A dynamic equilibrium-based damage identification method free of structural baseline parameters : experimental validation in a two-dimensional plane structure

Abstract

A damage identification method named the pseudoexcitation (PE) approach was established previously, the principle of which resides on local examination of perturbation of structural dynamic equilibrium conditions. While showing significant sensitivity to structural damage with small sizes, the approach exhibited high vulnerability to measurement noise owing to the involvement of high-order derivatives of the vibration displacements in the expression of the damage index. On the other hand, several baseline parameters (e.g., Young’s modulus and density) are necessary to implement the approach and limits the practical application of the approach. A weak formulation of the PE approach was established to circumvent the interference from measurement noise. However, the weak formulation of two-dimensional (2D) structural component has not been developed, and the reliance of the weak formulation on baseline parameters remains an unsolved issue. In this paper, the 2D weak formulation of the PE approach was proposed by introducing a weighting function in terms of the 2D Gauss function. Through an integration operation, the selected weighting function was able to significantly highlight the feature of structural damage and largely suppress noise influence. Furthermore, a statistical strategy was developed to inversely estimate the values of baseline parameters, which signifies the elimination of the dependence of the PE approach on preobtained baseline parameters. As a proof-of-concept investigation, multidamage in a plane structure consisting of both beam and plate components were identified by using the modified damage identification method. A hybrid data fusion algorithm was then used to enhance the accuracy of damage detection, revealing not only the locations, but also the sizes of damaged zones.