Ogi Hirotsugu, Sato Keiji, Asada Takeyasu, Hirao Masahiko
Graduate School of Engineering Science, Osaka University, Machikaneyama 1-3, Toyonaka, Osaka 560-8531, Japan.
J Acoust Soc Am. 2002 Dec;112(6):2553-7. doi: 10.1121/1.1512700.
This study is devoted to deducing exact elastic constants of an anisotropic solid material without using any advance information on the elastic constants by incorporating a displacement-distribution measurement into resonant ultrasound spectroscopy (RUS). The usual RUS method measures free-vibration resonance frequencies of a solid and compares them with calculations to find the most suitable set of elastic constants by an inverse calculation. This comparison requires mode identification for the measured resonance frequencies, which has been difficult and never been free from ambiguity. This study then adopts a laser-Doppler interferometer to measure the displacement-distribution patterns on a surface of the vibrating specimen mounted on pinducers; comparison of the measured displacement distributions with those computed permits us to correctly identify the measured resonance frequencies, leading to unmistakable determination of elastic constants. Because the displacement patterns are hardly affected by the elastic constants, an exact answer is surely obtained even when unreasonable elastic constants are used as initial guesses at the beginning of the inverse calculation. The usefulness of the present technique is demonstrated with an aluminum alloy and a langasite crystal.
本研究致力于通过将位移分布测量纳入共振超声光谱法（RUS），在不使用任何关于弹性常数的先验信息的情况下，推导出各向异性固体材料的精确弹性常数。通常的RUS方法测量固体的自由振动共振频率，并将其与计算结果进行比较，通过反演计算找到最合适的弹性常数集。这种比较需要对测量的共振频率进行模式识别，而这一直很困难且从未摆脱过模糊性。本研究随后采用激光多普勒干涉仪来测量安装在压电换能器上的振动试样表面的位移分布模式；将测量的位移分布与计算得到的位移分布进行比较，使我们能够正确识别测量的共振频率，从而明确无误地确定弹性常数。由于位移模式几乎不受弹性常数的影响，即使在反演计算开始时将不合理的弹性常数用作初始猜测，也肯定能得到准确答案。用铝合金和硅酸镓镧晶体证明了本技术 的实用性。
