LASER ULTRASONICS FOR DETECTION OF ELASTIC NONLINEARITY USING COLLINEAR MIXING OF SURFACE ACOUSTIC WAVES
LASER ULTRASONICS FOR DETECTION OF ELASTIC NONLINEARITY USING COLLINEAR MIXING OF SURFACE ACOUSTIC WAVES
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DOI：
10.1063/1.3362406
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发表时间：
2010-02
期刊：
影响因子：
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通讯作者：
S. Sharples;T. Stratoudaki;R. Ellwood;I. Collison;M. Clark;M. Somekh
中科院分区：
文献类型：
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作者：
S. Sharples;T. Stratoudaki;R. Ellwood;I. Collison;M. Clark;M. Somekh
许多材料的固有材料非线性导致偏离胡克定律，因为弹性模量在施加应力下不是恒定的。在材料中传播的声波对弹性模量的变化敏感，并且这种敏感性可以用作固有材料非线性的度量。由于组件的静态应力在大多数情况下是不切实际的，因此本文探索的替代技术是使用大振幅表面声波（SAW）“泵”来产生沿样品表面沿着传播的应力。激光产生的高频猝发声表面波“探头”与泵共同传播，并在传播时受到相同的应力;应力将由泵的高度和探头相对于泵的相对位置决定，我们可以调整。这种共线混合导致探测波速度的微小变化，这是使用另一个激光器检测的。通过将速度的变化与所施加的应力相关联，可以获得材料的固有非线性的度量。我们提出了定量测量有关的材料特性，并讨论了其在损伤检测中的应用。
The inherent material nonlinearity of many materials leads to deviation from Hooke’s law, as the elastic moduli are not constant under applied stress. Acoustic waves traveling in the material are sensitive to changes in the elastic moduli, and this sensitivity can be used as a metric of intrinsic material nonlinearity. As static stressing of a component is in most cases impractical, an alternative technique, explored here, is to use a large amplitude surface acoustic wave (SAW) “pump” to generate stresses which propagate along the surface of a sample. A laser generated high frequency tone burst SAW “probe” is co‐propagated with the pump, and is subject to the same stress as it propagates; the stress will be determined by both the height of the pump and the relative position of the probe with respect to the pump, which we can adjust. This collinear mixing results in a small change in the velocity of the probe wave, which is detected using another laser. By relating the change of velocity to the applied stress, a measure of the material’s intrinsic nonlinearity can be obtained. We present quantitative measurements relating to material characterization, and implications for its use in damage detection are discussed.