Simulation of Air-Coupled Transducer Operation in Structural Health Monitoring Systems

Non-contact (air-coupled) transducers have been increasingly used for structural health monitoring (SHM), along with the traditional method of ultrasonic guided wave excitation and registration by an array of piezoelectric wafer active sensors. The development and successful application of such diagnostic systems are based on the mathematical and computer modeling of the wave processes occurring here. This paper deals with the models based on the integral and asymptotic representations of excited waves through the Fourier symbol of Green’s matrix of the coupled system source–acoustic environment–elastic waveguide. Compared to traditional finite element simulation, the developed models have advantages such as low computational costs, the visibility of the wave structure, and the ability to solve the problems of selective mode excitation and maximization by choosing the optimally tilted transducer and central frequency. The verification of the developed model and choice of the optimal parameters for the source operation are illustrated by numerical examples.