Imaging Flaws in Thin Metal Plates Using a Magneto-Optic Device

Fatigue Crack Characterization in Conducting Sheets by Non Contact Stimulation of Resonant Modes

“…Previous research has shown low frequency resonant modal analysis to be a promising technique for the characterization of fatigue cracks in thin metal plates [2,3]. The technique provides the ability to quantify fatigue crack characteristics by monitoring the resonant frequency of free standing vibrational modes.…”

Multi-mode excitation and data reduction for fatigue crack characterization in conducting plates

“…The details of the experimental conditions can be found in [3]. Previous work has focused on monitoring a single resonance mode in order to determine the structural integrity of the test piece [1][2][3]. Using this approach, careful control must be exercised on the application of boundary conditions.…”

“…The frequency difference between these two modes was used in an attempt to remove boundary condition dependence from the test results. methods [1][2], is portable and completely noncontacting. In this paper we have fully described the operating principle of the device and performed a detailed examination of the frequency dependence of the generated force.…”

“…Resonant modal analysis has been shown to be a viable technique for fatigue crack characterization in thin plates [1,2]. Recent advances have improved the applicability of the technique through the use of a non-contact source as a means of inducing resonant vibrations in conducting sheets [3].…”

“…The cross product of (4) therefore produces a force normal to the surface of the sample. Previous research has shown that flaws are most visible when the forcing function induces a torque across the centerline of the electromagnet [1]. The poles of the permanent magnets are therefore situated such that the force under each pole would be in opposite directions.…”