Sokolovskaya Yu G, Podymova N B, Karabutov A A
Faculty of Physics, M.V. Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia.
Faculty of Physics, M.V. Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia.
Ultrasonics. 2019 May;95:37-44. doi: 10.1016/j.ultras.2019.03.004. Epub 2019 Mar 5.
The aim of this work is to verify applicability of the Kramers-Kronig relations between the attenuation coefficient and phase velocity of longitudinal acoustic waves in carbon fiber reinforced plastic (CFRP) composites in a finite megahertz frequency range. To measure these characteristics, the method of broadband acoustic spectroscopy with a laser source of ultrasound is used. We have experimentally shown that absolute attenuation in CFRPs is determined by both absorption in a polymer matrix and scattering on carbon fibers and gas pores of several tenths of microns in size. We have also found that the increasing composite porosity leads to the decrease in the absolute value of the ultrasonic velocity and to the increase in its relative dispersion in the entire studied frequency range of 1-10 MHz. The experimental results have shown that for the studied CFRPs in this range, features of the mechanism causing attenuation and dispersion of longitudinal acoustic waves by propagation in composites do not influence on applicability of the local Kramers-Kronig relations.
这项工作的目的是验证在有限的兆赫兹频率范围内，纵向声波在碳纤维增强塑料（CFRP）复合材料中的衰减系数与相速度之间的克拉默斯-克勒尼希关系的适用性。为了测量这些特性，采用了带有超声激光源的宽带声学光谱法。我们通过实验表明，CFRP中的绝对衰减由聚合物基体中的吸收以及碳纤维和尺寸为十分之几微米的气孔上的散射共同决定。我们还发现，在整个1 - 10 MHz的研究频率范围内，复合材料孔隙率的增加会导致超声速度绝对值的降低以及其相对色散的增加。实验结果表明，对于该范围内所研究的CFRP，纵向声波在复合材料中传播时引起衰减和色散的机制特性并不影响局部克拉默斯-克勒尼希关系的适用性。
