A new method for measuring the structure and strength of anisotropic composite material using ultrasonic waves

由于超声波是一种机械振动，因此通过材料传播的超声波响应可以用来表征材料的机械和结构特性。超声传播的空间分析给出了材料的结构信息。声速的测量决定了弹性常数。然而，超声信号通过具有微结构的各向异性材料时，与入射波相比，通常会发生变形，且较为复杂。这使得分析相当困难。本研究分析了超声波在各向异性材料中的行为。提出了测量各向异性材料强度并获取构造信息的方法。首先，利用超声传播的简化模型求出其声场。该模型由一系列间隔和直径恒定的平行圆柱体组成。辐射波在柱体表面发生散射，散射波在柱体表面形成二次入射波。通过圆柱间的多径传播函数计算得到的声场。实验采用直径为2mm ~ 3mm，间隔为2.5 mm ~ 7mm的丙烯酸圆柱制成的单轴各向异性材料。当相邻圆柱间距大于两倍波长时，实验结果与理论结果一致。然后，预测了单轴各向异性材料的空间参数。利用二维衍射光栅模型，在频域对散射声场进行了分析。在许多方向上接收到的散射波的比较给出了材料中圆柱体的直径和间隔。计算值与实验值吻合较好。作为一种医学诊断方法，需要对柱体直径和间距进行估计。在旋转各向异性材料时，检测接收波。当各向异性材料的圆柱体方向与超声波入射方向重合时，接收到的信号随散射角的变化很大。这一性质对探测各向异性材料的方向是有用的。少

Since ultrasonic wave is a mechanical vibration, the ultrasonic responses propagating through a material can be used to characterize its mechanical and structural properties. The spatial analysis of ultrasonic propagation gives the structural information of the material. The measurement of sound velocity decides the elastic constants. However, the ultrasonic signal passed through anisotropic material with micro structure generally deforms and is complicate compared to the incident wave. It makes the analysis quite difficult.In this study, the behavior of ultrasonic wave in anisotropic material is analyzed. The procedure to measure the strength of anisotropic material and obtain the constructive information is proposed.First, the ultrasonic wave propagated through a simplified model is used to find its sound field. This model is consisted of a series of parallel cylinders with a constant interval and diameter. The radiated wave scatters on the surface of cylinders and the scattered wave … More s become secondary incident waves to other cylinders. The resulting sound field is calculated by the function of multi-path propagation among the cylinders. The experiment is performed by using a one-axis anisotropic material made from acrylic cylinders with 2 mm to 3 mm diameter and 2.5 mm to 7 mm interval. When the interval of the neighboring cylinders is larger than twice of the wavelength, the experimental results and theoretical results are agreed.Then, the spatial parameters of the one-axis anisotropic material are predicted. Using 2-dimension diffraction grating model, the scattered sound field is analyzed in frequency domain. The comparison of the scattered waves received in many directions gives the diameter and interval of the cylinders in the material. The calculated values are coincident with the experimental values. The estimation of diameter and interval of the cylinder is required as a medical diagnosing method.While rotating the anisotropic material, the received wave is detected. When the direction of cylinder in the anisotropic material coincides with the incident direction of ultrasonic wave, the received signals vary largely as a function of the scattering angle. This property is useful to detect the direction of anisotropic material. Less