Ryzy Martin, Grabec Tomáš, Sedlák Petr, Veres István A
Research Center for Non-Destructive Testing GmbH, Altenberger Strasse 69, 4040 Linz, Austria.
Nuclear Physics Institute, Czech Academy of Sciences, Řež 130, 25068 Řež, Czech Republic.
J Acoust Soc Am. 2018 Jan;143(1):219. doi: 10.1121/1.5020785.
The influence of a polycrystals' grain structure on elastic wave scattering is studied with analytical and numerical methods in a broad frequency range. A semi-analytical attenuation model, based on an established scattering theory, is presented. This technique accurately accounts for the grain morphology without prior assumptions on grain statistics. This is achieved by incorporating a samples' exact spatial two-point correlation function into the theory. The approach is verified by using a finite element method (FEM) to simulate P-wave propagation in 3D Voronoi crystals with equal mean grain diameter, but different grain shape uniformity. Aluminum and Inconel serve as representatives for weak and strong scattering cubic class materials for simulations and analytical calculations. It was found that the shape of the grains has a strong influence on the attenuation curve progression in the Rayleigh-stochastic transition region, which was attributed to mode conversion scattering. Comparisons between simulations and theory show excellent agreement for both materials. This demonstrates the need for accurately taking the microstructure of heterogeneous materials into account, to get precise analytical predictions for their scattering behaviour. It also demonstrates the impressive accuracy and flexibility of the scattering theory which was used.
采用解析和数值方法在宽频范围内研究了多晶体的晶粒结构对弹性波散射的影响。基于已建立的散射理论，提出了一种半解析衰减模型。该技术无需对晶粒统计进行先验假设就能准确考虑晶粒形态。这是通过将样品的精确空间两点相关函数纳入理论来实现的。通过使用有限元方法（FEM）模拟具有相等平均晶粒直径但不同晶粒形状均匀性的三维Voronoi晶体中的P波传播，对该方法进行了验证。铝和因科镍合金分别作为弱散射和强散射立方类材料的代表用于模拟和解析计算。研究发现，晶粒形状对瑞利 - 随机过渡区的衰减曲线进展有很大影响，这归因于模式转换散射。模拟与理论之间的比较表明，两种材料的结果都具有极好的一致性。这表明需要准确考虑异质材料的微观结构，以便对其散射行为获得精确的解析预测。这也证明了所使用的散射理论具有令人印象深刻的准确性和灵活性。
