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The adhesive bonding approach is widely used in assembling of spars, stringers, ailerons, flaps, and rudders in aircraft. The present research investigated the impact of silicon carbide (SiC) nanoparticle inclusion on the shear and free vibrational behaviour of adhesively bonded single lap joints (SLJ). The shear test results showed that the inclusion of 1.5 wt.% SiC in the epoxy resin enhanced the shear behaviour of adhesively bonded SLJ. Furthermore, the failure surfaces of adhesively bonded SiC-reinforced SLJ were examined using a field emission scanning electron microscope (FESEM). The microstructural investigation of the failure surface demonstrated that the development of rougher surfaces, plastic void enlargement, and formation of shear bands in the joint region had improved adhesion among GFRP adherends. Thus, the SiC-incorporated adhesively bonded SLJ had predominant cohesive failures. Meanwhile, the SiC-free lap joint had an adhesive failure due to lower adhesion. The vibrational results avowed that 1.5 wt.% SiC-incorporated adhesively bonded SLJ has higher natural frequencies. Results also affirmed that higher wt.% SiC-incorporated joint had better modal damping values due to nanoparticle accumulation, which increased the interaction between glass fiber reinforced polymer (GFRP) adherends. [ABSTRACT FROM AUTHOR]

On-site construction projects typically employ staggered fastener patterns. This article describes the application of Hollo Bolts (HB). It also highlights the effectiveness of using flexible epoxy adhesive to increase the load-carrying capacity of staggered connections fastened with HB. The distribution of loads between connecting elements largely determines joint performance. Pultruded glass fiber reinforced polymer (PGFRP), bolted (B), and hybrid bolted/bonded (BB) double lap joints were subjected to a typical pulling load and numerically validated in this investigation. To simulate delamination effects, a Cohesive Zone Model with a 3D progressive damage analysis was developed. In addition, a parametric study capturing the influence of various geometrical variables such as e/d, overlap length, bolt size, adherend thickness, and the number of bolts was used to compare both categories of joints in detail. The results indicate that for staggered connections fastened with HB, an efficient load transfer can be obtained in conjunction with flexible epoxy adhesive. It is anticipated that this interaction will be even more effective as the overlap length, adherend thickness, and fastener diameter increase. The present study proves that BB connections are 43.56% stronger than B connections. [ABSTRACT FROM AUTHOR]

This study investigates the impact of marble powder as a part of fine aggregate and the addition of glass fiber on the bond strength of concrete and deformed high-strength post-installed steel rebars using the epoxy chemical as an adhesive. Five marble dust powder (MDP) substitution percentages (i.e. 0%, 10%, 20%, 30%, and 35%) and the addition of glass fiber (i.e. 0.5%, 1%, and 1.5%) were used. The performance of deformed high-strength post-installed rebars in conventional concrete and concrete modified with 35% marble powder and 1% glass fiber was examined here utilizing pull-out tests on a total of 96 specimens. To examine the bond behaviors of deformed high-strength post-installed rebars at the epoxy–conventional concrete interface and epoxy-modified concrete with MDP and glass fiber interface, test criteria included concrete compressive strength, anchorage depth of rebar into concrete, rebar diameter, and concrete cover to rebar diameter ratio. For post-installed high-strength deformed rebar, bond stress–slip relationships were determined, examined, and subsequently compared with prior work and readily available codes. It was found that none of the specimens exhibited pull-out failure and that the majority of them displayed concrete splitting, concrete rapture, or rebar rapture failure. This suggests that epoxy resins are particularly successful as bonding agents to retrofit concrete structures at the steel–concrete contact. A closed-form equation for predicting the bond strength for post-installed high-strength deformed rebar was also created using regression analyses on the experimental data. With a significant coefficient of determination (R2 = 0.85) the observed predicted bond strengths and the test data were quite similar. [ABSTRACT FROM AUTHOR]