Numerical And Experimental Studies On Damage Detection Of Laminates Based On Electromechanical Impedance Technology

Because of their excellent characteristics, such as high specific strength and specific stiffness, good thermal stability, good capability of fatigue resistance and corrosion resistance, composite materials have been widely used in the aerospace industry and other fields. Due to the influence of the processing and working environment, composite structures often occur many defects and damage which will seriously affect the overall performance of the composite structures during processing and using. In view of this situation, the damage detection technology of the composite has become an important direction in composite research. This paper studied the damage detection technology of the composite laminates based on electromechanical impedance technology.First of all, this paper introduced and analyzed the mechanics of composite materials and the theory of the electromechanical impedance technology. The relationship between the mechanical impedance of the structure and the piezoelectric impedance of the PZT in the coupling system was obtained. And the factors that affect the PZT coupled electrical admittance were discussed. These analysis provided a theoretical basis for structure damage detection based on electromechanical impedance technology.Secondly, numerical analysis of the damage detection of composite laminate based on electromechanical impedance technology was conducted by ANSYS. The three-dimensional finite element models of the two PZTs damage detection system and three PZTs damage detection system were established. Through comparing each PZT conductance curves in different damage cases, this paper analyzed the influence of structure damage on PZTs, determinated and evaluated the position and the degree of the damage in the structure according to the damage criterion of cross-correlation coefficient(CC). The numerical analysis based on finite element method verified that the electromechanical impedance technology was effective and feasible for damage detection of composite laminates, and it provided an importantreference value for the subsequent experiment.Finally, experiment analysis of the damage detection of composite laminates was conducted based on the numerical analysis results using the impedance analyzer WK6500 B. The conductance curves of the PZTs under different cases that the laminates with different damage locations and degree were measured. Through comparing and analyzed the conductance curves in different damage cases, it was found that the experiment results and the numerical analysis results had good agreement, and verified the electromechanical impedance technology could successfully detect the laminate damage. At the same time, this paper studied the damage location analysis in laminate and verified that using distributed PZTs for damage detection can preliminarily predict the damage location in the structure.