(xy) and shear modulus G(xy)) of unidirectional glass fiber (U)/random glass fiber (R)/epoxy hybrid and non-hybrid composites have been investigated experimentally and theoretically. The effect of stacking sequence and random fiber relative volume fraction (V-fR/V-fT) in hybrid composites were reported. Laminates were fabricated by hand lay-up technique with a total of 5 plies, by varying the number and position of random glass layers so as to obtain four different hybrid laminates; i.e. {[}0.5R/U/U](s), {[}U/0.5R/U](s), {[}U/U/0.5R](s), and {[}U/R/U/R/U]. All unidirectional fiber laminate {[}U](5) and another of all random fiber laminate {[}1215 were also fabricated for comparison purpose. The average thickness of the manufactured laminates is 5.5 +/- 0.2 mm and the total fiber volume fraction (V-fT) is 37\%. Failure modes of all specimens were investigated. Results indicated that the in-plane shear properties (shear strength tau(xy) and shear modulus G(xy)),) of unidirectional fiber composite can be considerably improved by incorporation of random glass fiber and forming hybrid composites. (C) 2011 Elsevier Ltd. All rights reserved.