The research on the identification method of element-level damage indicators for composite laminate structures with uncertainties

This paper introduces an element-level damage indicator named laminated elemental stiffness parameter (LESP) tailored for composite laminates, which can comprehensively reflect the damage status of the in-plane and out-of-plane stiffness of laminates. An optimization method based on the sensitivity matrix for identifying element-level damage indicators is developed. To quantify the influence of measurement noise on the identification results, a method for identifying the uncertainty of element-level damage indicators is proposed. Considering the nonlinear impact of structural damage parameters on structural response processes, the damage probabilities are defined inspired by the advanced first-order second-moment method. Considering the correlation effects of different damage modes for each element, a comprehensive damage probability (PCD) model is established to achieve the uncertainty assessment of structural damage. Numerical examples are performed to verify the proposed methods and the effects of noise levels, modal orders, and damage extent on identification results are analyzed. Through numerical examples, it is found that the correlation coefficient has a greater impact on the PCD. Finally, the proposed method is validated through experimental work.