Vibrothermography is a technique for finding cracks and delaminations through infrared imaging of vibration-induced heating. While vibrothermography has shown remarkable promise, it has been plagued by persistent questions about its reproducibility and reliability. Fundamentally, the crack heating is caused by the vibration, and therefore to understand the heating process we must first understand the vibration process. We lay out the problem and begin the first steps toward relating

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... y to the local motion around a crack as well as the crack size. A particular mode, the third-order free-free flexural resonance, turns out to be particularly insensitive to the presence of clamping and transducer contact. When this mode is excited in a simple bar geometry the motions of the part follow theoretical calculations quite closely, and a single point laser vibrometer measurement is sufficient to evaluate the motion everywhere. Simple calculations estimate stress and strain anywhere in the bar, and these can then be related to observed crack heating. A wireless handheld probe with spectrally constrained evolution strategies for diffuse optical imaging of tissue Rev. Sci. Instrum. 83, 033108 (2012) In vivo and simultaneous multimodal imaging: Integrated multiplex coherent anti-Stokes Raman scattering and two-photon microscopy Appl. Phys. Lett. 97, 223702 (2010) Suitability of using far-infrared imaging system for noncontact evaluation on working state of implantable medical devices J. Appl. Phys. 105, 064701 (2009) Real-time three-dimensional optoacoustic imaging using an acoustic lens system Appl. Phys. Lett. 85, 846 (2004) Noninvasive, low-noise, fast imaging of blood volume and deoxygenation changes in muscles using light-emitting diode continuous-wave imager Rev. Sci. Instrum. 73, 3065 (2002) Additional information on AIP Conf. Proc. ABSTRACT. Vibrothermography is a technique for finding cracks and delaminations through infrared imaging of vibration-induced heating. While vibrothermography has shown remarkable promise, it has been plagued by persistent questions about its reproducibility and reliability. Fundamentally, the crack heating is caused by the vibration, and therefore to understand the heating process we must first understand the vibration process. We lay out the problem and begin the first steps toward relating detectability to the local motion around a crack as well as the crack size. A particular mode, the third-order free-free flexural resonance, turns out to be particularly insensitive to the presence of clamping and transducer contact. When this mode is excited in a simple bar geometry the motions of the part follow theoretical calculations quite closely, and a single point laser vibrometer measurement is sufficient to evaluate the motion everywhere. Simple calculations estimate stress and strain anywhere in the bar, and these can then be related to observed crack heating.