Lamb Wave Excitation and Detection with Smart Fasteners for Structural Health Monitoring

摘要

Recently, a new design concept for multifunctional fasteners using smart materials was proposed by the authors. These piezoelectric devices, named 'smart fasteners,' can be fabricated by modifying the design of ordinary fasteners such that they have a piezoelectric transducer and a control unit embedded in their body. These smart fasteners can not only clamp structural members like ordinary fasteners but also induce or detect structural responses. In this paper, the capability of the smart fasteners to excite and detect Lamb waves in the clamped structure for structural health monitoring is presented. For this purpose, a mathematical model for the Lamb wave excitation with the smart fasteners is derived first using the potential function method. By applying the space domain Fourier transform, the model is transformed into the wave number domain where the boundary conditions are applied to get the solution. The obtained solution is then converted back into the physical space using the inverse Fourier transform. Finally, closed-form solutions for the surface displacements are obtained using the residue theorem in the complex plane. With the analytic solutions, mode tuning capabilities of the smart fasteners are analyzed and then experimentally verified.