Numerical Investigation of Free Vibration in Laminated Composite Plates with Stiffened Cutout

This study utilized SolidWorks 2018 software to numerically investigate the free vibration behavior of laminated composite plates with stiffened cutouts. The plates were cross-ply symmetric laminates consisting of four layers stacked in a (0,90,90,0) degree sequence. Various square plates with different dimensions and configurations were modeled and analyzed, including plates with central circular cutouts, central stiffened circular cutouts, central square cutouts, and central stiffened square cutouts. The results revealed that cutting an opening up to 10% of the plate area led to a decrease in the fundamental natural frequency, while increasing the cutout area beyond 10% resulted in further decreases in the fundamental frequency. Additionally, the natural frequency was found to be influenced by the shape of the cutout and the height of the stiffener. Increasing the plate dimensions showed greater improvement in the natural frequency with a smaller stiffener. The most significant enhancement in the fundamental natural frequency, at 48.3%, was achieved by introducing a circular cutout in a plate measuring 1000x1000mm with a 5% stiffener height relative to the 25% cut area. Similarly, a rectangular cutout at a 10% stiffener height yielded a 42.8% improvement for the same cut area percentage.