Two way nonlinear manipulation in plane materials using dual frequency pulse complexes

A one dimensional (ID) model based on plane wave, linear acoustics is formulated. It is used to estimate the two way nonlinear delay, τ, obtained in a plane layer using a dual frequency-band method where two pulses with a large frequency separation are transmitted simultaneously and coaxially. For standing waves (SW), the model finds the phase relationship between the high frequency (HF) and the low frequency (LF) pulse which maximizes τ given the boundary conditions (BCs) and the linear acoustic parameters of the layer in addition to the incoming pressure. For short pulse complexes, the model is compared with a ID nonlinear simulation tool based on the spectral element method (SEM) for which the results correspond well. An experiment is performed to study τ as a function of the BCs in a water layer. The measurements is compared with simulations and it is shown theoretically how τ is related to the nonlinearity parameter B/A.