MECHANICAL PROPERTIES OF GRID COMPOSITE SANDWICH PANELS REINFORCED WITH NATURAL COTTON FIBERS WITH SQUARE AND RHOMBOID-SHAPED CORES: EXPERIMENTAL STUDY AND NUMERICAL SIMULATION

The mechanical properties of grid composite sandwich panels reinforced with natural cotton fibers with square and rhomboid-shaped cores (ribs) were studied. The sandwich panels were made of natural cotton fibers and polyester resin and produced using the hand lay-up method. The ribs, made in three types with six, eight, and ten layers (number of cotton natural fibers), and skins, made in four layers, were vital elements in our investigation. We explored the effect of ribs' thickness (number of fiber layers) and core shape on the mechanical behavior of sandwich panels. Panels were then subjected to a three-point bending test, a widely accepted method for evaluating materials' flexural strength and stiffness. The resulting load-displacement curves provide valuable information about the material's behavior under load. In addition, bending stiffness, flexural strength, core ultimate shear strength, facing ultimate bending strength, and energy absorption values were calculated for each sandwich panel. Also, the panels were numerically simulated in Abaqus, a highly reliable software known for its accuracy, and the numerical results were compared with the experiment. The results further validated the accuracy of our methods. The results, which demonstrated the square core's superiority in bending stiffness, flexural strength, and energy absorption, have profound implications for the design and development of advanced composite materials in the field of materials science and engineering.