Enhancing shear strength of single lap composite adhesive joint with graphene nano-particles and Z-pins reinforcement through co-curing technique

Adhesively bonded joints play a vital role in improving the structural performance of 3D‐printed components. This research aims to examine the effect of graphene inclusion on the failure load and vibrational behavior of polylactic acid flat‐joggle‐flat (FJF) joints prepared using fused deposition modeling. The present research focused on the effect of print directions (0°, 45°, 90°) and the inclusion of graphene nanofiller (0.25, 0.50, 0.75, and 1.00 wt%) on the performance of FJF joints. The effect of raster direction on mechanical properties was examined by tensile testing of dog‐bone samples. Results showed that 0° print orientation had higher tensile strength compared to other printing directions. Shear testing of FJF joints indicated that the inclusion of graphene has enhanced the strength of 3D‐printed FJF joints by 61.18%. Fractography results showed that the formation of the shear band with the inclusion of 0.50 wt% graphene helps to distribute the stress more evenly and prevent catastrophic failure of the FJF joint. The free vibrational test revealed that the inclusion of 0.50 wt% graphene had improved the natural frequencies, as the presence of graphene‐enhanced the interfacial bonding between FJF adherend and adhesive.Highlights 0° print orientation had higher tensile strength than other printing directions. Inclusion of graphene‐enhanced the shear strength of flat‐joggle‐flat (FJF) joints by 61.18%. Shear band formation delayed the failure of graphene‐reinforced FJF joints. FJF reinforced with 0.50 wt% graphene had adherend failure. FJF joint added with 1.0 wt% graphene had lower natural frequencies.

Enhancing structural performance of 3D‐printed adhesively bonded flat‐joggle‐flat polymer joints with graphene‐reinforced adhesive

Dhilipkumar,

Venkatesan,

Hiremath

et al. 2024

Surface modification of nano‐SiO₂ and its interaction mechanism in the interface of fiber metal laminates: Experimental and MD simulation analysis

Guo,

Zhan,

et al. 2024

In order to optimize the reinforcing effect of nano‐SiO2 on the interface of fiber metal laminates (FMLs), the nano‐SiO2 was treated by ultraviolet irradiation and silane coupling agent for different surface properties. The interaction mechanisms of nano‐SiO2 were studied by mechanical test, chemical analysis, morphology observation, and molecular dynamics (MD) simulation. The results showed that the average failure strength of FMLs with untreated, hydrophilic and lipophilic nano‐SiO2 increases by 31.80%, 48.77%, and 51.38% compared to the FMLs without SiO2, respectively, and the interface fracture energy for those increases by 31.50%, 74.82%, and 21.47%, respectively. The disparity among the properties is primarily attributed to the surface polarity. The surface group of untreated and hydrophilic SiO2 is hydroxyl, which shows stronger attraction to resin but also easy to agglomerate, while the lipophilic is silane group that shows lower polarity, resulting in weaker attraction to resin but easier dispersion within the resin. Specifically, the surface polarity was verified by characterizing the particle center distance and the number of atoms surrounded by the particle in the two‐particle model. Moreover, the simulation revealed that nano‐SiO2 and resin molecules are mainly connected by chemical bond and hydrogen bond to transfer the load.Highlights The mechanism was explored by experiment and molecular dynamic simulation. The addition of lipophilic SiO2 increased the failure strength by 51.38%. The incorporation of hydrophilic SiO2 enhanced fracture energy by 74.82%. The polarity of the surface group of SiO2 affected the agglomeration/dispersion. The SiO2 and resin were mainly connected by chemical bond and hydrogen bond.

Enhanced flexural and vibration behavior of interleaved CFRP composite joints with modified multiwalled carbon nanotube adhesives for aerospace and aircraft applications

Karthikeyan,

Naveen

2024

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.