Dynamic crack growth propagation of Al 2024 thin plates reinforced with carbon nanotube subjected to non-proportional cycling loading

In this study, the dynamics crack growth in a thin plate made of aluminum alloy 2024T3, which was coated with two types of coating, electrocoating (Ni-CNTs) and electroless coating (Ni-CNTs), were investigated under a non-proportional cyclic loading. Pure multi-walled carbon nanotubes (MWCNTs) were added to the coating solution at a concentration of 2 g/l to enhance the mechanical properties and study the effect of adding carbon nanotubes to the coating solution.Fracture mechanics analysis was performed using two methods. First, a novel apparatus was designed for experimental analysis of the application of a non-proportional cyclic loading, consisting of a repeated, cyclic inplane shear stress with constant tension stress. Secondly, the numerical analysis was carried out using ABAQUS 2019 programming to obtain numerical results and compare them with the experimental results to validate the study. Paris law parameters, including Paris law constants c and m, K (change in stress intensity factor), and da/dN (crack growth per cycle), which were included in the ABAQUS software to simulate the model and compare the results with the experimental data.The specimens were analyzed using XRD, FESEM, and EDXRF after the coating process to determine the quality, distribution, and thickness of the coating layer on the specimen's surface. The hardness tests showed a 57% increase in the hardness of the specimens coated with electrocoating and a 72% increase in the hardness of specimens coated with electroless coating. The Young's modulus also showed an increase of 37.5% for specimens coated with electrocoating and 50% for specimens coated with electroless coating, compared to specimens without coating.