可感測敲擊器之裂縫深度檢測精度探討

Accuracy of Crack Depth Measurement with New Impact Device

劉宗豪(Tzung-Hao Liou) ； 蕭家孟(Chia-Men Hsiao)

《先進工程學刊》 2卷2期 (2007/04) Pp. 89-94

https://doi.org/10.29948/JAE.200704.0004

摘要

以敲擊式繞射波傳動原理為基礎的混凝土表面裂縫檢測技術大多是以鑲嵌在小鋼棒之鋼珠敲擊混凝土表面導入應力波，再藉由放置在敲擊點附近的接收器啟動訊號擷取系統，該技術需要以間接方式反推真正鋼珠敲擊到混凝土表面之起始時間，無形中導入多種誤差。本研究以誤差傳播定理來探討各誤差因子之影響程度，結果顯示，第一接收器對點誤差嚴重影響裂縫深度量測值之準確率，隨著裂縫深度越淺，影響程度越高。應用可感測敲擊器記錄時間原點，可避免對點以及表面R波波速量測誤差，將可大幅提升檢測準確度。

關鍵字

裂縫深度檢測 ； 繞射波傳輸時間法 ； 非破壞性檢測

並列摘要

The time-of-flight diffraction technique for measuring the surface-opening crack depth is based on the use of transient stress waves which are introduced into the concrete by tapping a small steel sphere against a concrete surface. The data acquisition system is triggered by the receiver close to the impact point. The initial time of the impact can be calculated by known distance and surface wave speed. The disadvantage of this indirect way is that many errors may be involved in the calculation. In this study, theory of error propagation is utilized to investigate the influence of each parameter. The results indicate that the inaccurate position of the first receiver will result in large error of crack depth measurement. And the percentage error of crack depth will increase with the decreasing of crack depth. By using the impator with sensible device, the initial time of impact can be recorded directly without the influence of inaccurate position of first receiver or surface wave speed error. Therefore the accuracy of crack depth measurement can be greatly improved.

並列關鍵字

crack depth detection ； time-of-flight diffraction ； nondestructive testing