Unhole and open hole tensile properties of hybrid Kevlar/glass fiber polymer composites with different stacking sequence

The effects of stacking sequence play a vital role in determining the mechanical properties of fiber reinforced polymer composite materials. This study was conducted to investigate the effects of a hole and unhole Kevlar/glass fiber hybrid composite specimens at four different stacking sequences. Other than stacking sequence, the damage tolerance properties were also analyzed in this study to find out the strength reduction between the hole specimen and the unhole specimens. The damage fractured on the surface of the specimens was also analyzed through macroscopic observation and scanning electron microscope. All the specimens in this study were fabricated using vacuum bagging method according to the ASTM D5766 for open-hole tensile test. In the open-hole tensile test, unhole and hole hybrid composite specimen (H4) with alternate layered fiber, projected the highest value of tensile properties. The alternate layered fiber can improve the interlaminar adhesion; thus, increase the tensile strength as compared to the sandwich stacking sequence (H2 and H3). Based on this study, GFRP and hybrid composite specimens displayed approximately 40%-50% strength reduction, while KFRP recorded only 30% of strength reduction. From the damage observation, the failure characteristics change from fiber pull out in glass fiber composite to fiber breakage in Kevlar fiber composite specimens. (c) 2020 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the Innovative Manufacturing, Mechatronics & Materials Forum 2020.