Interlaminar shear behavior of unidirectional glass fiber (U)/random glass fiber (R)/epoxy hybrid and non-hybrid composite laminates

The interlaminar shear behavior of unidirectional glass fiber (U)/random glass fiber (R)/epoxy hybrid composites was studied with short beam shear bending test. Random glass fiber (R)/epoxy means chopped fiber composite having short discontinuous fiber randomly dispersed in epoxy matrix. The effect of stacking sequence and unidirectional glass fiber relative volume fraction (V-fU/V-fT) on the interlaminar shear strength (ILSS) of the manufactured composites has been investigated experimentally and theoretically. The laminates were fabricated by hand lay-up technique with 5 plies. Two non-hybrid composite laminates {[}R](5) and {[}U](5) were fabricated using the same fabrication technique for the 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. Experimental results indicated that the ILSS of {[}U](5) is higher than those of hybrid and {[}R](5) composite. Hybrid composites have higher ILSS than that of random composites. The stacking sequence and (V-fU/V-fT) ratio have a detectable effect on ILSS of the investigated composites. (C) 2012 Elsevier Ltd. All rights reserved.