Background: Structural response measurements are challenging in aerodynamic testing environments due to high-speed requirements, facility vibrations, and the desire for non-intrusive measurements. Objective: This study uses stereo digital image correlation (DIC) to investigate the response of a jointed beam under aerodynamic loading in a shock tube. Methods: The incident shock subjects the beam to an impulsive frontal load followed by periodic transverse loading from vortex shedding. Several considerations necessary to realize high-precision are addressed: first, a hybrid stereo camera calibration accounted for tangential distortions when imaging through thick windows. Second, a measurement bias from Xenon flash-lamp light sources was identified and removed using laser illumination. Third, facility motion was mitigated by vibration isolation and appropriate signal filtering. Finally, aero-optical distortions from turbulence were removed using a low-order reconstruction. Results: The resulting displacement data has a noise floor of approximately ± 1 μm at 20 kHz sampling rate. The reduction of primary noise sources allows a transient structural response on the order of 10–40 μm to be quantified. The highest vibrations occurred when the vortex shedding frequency matched the beam’s natural frequency. Conclusion: the noise reduction techniques described allow for structural measurements requiring high-precision, non-intrusive displacement data to be performed in aerodynamic environments.

中文翻译：

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用于研究激波管中流体-结构相互作用的高精度数字图像相关性

背景：由于高速要求、设施振动和非侵入式测量的需求，结构响应测量在空气动力学测试环境中具有挑战性。目的：本研究使用立体数字图像相关 (DIC) 来研究连接梁在激波管中气动载荷下的响应。方法：入射冲击使梁承受脉冲正面载荷，然后是来自涡旋脱落的周期性横向载荷。解决了实现高精度所需的几个考虑因素：首先，混合立体相机校准解决了通过厚窗成像时的切向失真。其次，使用激光照明识别并消除氙气闪光灯光源的测量偏差。第三，通过隔振和适当的信号过滤减轻了设施运动。最后，使用低阶重建消除了湍流的气动光学失真。结果：在 20 kHz 采样率下，所得位移数据的本底噪声约为 ± 1 μm。主要噪声源的减少允许量化 10–40 μm 数量级的瞬态结构响应。当涡旋脱落频率与梁的固有频率相匹配时，发生最高振动。结论：所描述的降噪技术允许在空气动力学环境中执行需要高精度、非侵入性位移数据的结构测量。所得位移数据在 20 kHz 采样率下的本底噪声约为 ± 1 μm。主要噪声源的减少允许量化 10–40 μm 数量级的瞬态结构响应。当涡旋脱落频率与梁的固有频率相匹配时，发生最高振动。结论：所描述的降噪技术允许在空气动力学环境中执行需要高精度、非侵入性位移数据的结构测量。所得位移数据在 20 kHz 采样率下的本底噪声约为 ± 1 μm。主要噪声源的减少允许量化 10–40 μm 数量级的瞬态结构响应。当涡旋脱落频率与梁的固有频率相匹配时，发生最高振动。结论：所描述的降噪技术允许在空气动力学环境中执行需要高精度、非侵入性位移数据的结构测量。