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 (VfU/VfT) 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 (VfT) 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 (VfU/VfT) ratio have a detectable effect on ILSS of the investigated composites.