Study on detectable size and depth of defects in noncontact acoustic inspection method
Study on detectable size and depth of defects in noncontact acoustic inspection method
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DOI：
10.7567/jjap.53.07kc15
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发表时间：
2014-07-01
影响因子：
1.5
通讯作者：
Utagawa, Noriyuki
中科院分区：
文献类型：
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作者：
Katakura, Kageyoshi;Akamatsu, Ryo;Utagawa, Noriyuki
研究了隧道、桥梁等大型结构的非接触检测方法。该方法涉及使用高功率声源和扫描激光多普勒振动计（SLDV）。在我们先前的研究中，我们提出了一个短纯音波的方法，以改善信号的信噪比（SNR）的测量结果。使用这种方法，检测到了使用我们以前的方法难以检测到的缺陷。在这项研究中，我们研究了可检测的大小和深度的缺陷，通过使用模型壁与圆形缺陷。声源与混凝土试件之间的距离为5m，并且在混凝土试件表面附近输出声压为约100dB。作为发送波，使用具有从500到7000 Hz的不同中心频率的短纯音波。同时还进行了常规的锤击法研究以进行比较，并确认了几乎相同的性能。从实验结果中，我们证实，弯曲共振频率检测成正比的圆形缺陷的深度，并与平面尺寸（面积）成反比，与解析结果一致的圆板。我们还发现，缺陷的振动能量表现出强烈的依赖于其深度。因此，可以期待使用共振频率和振动能量比来估计缺陷深度的可能性。将来可能会开发出一种实用的调查系统来取代锤击法。(C)2014日本应用物理学会
We study a noncontact inspection method for large-scale structures such as tunnels and bridges. This method involves the use of a high-powered sound source and a scanning laser Doppler vibrometer (SLDV). In our previous study, we proposed a tone burst wave method to improve the signal-to-noise ratio (SNR) of the measured result. Using this method, a defect that was difficult to detect using our previous method was detected. In this study, we examined the detectable size and depth of the defect by using a model wall with circular defects. The distance between the sound source and the concrete test piece was 5 m, and the output sound pressure was about 100 dB near the surface of the concrete test piece. As the transmitted wave, tone burst waves with different center frequencies from 500 to 7000 Hz were used. A conventional investigation by the hammer method was also simultaneously carried out for comparison and almost identical performance was confirmed. From the experimental result, we confirmed that the bending resonance frequency detected was proportional to the depth of the circular defect, and was in inverse proportion to the plane size (area) coincident to the analytical result for a circular plate. We also found that the vibration energy of the defect shows a strong dependency on its depth. Therefore, the possibility of defect depth estimation using the resonance frequency and the vibration energy ratio is expected. In the future, a practical investigation system that will replace the hammer method might be developed. (C) 2014 The Japan Society of Applied Physics