Numerical Simulation And Experimental Study On Defect Detection For Composite Structure Using Piezoelectric Impedance Method

Steel-concrete composite structures have been extensively used in large-scale and complex civil engineering projects.It is a challenging task to detect interface debonding and cavity defects in concrete-steel composite structures by traditional nondestructive test(NDT)approaches and it is critical to develop novel and efficient approaches to detect unaccessible interface debonding and cavity defects in concrete-steel composite structures.In this study,a defect detection approach based on piezoelectric impedance measurement for concrete-steel composite structures is proposed,and numerical and experimental studies on the mechanism of the proposed approach are carried out.The major work includes the following aspects:(1)The methods and basic principle of structural damage identification based on piezoelectric impedance measurement for concrete-steel composite structures are introduced.The test setup and work flow of piezoelectric impedance based on damage detection method are described in detail,and the frequency band selection and corresponding analysis methods are described systematically.(2)Based on the finite element analysis theory of piezoelectric ceramics harmonic response.The finite element modeling method of the numerical simulation of impedance analysis of steel-concrete composite structure and piezoelectric materials is introduced systematically.And the finite element theory model of piezoelectric analysis based on ANSYS numerical simulation is outlined.(3)After analyzing the behavior of free PZT patches,piezoelectric slice was modeled and analyzed for the selection of test frequency bands.A multi-physics coupling analysis model is established with ANSYS by considering the electromechanical coupling effect between PZT patches and the composite structure and piezoelectric performance of PZT patches.The simulated impedance frequency curve of structural models with various defects is analyzed.(4)Experimental study on the defect detection of concrete-steel composite structured models with artificial interface debonding and concrete cavity defects based on impedance measurement is carried out.PZT electrical impedance values are tested by surface mounted and embedded piezoelectric sensors and the damage index defined based on the impedance frequency curve diagram is employed to detect the defects.