206 き裂による非線形圧電インピーダンス変調現象の解析(セッション6 スマート構造システム(2))

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In this paper, a nondestructive, in-service structural integrity monitoring methodology that can detect and characterize local structural damages of contact-type, i.e. damages and failures which come along with generation, growth and/or changes of contacting surfaces, such as cracks, debonding, preload-loss in bolted joints, etc., is presented. The presented monitoring system consists of piezoelectric elements bonded on the structural surface, a high-frequency harmonic voltage source, and a current detector. When the piezoelectric elements are driven by a fixed amplitude high-frequency harmonic voltage source, and the structure is excited by low-frequency external load, the nonlinear effects of vibro-acoustic interaction between the low-frequency vibration and the high-frequency wave field at the contact-type damages causes the amplitude and phase modulation of the current flowing through the piezoelectric element. A modeling and analytical study of the nonlinear piezoelectric impedance modulation is presented in the case of single mode excitation both in quasi-static and dynamic conditions. The comparison between the modulated admittance functions solved under both conditions has validated the damage evaluation measures constructed under the quasi-static assumption.
2009-12-08