Evaluation of Material Integrity Using Higher-Order Harmonic Generation in Propagating Shear Horizontal Ultrasonic Waves.

Material nonlinearity is explored for the assessment of structural integrity. Crack-wave interactions are of particular interest. The major focus is on higher-order harmonics, generated in propagating shear horizontal (SH) waves.

Directivity and Excitability of Ultrasonic Shear Waves Using Piezoceramic Transducers-Numerical Modeling and Experimental Investigations.

In this paper, piezoceramic-based excitation of shear horizontal waves is investigated. A thickness-shear d piezoceramic transducer is modeled using the finite-element method. The major focus is on the directivity and excitability of the shear horizontal fundamental mode with respect to the maximization of excited shear and minimization of Lamb wave modes.

Modelling nonlinearity of guided ultrasonic waves in fatigued materials using a nonlinear local interaction simulation approach and a spring model.

Modelling and numerical simulation - based on the framework of the Local Interaction Simulation Approach - was developed to have more insight into nonlinear attributes of guided ultrasonic waves propagating in fatigued metallic materials. Various sources of nonlinearity were considered in this modelling work, with particular emphases on higher-order harmonic generation and accumulation of nonlinearity along wave propagation. The material hyper-elasticity was considered in the model using an energy density approach based on the Landau-Lifshitz formulation; and the "breathing" motion pattern of a fatigue crack in the material was interrogated using a spring model.