Natesan Karthikeyan

Adhesively bonded techniques effectively fuse the structural components in an assembly in aerospace applications. The co‐bonding is more effective than secondary bonding for joining fuselage frames to skins, wing ribs, and spars to skin joints. The flexural behavior and failure analysis of a carbon fiber‐reinforced polymer composite single‐lap joint is one crucial factor in aerospace applications. This research involved the fabrication of co‐bonded carbon fiber‐reinforced polymer composite single‐lap joints utilizing the vacuum bag hand lay‐up method, incorporating geometric modification techniques, including interleaved and covered lamination. The flexural strength was examined through a three‐point bending test. The results indicate that the secondary bonded with covered lamination techniques has attained the maximum flexural strength compared to others. The values are 80% higher than the neat secondary bonded joints. Moreover, the carbon fiber‐reinforced polymer composite single lap joint samples were examined for failure analysis using the ASTM D5573 standard. Furthermore, these geometric modifications in CFRP composite joints confirmed the significant enhancement in experimental results with less than 5% error rates.Highlights: Carbon fiber‐reinforced polymeric (CFRP) joints were made utilizing interleaved and covered lamination methods. SB and CB methods were utilized to fabricate the CFRP composite joints. CL‐SBT exhibits high flexural strength (639 MPa) and modulus (45.94 GPa). A thin‐layer cohesive failure was observed in interleaved CFRP joints, The fiber tear failure was observed in covered lamination CFRP joints.

For aerospace applications, co‐curing bonding is more effective than co‐bonding and secondary bonding for joining fuselage frames to skins, wing ribs, and spars to skin joints. This study investigated the flexural and dynamic behaviors of co‐cured carbon fiber‐reinforced polymeric (CFRP) composite joints utilizing adherend and adhesive‐modified techniques. The adherend underwent modification to incorporate a stepped geometry and adhesive modified by multi‐walled carbon nanotubes (MWNCT). The flexural strength and modulus were enhanced by 13% and 12%, respectively, when using 0.75 wt% multi‐walled carbon nanotube (MWCNT) modified adhesive in co‐cured‐CFRP joints over epoxy adhesive‐stepped adherends. In addition to that, both stepped adherend and 0.75 wt% of MWCNT adhesive in co‐cured CFRP composite joints showed a 261% enhancement in flexural strength and a 45% increase in modulus contrast to plain epoxy adhesive neat co‐cured CFRP composite joints. Interestingly, MWCNTs with a 0.75 wt% demonstrated the highest natural frequencies among all three vibration mode shapes, outperforming the pure adhesive epoxy stepped adherend co‐cured CFRP composite joint by 5%, 2%, and 8%, respectively. The results were investigated using a statistical analysis known as ANOVA. Optimization and prediction were performed utilizing a MATLAB neural net fit tool in conjunction with the Levenberg–Marquardt algorithm.Highlights: Adhesive prepared using six different wt% of multi‐walled carbon nanotubes (MWCNTs) using ultrasonication. Stepped adherend carbon fiber‐reinforced polymeric (CFRP) joints were fabricated by the co‐cure method. Maximum flexural and dynamic behaviors at 0.75 wt% MWCNT in adhesive. Statistical analysis was done using a one‐way ANOVA technique. An artificial neural network predicts the flexural and dynamic behavior of CFRP composite joints.

Cocured bonding and geometric modification are prominent techniques for fusing structural components in aerospace and aircraft applications. This research involved the fabrication of carbon fiber‐reinforced polymeric (CFRP) adhesive‐bonded joints utilizing novel cocuring with interleaved lamination (IL‐CC) joining techniques with multiwalled carbon nanotubes (MWCNTs) modified epoxy adhesive. Additionally, the study examined the flexural and vibration characteristics of IL‐CC CFRP composite joints. The result findings 1.0 wt% MWCNTs in epoxy adhesive had the best flexural strength and modulus, 78% and 32% higher than the pure epoxy adhesive. Additionally, the IL‐CC CFRP composite joints exhibit a 285% higher flexural strength and a 47% higher modulus than the neat CC CFRP composite joints. Nevertheless, the nanofiller with a wt% of 0.25 demonstrated the highest natural frequency across three different vibration modes, which are 14%, 21%, and 25% higher than pure epoxy adhesive. An ANOVA showed that MWCNT concentrations significantly influenced performance. Using the Levenberg–Marquardt algorithm, an artificial neural network predicted results. The overall coefficient (R) mean square error of 0.99627 is satisfactory, indicating that both outcomes are dependable and in good agreement. The results imply that IL‐CC CFRP composite joints could be used in aerospace and aircraft parts.Highlights: The IL‐CC CFRP SLJs were fabricated with MWCNT‐modified adhesive. Attained the maximum flexural strength is 1.0 wt% MWCNT. Attained the maximum natural frequency is 0.25 wt% MWCNT. Statistics were analyzed using a one‐way ANOVA technique. An ANN predicts the flexural and dynamic behavior of IL‐CC CFRP SLJs.