Abstract The detection and evaluation of closed cracks are of prime interest in industry. Whereas conventional ultrasonic methods fail to detect these defects, nonlinear methods based on activation of the nonlinear behavior of closed cracks constitute an interesting alternative. The aim of this article is to give a better understanding of interactions between cracks and a longitudinal elastic wave for a quantitative investigation into nonlinear signatures. Using a 1D approach based on the literature, the nonlinear signature of the contact interface is analyzed in two cases. In the first, the interface is initially open and in the second, it is initially closed before interaction with an elastic wave. These signatures were qualitatively observed experimentally in real cracks. Next, in order to investigate the influence of the coexistence of open and closed zones within the interface, a numerical 2D-study is proposed. Two configurations are considered involving two steel blocks in contact, with different contact interface morphologies. The first configuration is a perfectly plane contact interface, while the second one involves an interface between a concave surface and a plane surface. A non-plane wave is also considered. This study attempts to establish a link between local second harmonic generation and interface parameters (pre-stress, gap) that can be exploited for the nondestructive quantitative evaluation of interfaces or cracks.

中文翻译：

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接触界面形态对纵波与摩擦接触界面非线性相互作用的影响：数值研究

摘要 闭合裂纹的检测和评估是工业界的主要关注点。传统的超声波方法无法检测到这些缺陷，而基于激活闭合裂纹非线性行为的非线性方法构成了一种有趣的替代方法。本文的目的是更好地理解裂缝和纵向弹性波之间的相互作用，以便对非线性特征进行定量研究。使用基于文献的一维方法，在两种情况下分析接触界面的非线性特征。在第一个中，界面最初是开放的，在第二个中，它在与弹性波相互作用之前最初是关闭的。这些特征是在真实裂缝中通过实验定性观察到的。下一个，为了研究界面内开放和封闭区域共存的影响，提出了数值二维研究。考虑两种配置，涉及两个接触的钢块，具有不同的接触界面形态。第一种配置是完美的平面接触界面，而第二种配置涉及凹面和平面之间的界面。还考虑了非平面波。本研究试图建立局部二次谐波生成与界面参数（预应力、间隙）之间的联系，可用于对界面或裂纹进行无损定量评估。第一种配置是完美的平面接触界面，而第二种配置涉及凹面和平面之间的界面。还考虑了非平面波。本研究试图建立局部二次谐波生成与界面参数（预应力、间隙）之间的联系，可用于对界面或裂纹进行无损定量评估。第一种配置是完美的平面接触界面，而第二种配置涉及凹面和平面之间的界面。还考虑了非平面波。本研究试图建立局部二次谐波生成与界面参数（预应力、间隙）之间的联系，可用于对界面或裂纹进行无损定量评估。