On the static and fatigue life of nano‐reinforced Al‐GFRP bonded joints under different dispersion treatments

Abstract

As bonded components of engineering structures inevitably experience fatigue loading conditions during their service life, it is significant to find ways to enhance their endurance. Also, adding nanoparticles to the adhesive can be introduced as an approach to design more durable bonded joints. In this way, it is important to determine a nanoparticle dispersion method which can lead to the longest fatigue life. Accordingly, this paper aims to investigate the influence of various nanoparticle dispersion treatments on static and fatigue responses of aluminum‐to‐composite bonded joints under four‐point bending. For this purpose, four dispersion techniques of mechanical stirring, bath‐sonication, low‐power and high‐power probe‐sonication were used to disperse nanoparticles into the adhesive. Also, four specimen groups of neat (with no additive particles), graphene nano platelet (GNP)‐reinforced, nano silica‐reinforced, and hybrid‐reinforced (including GNP + nano silica) were prepared. Results indicated that, for the joints including GNPs, the longest fatigue life was achieved for the specimens prepared by low‐power sonication method, while for hybrid‐type reinforcements, using high‐power method led to the highest endurance. Moreover, for 0.5 and 1.0 wt.% of nano silica, the endurance of bath‐sonicated specimens was 12.77% and 9.28% longer than low and high‐power probe‐sonicated joints, respectively. Using the backface strain (BFS) measurement technique, the influence of dispersion methods was studied on extending the crack initiation life (CIL) of each joint group. It was revealed that, for 0.5 wt.% and 1.0 wt.% of nano silica, the CIL is independent of the dispersion method, while, for 1.5 wt.%, probe sonicated specimens had the longest CIL. The microstructural characterization of each dispersion method and major reinforcing mechanisms were interpreted by scanning electron microscopy (SEM). For future researches, using X‐ray tomography and health monitoring methods is recommended to detect size and location of damage for nanoparticle reinforced composite structures.

Probing the effect of post-curing and halloysite nanotube reinforcement on thermo-mechanical properties of lightweight epoxy syntactic foam composites

“…After sonication, the dispersion was poured into the epoxy resin and agitated at 800 rpm for about 30 min to ensure homogeneity in the dispersed mixture. According to earlier researches, 42,43 adding acetone to the resin nanoparticle mixture and then subjecting it to a sonication procedure resulted in a noticeable increase in the mechanical properties. However, the amount of epoxy used for the current investigation was comparatively larger.…”

Influence of moisture absorption on the compressive behavior of halloysite nanotube reinforced buoyant nanocomposite foams for maritime applications

“…The morphology of HNTs shown in Figure 7 depicts the crack‐pinning effect involving the creation of such a network of obstacles that impedes the propagation of cracks in the matrix. The reinforcement effect involves adding strength and stiffness to the matrix through the incorporation of high‐strength and high‐aspect ratios of nanofillers 66–68 . These mechanisms make epoxy composites with nanotubes better suited for high‐stress applications such as aerospace, automotive, and maritime industries.…”

“…The reinforcement effect involves adding strength and stiffness to the matrix through the incorporation of high-strength and high-aspect ratios of nanofillers. [66][67][68] These mechanisms make epoxy composites with nanotubes better suited for high-stress applications such as aerospace, automotive, and maritime industries. Figure 8 shows peculiar features of HNTs, showing a hollow lumen (Figure 8A), which is capable to carry epoxy resin into the lumen and thus exhibits efficient stress transfer in the composites, as corroborated by our previous study.…”

An experimental investigation on the thermal and mechanical characterization of boron/flax/PLA sustainable composite

“…It is seen in Figure 3(e) and (f) that the weight percentage of boron compounds increases from 3 to 5 wt%, causing more agglomeration of boron compounds. Zamani et al 31 reported that the addition of more hybrid weight content increases the size of agglomerated particles in the composite. While the high surface area/volume ratio of the particle boron fillers enhanced the YM and FM, a little agglomeration in the composite structure caused a reduction of about 11–12% in the tensile and flexural strengths.…”