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首页> 外文期刊>Smart Materials & Structures >Geometry-independent attenuation and randomness of ultrasound wave propagation in concrete measured by embedded PZT transducers
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Geometry-independent attenuation and randomness of ultrasound wave propagation in concrete measured by embedded PZT transducers

机译：通过嵌入式PZT换能器测量混凝土中超声波传播的几何无关衰减和随机性

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摘要

Ultrasound is widely used in nondestructive testing (NDT). It is the basis of many NDT techniques, such as acoustic emission, phased array and synthetic aperture focusing technique. The attenuation of ultrasound is a key factor that ensures the feasibility of these techniques. Conventional studies of attenuation are mostly conducted in specimens that have dimensions smaller than ultrasound wavelengths. In this type of study, reflections from media boundaries interfere with the wave, resulting in a geometry-dependent attenuation that cannot be applied in another specimen with a different geometry, even if the material is identical. Another factor that impacts on the viability of ultrasound NDT techniques is the spatial uniformity of waves in the concrete sample. To serve as a reference in testing defects, the degree of randomness caused by the material's heterogeneity should be estimated in conditions free of defects. In this study, a large concrete specimen was fabricated to suppress boundary reflections of the wave, creating an environment less dependent on geometry. Twenty-two PZT (lead zirconate-titanate ceramics) transducers were arranged in a three-by-seven array to transmit and receive ultrasound waves. This experiment sought to measure attenuation over distance and by frequency, as well as analyzing attenuation factors such as geometrical spreading and material absorption. A quadratic trend with good consistency between attenuation and frequency was found, indicating minimal local attenuation. The degree of randomness in the wave was measured by three indices: amplitude, group velocity and the frequency spectrum cross-correlation factor. Frequency dispersion was also described using group velocity. The findings of this study can serve as a reference for other NDT research, disclosing geometry-independent attenuation and the variability of wave characteristics in concrete.
机译：超声波广泛用于非破坏性测试（NDT）。它是许多NDT技术的基础，例如声发射，分阶段阵列和合成孔径聚焦技术。超声波的衰减是确保这些技术的可行性的关键因素。衰减的常规研究主要是在具有小于超声波波长的尺寸的标本中进行的。在这种类型的研究中，来自媒体边界的反射干扰波，导致几何依赖性衰减，即使材料是相同的，也不能在具有不同几何形状的另一样本中施加的几何依赖性衰减。影响超声波NDT技术的可行性的另一个因素是混凝土样品中的波浪的空间均匀性。为了作为测试缺陷的参考，应在没有缺陷的条件下估算材料异质性引起的随机性程度。在这项研究中，制造了一个大的混凝土试样以抑制波的边界反射，从而越依赖几何形状。二十二个PZT（铅锆酯 - 钛酸酯陶瓷）换能器以三七七七阵列布置，以传输和接收超声波。该实验试图通过距离和频率测量衰减，以及分析几何扩展和材料吸收等衰减因子。发现了衰减和频率良好一致性的二次趋势，表明局部衰减最小。波浪中的随机性由三个指数测量：幅度，群体速度和频谱互相关因子。还使用组速度描述频率分散。该研究的发现可以作为其他NDT研究的参考，公开了与混凝土中的几何衰减和波动特性的变化。

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