450 非線形電気機械インピーダンス変調法 : き裂を有するはりのモデル化と解析(構造物および機械の診断,OS-11 システムのモニタリングと診断,総合テーマ「伝統を,未来へ!」)

概要

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In this paper, a nondestructive, self-sensing, baseline free structural health monitoring methodology is presented, based on a nonlinear piezoelectric impedance modulation phenomenon which is induced by the contact acoustic nonlinearity (CAN) at the 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. For an illustrative example, a mathematical model of a straight beam including a single transverse crack, coupled with a surface- bonded piezoelectric element is derived, utilizing the linear time- varying system theory. The time-varying admittance of the piezoelectric element is formulated in terms of a Zadeh's time-varying transfer function, and its first and second-order approximation is derived. The appropriateness of the first-order approximate which is called frozen-parameter solution is then discussed, and a damage evaluation index is presented based on this solution.
2010-09-14