超音波相位陣列技術在混凝土非破壞性檢測的應用

在超音波混凝土非破壞性檢測中，混凝土內部的礫石與孔隙會使高頻超音波能量受到強烈的散射與衰減，這些現象將會使得接收到的信號之訊噪比變得相當低，因此高頻超音波在混凝土結構成像的解析能力往往不佳。在本研究中將使用五顆頻率為100 kHz之低頻超音波探頭模擬相位陣列技術，藉由控制各探頭發射之時間延遲使能量在指定深度上聚焦以強化目標信號能量並提升混凝土成像之解析度。同時為了證實相位陣列技術是否能夠在混凝土環境下有效提升訊噪比，我們將比較單探頭掃描、合成孔徑聚焦技術、全聚焦法與相位陣列技術這四種方法在均質混凝土塊與兩塊在不同深度埋有空心鋼管之混凝土試體做底部與鋼管信號解析度之量化比較並探討各方法之優缺點。我們的研究結果顯示：(1)單探頭掃描成像與合成孔徑聚焦技術成像由於本身資料訊噪比過低以及資料的重合數不夠多而得到最差的成像結果。(2)全聚焦法成像因超音波能量傳達到深部時受到強烈衰減，因此深部鋼管信號的訊噪比將變得相當低，所以全聚焦法即使透過大量的資料重合也難以解析出深部的鋼管位置，但是對於能量受到較少衰減的淺部鋼管信號與強反射面的底部信號仍能透過大量的資料重合解析出來。(3)相位陣列技術成像受到相鄰探頭發出表面波而產生的陰影區影響，無法解析出埋在混凝土試體淺部的鋼管信號，但對於解析試體底部與深部的鋼管信號，相位陣列技術具有最佳的解析能力。

關鍵字

非破壞性檢測；混凝土；相位陣列

並列摘要

In ultrasonic non-destructive test of concrete, sands, aggregates and pores in the concrete component can cause the strong scattering and attenuation of the high-frequency ultrasound. These effects make a difficulty of using high-frequency ultrasound to test concrete structure. The non-destructive testing is evolving to the multi-source and multi-receiver techniques due to the fast progress in electronic and computing technologies. In this study, four techniques; B-scan which is a traditional single-probe pulse-echo method, synthetic aperture focusing technique (SAFT) which is a post-process method to refocus the diffracted energy in B-scan image, total focusing method (TFM) which is a post-process technique using the multi-receiver and phased array (PA) which is a multi-source and multi-receiver technique are used to test the concrete structure for the 100 kHz ultrasounds. Study results show that the B-scan technique and SAFT have the worst resolution because of the low signal to noise ratio (SNR) data and lack of stacking data. The performance of TFM depends on the data’s SNR and number of stacking, and there is no help for a low SNR data by this technique. Therefore, TFM cannot resolve the middle-depth steel-pipe (diameter 2.5 cm) where the ultrasonic energy diffracted from this steel-pipe is quite small but can result in a better image resolution of shallow-depth steel-pipe and bottom-wall of specimen where ultrasounds have better SNR. Phased array technique has the best resolution for the deep steel-pipe and bottom-wall of specimen except the shallow steel-pipe which its diffracted echoes are severely contaminated by the dead zone of adjacent transducers.

並列關鍵字

NON-DESTRUCTIVE TESTING ； PHASED ARRAY

參考文獻

[2] Breysse, Denys, Non-Destructive Assessment of Concrete Structures: Reliability and Limits of single and Conbined Techniques, London, 2012.

[3] Mori K., Spagnoli A., Murakami Y., Kondo G. and Torigoe I., “A New Non-Contacting Non-Destructive Testing Method for Defect Detection in Concrete,” NDT & E Int, Vol. 35, 2002, 399-406.

[6] Ohtsu M., Shigeishi M., Sakata Y., “Nondestructive Evaluation of Defects in Concrete by Quantitative Acoustic Emission and Ultrasonics,” Ultrasonics, Vol. 36, 1998, 187-195.

[7] Glenn W., Paul F., Benjamin A. G., Joseph L. M., “Ultrasonic Testing of Reactive Powder Concrete,” IEEE Trans. Ultrason. Ferr. Freq. Contr., Vol. 51, 2004, 193-201.

[8] Frank M.,“Phased Array for Ultrasonic Investigations in Concrete Components,” J Nondesrt Eval , Vol. 27, 2008, 23-33.

國際替代計量

超音波相位陣列技術在混凝土非破壞性檢測的應用

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