ENHANCEMENT OF THE OPEN HOLE TENSION PROPERTIES OF THE NANOCOMPOSITES USING CARBON NANO-COILS

Laminated composite materials offer high specific strength and specific stiffness for low weight, making them widely used in fields like the aerospace, energy, and automotive industries. Holes are a crucial design feature in assembling multiple composite parts, which is a common practice in various structures. The holes act as stress concentrators, creating the need to understand the effects of holes on composites to design safe parts. The addition of nanomaterials to an epoxy matrix has been shown to increase the strength of polymer composites. Previous research, most of which has focused on straight carbon nanotubes (CNTs) and other nanomaterials, found improvements in the open-hole tensile strength of composite laminates through the addition of these materials in the polymer matrix. Helical carbon nanotubes (HCNTs) have been found to have some advantage over straight CNTs (SCNTs) due to their three-dimensional heli coil shape that provides stronger interlocking within the matrix. The goal of this research is to investigate the effects of CNTs on the open-hole tension (OHT) properties of polymer nanocomposites by comparing pristine SCNTs, pristine HCNTs, and functionalized straight CNTs. In this research, two different weight percentages (i.e., 0.025wt% and 0.05wt%) of three different CNTs were added to epoxy resin to fabricate test specimens. These specimens were then cut in to coupons, holes were drilled at their center, and an open-hole tension test was performed per the ASTM standard D5766/D5766M – 23. The test results from this pilot study showed improvements in the tensile strength, tensile modulus, and strain at failure of polymer nanocomposites reinforced with CNTs when compared to the results of neat epoxy samples.