Propagation, scattering and mode conversion of guided waves in presence of asymmetrically located damage are studied through experimental and numerical simulations using piezo actuators
and sensors. Difficulties encountered in identification, localization and quantification of damage in presence of multimode and interaction of propagating wave with scattered and reflected waves are presented. The fundamental antisymmetric (Ao) mode is more suitable in localizing and
quantifying the damage. It is shown that the mode converted guided wave could be advantageously used for identification, localization and quantification of damage. Piezo electric wafer transducers are used for generating and sensing the guided waves. Practical aspects of implementing piezo transducers for wave generation and sensing are presented. A damage identification and localization scheme is evolved based on the location of the sensor with respect to the damage. The
quantification of damage is derived experimentally based on the strength of the voltage signal reflected from the damage. 3D finite element based numerical simulations modeling the PZT sensor are carried out and validated with experimental results in terms of the characteristics of the waves, mode conversion due to damage and influence of the defect size on the received signals. A spectral finite element for modelling of wave propagation, scattering and mode conversion in isotropic waveguide with asymmetric damage is developed. Frequency based spectral element method is employed to formulate a ‘damage spectral element’ incorporating a notch type damage and numerical simulations conducted. The damage zone is modeled as three structural waveguides and formulated by enforcing appropriate force equilibrium conditions. The damage spectral
element is applied for predicting response of a cantilever beam with damage and validated experimentally. The proposed damage spectral element is able to predict the wave scattering and mode conversion due to presence of damage and the results agree well with the experimental ones. Parametric studies by varying the damage size is conducted and the predictions are consistent with experimental measurements.