The Use of Fibre Optic Sensors for Damage Detection and Location in Structural Materials
The Use of Fibre Optic Sensors for Damage Detection and Location in Structural Materials
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使用光纤传感器进行结构材料的损伤检测和定位
DOI：
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发表时间：
2004
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通讯作者：
B. Culshaw
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作者：
G. Thursby;B. Sorazu;D. Betz;M. Staszewski;B. Culshaw
测量超声兰姆波在结构材料中传播时的特性变化，经常被提出作为一种检测损伤的方法。在本文中，我们描述的工作，使用光纤传感器来检测兰姆波，并表明，这些传感器的方向特性，使我们不仅可以检测到损坏，但也定位it.We看看两种类型的光纤传感器，偏振传感器和光纤布拉格光栅。偏振传感器测量超声波作用于光纤的压力波引起的光纤双折射的变化。这是一种集成传感器，因为与样品结合的光纤长度需要大于超声波波长，以获得所需的灵敏度。该传感器的最大灵敏度是当光纤垂直于波传播方向定位时。光纤布拉格光栅本质上是点传感器，因为光栅长度需要是超声波波长的一部分，以获得最大的灵敏度。超声主要通过其产生的面内应变来检测，因此当光栅平行于波传播方向对齐时产生最大灵敏度。通过检查透射的兰姆波的变化或通过检测孔产生的反射，可以使用两种类型的传感器来检测钻到样品板中的孔。示出的技术的灵敏度由声源，孔和传感器的相对位置来确定。如果我们使用玫瑰花状配置的光纤布拉格光栅（即，形成等边三角形的3个光栅），则可以使用光栅的方向灵敏度来确定兰姆波的方向。使用两个这样的方向可以让我们从其中两个方向的交点计算出波的来源。如果波的源是洞（它充当被动源），那么可以确定该洞的位置。
The measurement of changes in the properties of ultrasonic Lamb waves propagating through structural material has frequently been proposed as a method for the detection of damage. In this paper we describe work that uses optical fibre sensors to detect the Lamb waves and show that the directional properties of these sensors allow us to not only detect damage, but also to locate it. We look at two types of optical fibre sensor, a polarimetric sensor and the fibre Bragg grating. The polarimetric sensor measures the change in birefringence of a fibre caused by the pressure wave of the ultrasound acting upon it. This is an integrated sensor since the fibre length bonded to the sample needs to be greater than the ultrasonic wavelength in order to obtain the required sensitivity. The maximum sensitivity of this sensor is when the fibre is positioned normal to the direction of wave propagation. Fibre Bragg gratings are essentially point sensors since the grating length needs to be a fraction of the ultrasound wavelength to obtain maximum sensitivity. Ultrasound is detected mainly through the in-plane strain it produces and maximum sensitivity is therefore produced when the grating is aligned parallel to the direction of wave propagation. Holes drilled into sample plates can be detected using both type of sensor by examining the changes in either the transmitted Lamb wave or through detection of the reflections produced by the hole. The sensitivity of the technique is shown to be determined by the relative positions of the acoustic source, the hole and the sensor. If we use fibre Bragg gratings in a rosette configuration (i.e. 3 gratings forming an equilateral triangle) then the direction of the Lamb wave can be determined using the directional sensitivities of the gratings. Using two such rosettes allows us to calculate the source of the wave from the intersection of two of these directions. If the source of the wave is the hole (which acts as a passive source), then the location of that hole can be determined.