彈性波在溝槽尖端之繞射分析

The Diffraction of Elactic Waves on the Tip of Slot

盧樹人(Shu-Jen Lu)

指導教授 ： 何旭川

元智大學/工程學院/機械工程學系/碩士(1996年)

摘要

彈性波在裂縫尖端的繞射現象，以被廣泛應用於偵測材料或結構件內部的
缺陷如裂縫 ,空孔等 ,然在實驗室欲以人工方法製成真實裂縫不僅過程複
雜失敗率亦相當高．本文以放電加工方法製作寬0.3mm溝槽模擬真實裂縫
，探討彈性波在溝槽尖端之繞射效應，實驗方法為以鋼,鋁，銅三種不同
材質試塊，改變入射角，頻率 ，觀察溝槽尖端在不同角度所接收的繞射
波強度，並與真實裂縫尖端繞射波強度之理論值相比，瞭解兩者差異，一
方面做為偵測結構件溝槽缺陷之參考，另一方面又可在無法製作真實裂縫
而以溝槽取代時，提供類比推導所需的實驗數據．

關鍵字

彈性波 ； 繞射 ； 溝槽尖端 ； 裂縫

並列摘要

The diffraction of elastic wave on the crack tip has been
extensively applied to detectthe internal defects such as
cracks, cavity in materials or structures. To produces thereal
crack, it is not only diffraction but also easy to fail. In this
investigation, awidth of 0.3mm solt made by electrical discharge
machining is presented to replace thereal crack. The diffraction
of elastic wave on the tip of slot has been studied for
thematerials of steel, aluminum and brass. In the experiment,
the amplitudes of diffractedwave are measured for the varied
receiving angles.incident wave are also included. The
experimental reasults of diffraction on the tip of slot are
compared with the theoretical results of real crack tip. By
exposing theirdifferences, one could distinguish the defect
between crack and slot. On the other hand,once the real crack is
not possible to produce, present results of slot may
provideapproximately experimental data for analogy.

並列關鍵字

elastic wave ； diffraction ； tip of slot ； crack