Ulrich T J, Johnson Paul A, Guyer Robert A
EES Division, Geophysics Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Phys Rev Lett. 2007 Mar 9;98(10):104301. doi: 10.1103/PhysRevLett.98.104301. Epub 2007 Mar 7.
This Letter reports on work performed to locate and interrogate a nonlinear scatterer in a linearly elastic medium through the use of a time reversal mirror in combination with nonlinear dynamics. Time reversal provides the means to spatially and temporally localize elastic energy on a scattering feature while the nonlinear dynamics spectrum allows one to determine whether the scatterer is nonlinear (e.g., mechanical damage). Here elastic waves are measured in a solid and processed to extract the nonlinear elastic response. The processed elastic signals are then time reversed, rebroadcast, and found to focus on the nonlinear scatterer, thus defining a time-reversed nonlinear elastic wave spectroscopy process. Additionally, the focusing process illuminates the complexity of the nonlinear scatterer in both space and time, providing a means to image and investigate the origins and physical mechanisms of the nonlinear elastic response.
本信函报告了通过使用时间反转镜结合非线性动力学，在线性弹性介质中定位和探测非线性散射体的相关工作。时间反转提供了在空间和时间上把弹性能量定位到散射特征上的方法，而非线性动力学频谱则使人们能够确定散射体是否为非线性的（例如机械损伤）。在此，弹性波在固体中进行测量，并经过处理以提取非线性弹性响应。然后，对处理后的弹性信号进行时间反转、重新传播，发现其聚焦于非线性散射体，从而定义了一种时间反转非线性弹性波谱学过程。此外，聚焦过程揭示了非线性散射体在空间和时间上的复杂性，提供了一种对非线性弹性响应的起源和物理机制进行成像和研究的方法。
