Proceedings of Meetings on Acoustics vol:16 pages:045019-045019
International Conference on Nonlinear Elasticity in Materials edition:17 location:Cefalu date:1-7 July 2012
Nonlinear acoustic techniques have proven to be extremely sensitive to early stage damage detection. However, the main issue preventing widespread use of these techniques is that they require high amplitude waves to induce the nonlinear response. As an alternative to transducers bonded to the test material, a more practical realization consists of developing non-contact ultrasonic transducers capable of generating high amplitude waves. Time reversal (TR) techniques are particularly suited to concentrate sound energy at a chosen location in space and at a specific instance in time. In this paper, it is numerically demonstrated how TR and a "candy can" (i.e. a highly scattering, contained medium) can be used to create a focused, high amplitude non-contact transducer. We developed and investigated the results of a finite element model of the "candy can" concept. The model allows to demonstrate the concept in different situations and illustrates the ability to pre-calibrate the non-contact source in air. The results of the simulations allow a better insight in the new concept and will be used in a further stadium for optimization of the high amplitude non-contact source.