Effect of presence of SWCNT and Fullerene nano particles in the adhesive of CFRP single lap joint on the lap shear strength subjected to hygrothermal conditions

Abstract

In this paper, the effect of adding Single-Walled Carbon Nanotubes (SWCNT) and Fullerene Nano particles to the adhesive of Carbone fiber reinforced plastics (CFRP) single lap joint (SLJ) has been investigated on the lap shear strength of the joint both before and after the applying of the hygrothermal conditions. Different SLJ samples were manufactured containing different percentages (0–5% Vf) of SWCNT, Fullerene and a mixture of both that was designed using Responsive Surface Method (RSM). Hygrothermal conditions of 70 temperature and humidity of 100% was then applied to the samples for the duration of 2 weeks after which, the tensile (lap shear) strengths of the un-aged and aged samples along with the amount of moisture absorption and failure surface of SLJs were measured and compared . The results showed that addition of particles, especially Fullerene decreases water absorption, resulting into increase in the lap shear strength of the SLJ. Hygrothermal conditions decreased the strength in neat adhesive, SWCNT and Fullerene reinforced samples but it increased in the samples with adhesive having mixture of Fullerene and SWCNT. The failure mode of the SLJs were combination of adhesive and cohesive where the hygrothermal condition and addition of the particles increased the area of the cohesive failure zone. Finally it was observed that, the optimum sample has 2.25% Vf of mixture of both SWCNT and Fullerene with lap shear strength 7% higher than the neat adhesive SLJ before hygrothermal aging and 31% after applying of the hygrothermal aging.