Mode shape curvatures / modal strain energy

Pandey et al [1991] have identified the absolute changes in mode shape curvature as an indicator of damage.  Zhang et al [1998] have proposed a structural damage identification method based on element modal strain energy, which uses measured mode shapes and modal frequencies from both damaged and undamaged structures as well as a finite element model to locate damage.

Ho and Ewins [2000] have found that higher derivatives of mode shapes are more sensitive to damage, but the differentiation process enhances the experimental variations inherent in those mode shapes. An experimental damage detection investigation of fiber-reinforced polymer honeycomb sandwich beams has been performed by Lestari and Qiao [2005] based on the curvature mode shapes. In these experiments impulse hammer is used for actuation and surface bonded array of PZT sensors are used for acquiring the curvature modes of structure.