Lamb wave generation using nanosecond laser ablation to detect damage
Lamb wave generation using nanosecond laser ablation to detect damage
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DOI：
10.1177/1077546316687904
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发表时间：
2018-12-01
影响因子：
2.8
通讯作者：
Yoshinaga, Atsushi
中科院分区：
文献类型：
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作者：
Hosoya, Naoki;Umino, Ryosuke;Yoshinaga, Atsushi
提出了一种基于激光烧蚀产生兰姆波的非接触损伤检测方法。以前，兰姆波产生的接触型传感器，如声发射或压电锆钛酸盐设备已被研究，以检测损坏。兰姆波发生系统具有嵌入到待检测目标结构的接触式激励装置，可以快速实现对诸如飞行器的巨大物体的大面积损伤检测。然而，在兰姆波发生系统中，用非接触式设备代替接触式设备，系统将具有足够的潜力在特定条件下激发，例如浸没在液体和高温物质中的目标结构。从测量中的信噪比的观点来看，具有比由常规激光热弹性产生的兰姆波产生的振幅大几百倍的振幅的LA产生的兰姆波是有利的。当激光能量密度达到10（12）-10（14）W/m（2）时，产生了LA区，这比激光热弹区的能量密度大。LA产生的Lamb波的振幅可能高于激光热弹性产生的Lamb波的振幅，这在假设的范围内。由于LA过程涉及许多非线性过程，如熔化，蒸发和升华，因此确认LA可以产生兰姆波及其模式是很重要的。在本文中，Lamb波，包含超过几百kHz的宽带频率元素产生的非接触脉冲激励使用LA，这是常见的振动测试中的高频范围内，激光喷丸，推进的微型飞机，螺栓松动诊断，等本方法进行评估，通过比较测量和计算的传播相位和群速度的Lamb波。此外，我们的方法的可行性证明了非接触损伤检测对2024铝合金板的裂纹。
This paper proposes a non-contact damage detection method based on Lamb waves generated by laser ablation (LA). Previously, Lamb waves generated by contact-type sensors such as acoustic emission or piezoelectric zirconate titanate devices have been studied to detect damage. Lamb wave generation systems with embedded contact-type excitation devices to objective structures to be inspected may quickly realize large-area damage detection on a huge object such as an aircraft. However, replacing contact-type devices with non-contact devices in Lamb wave generation systems, the systems will have sufficient potential to excite under the specific conditions such as submerged target structures in liquid and high-temperature substances. The LA-generated Lamb waves that have amplitudes several hundred times larger than those generated by conventional laser-thermoelastically generated Lamb waves are of advantage from the viewpoint of the signal-to-noise ratio in the measurements. When the laser fluence reaches 10(12)-10(14) W/m(2), which is greater than that for laser-thermoelastic regime, a LA regime is induced. The amplitudes of the LA-generated Lamb waves might be higher than those of the laser-thermoelastically generated Lamb waves; this is within the scope of the assumption. Since the LA process entails a number of nonlinear processes such as melting, vaporization, and sublimation, it is important to confirm that LA could generate a Lamb wave and its mode. In this paper, Lamb waves that contain broadband frequency elements of more than several hundred kHz are generated by non-contact impulse excitation using LA, which is common in vibration tests in the high-frequency range, laser peening, propulsion of micro-aircraft, bolt loosening diagnosis, etc. The present method is evaluated by comparing the measured and calculated propagation phase and group velocities of the Lamb waves. Furthermore, the feasibility of our approach is demonstrated by non-contact damage detection against an aluminum alloy 2024 plate with a crack.