Numerical Frequency Prediction of Combined Damaged Laminated Panel (Delamination Around Cut-out) and Experimental Validation.

Purpose: The natural frequencies of the layered composite panel with combined damage have been performed numerically considering the debonding between the consequent layers of laminae around the Cut-out. The damage influence on structural strength has been studied to investigate the realistic responses. Methods: Initially, the cut-out abided panel model is derived with the help of a computational tool (ABAQUS) with and without delamination. Moreover, the computational model is derived via a quadrilateral shell element (four-noded) with twenty-four degrees of freedom (DOF) per element. The responses are computed by taking the influences of the individual damages and the combined cases, i.e., the cut-out, debonding, and cut-out associated with the delamination. Results: The outcomes are compared with the recorded experimental frequency values for the combined influences of damages. The comparisons between the simulation and experimental data of the first mode of fundamental frequencies indicate a close relevance with a deviation of ± 10%. After establishing the comprehensive behavior of the computational model, the same has been extended to evaluate different sets of examples by changing the geometrical and/or material-dependent parameters. Conclusions: The stiffness of the structure is affected by the presence of delamination and cut-out in specific shapes. However, the structure having circular delamination and cut-out exhibits high stiffness compared to the other two cases. [ABSTRACT FROM AUTHOR]