Free vibration analysis and prediction modeling of delaminated tapered FRP composite plates

Delamination (the separation between plies) is a common failure in Fiber Reinforced Polymer (FRP) laminated composites. The presence of delamination reduces the structural stiffness and changes in dynamic responses. The change in dynamic parameters can be successfully used for assessing structural health monitoring (SHM) for composite structures. SHM requires large amount of numerical/experimental data. This study focuses on the influence of the delamination parameters (size and in-plane location) on vibration behavior of a laminated tapered fiber reinforced polymer (FRP) composite plate with ply drop-off. Furthermore, developing a surrogate model as a fast-executing model to predict the shift in the natural frequency to reduce the computational effort for solving forward problems. The layerwise theory (LWT) has been used, and the delamination is modeled by “constrained mode” were solved using the finite element method (FEM). The numerical model was validated with an experimental modal analysis of tapered plates without delamination to make the model more robust. The effect of delamination was studied using surface plots produced using response surface methodology (RSM). The results show that the delamination size and location significantly affect the natural frequency shift. The RSM and ANN models were considered as surrogate models, and it was evaluated using an experimental modal analysis. The results shows that the single-output ANN model can predict the shift in the natural frequency with a minimum Root Mean Square Error (RMSE).