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

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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