Optimal Polar Wavelet Transform for Damage Detection in Laminated Composite Circular Plates

This study introduces an optimal polar wavelet transform for damage detection in laminated composite circular plates. The core concept behind the proposed method lies in strategically selecting the most informative polar detail signals to extract damage-related information from vibration mode shapes. To guide this selection process, a minimum energy ratio (MER) index is introduced as a benchmark for identifying the most effective polar wavelet function by evaluating the energy balance between the approximation signal and the various detail signals. To generate reliable vibration data for the proposed damage detection framework, the mathematical model for the circular plate has been developed based on the first-order shear deformation theory (FSDT), neglecting damping effects to simplify the analysis. By introducing central and non-central finite elements, the solution is calculated using the finite element method (FEM), and a convergence study is conducted to verify the accuracy of the numerical model. The effects of different parameters such as location of damage, level of damage, noise, number of layers, and lay-ups on detecting the damages of laminated composite circular plates are considered numerically and experimentally. Results show that the developed optimal wavelet transform can more accurately predict the location of the damage compared to the traditional polar wavelet transform.