Influence of nano-reinforcement on the mechanical behavior of adhesively bonded single-lap joints subjected to static, quasi-static, and impact loading

In this study, the effects of nano-reinforcement on the mechanical response of adhesively bonded single-lap joints with composite adherends subjected to different loading (strain) rates are systematically investigated. The results are then compared to those of the neat thermoset resin and a toughened acrylic–epoxy adhesive. More specifically, nano-reinforced and neat resin-bonded joints mating carbon/epoxy and glass/epoxy adherends were subjected to tensile loadings under 1.5 and 3 mm/min and tensile impacts at a loading rate of 2.04E + 5 mm/min. In some cases, additional tests were conducted to obtain the enhancement in properties that could be gained using the nano-reinforcements for use in our further numerical investigations. The other loading rates tried were 15, 150, and 1500 mm/min. The high loading rate tests were conducted, using a modified instrumented pendulum equipped with a specially designed impact load transfer apparatus. The dispersion of nanoparticles was facilitated using a mechanical stirrer and a three-roll mill machine. The results of the impact tests revealed the positive influence of nano-reinforcements on the loading rate sensitivity of the joints. In all, the overall stiffness and strength of the joints increased as the nano-reinforcement and loading rates were increased. The failure surfaces were then examined with a scanning electron microscope to observe the distribution of the nanoparticles and study the mode of failure.