Pecorari Claudio
Marcus Wallenberg Laboratory, Department of Aeronautics and Vehicle Engineering, Royal Institute of Technology, 100 44 Stockholm, Sweden.
J Acoust Soc Am. 2003 Jun;113(6):3065-72. doi: 10.1121/1.1570437.
A theoretical investigation of the nonlinear interaction between an acoustic plane wave and an interface formed by two rough, nonconforming surfaces in partial contact is presented. The macroscopic elastic properties of such a nonlinear interface are derived from micromechanical models accounting for the elastic interaction that is characteristic of spherical bodies in contact. These results are used to formulate set of boundary conditions for the acoustic field, which are to be enforced at the imperfect interface. The scattering problem is solved for plane wave incidence by using a simple perturbation approach and the harmonic balance method. Sample results are presented for arbitrary wave polarization and angle of incidence. The relative magnitude of the nonlinear signals and their potential use toward the nondestructive evaluation of imperfect interfaces are assessed. In particular, attention is drawn to the enhanced nonlinear response of an interface insonified by a shear vertical wave in the neighborhood of the longitudinal critical angle. The motivation for this investigation is provided by the need to develop nondestructive methods to detect and localize small, partially closed cracks in metals with coarse microstructures.
本文对平面声波与由两个粗糙、不匹配且部分接触的表面形成的界面之间的非线性相互作用进行了理论研究。这种非线性界面的宏观弹性特性是从微观力学模型推导出来的，该模型考虑了接触球体所特有的弹性相互作用。这些结果用于制定声场的边界条件集，这些条件将在不完美界面处强制执行。通过使用简单的微扰方法和谐波平衡法求解平面波入射时的散射问题。给出了任意波极化和入射角的示例结果。评估了非线性信号的相对大小及其在不完美界面无损评估中的潜在用途。特别要注意的是，在纵向临界角附近，由垂直剪切波激励的界面的非线性响应增强。开展这项研究的动机是需要开发无损方法来检测和定位具有粗大微观结构的金属中的小的、部分闭合的裂纹。
