Title of dissertation: DISTRIBUTED SENSING FOR FLEXIBLE STRUCTURES USING A FIBER OPTIC SENSOR SYSTEM Christopher S. Baldwin, Doctor of Philosophy, 2003 Dissertation directed by: Assistant Professor Steven Buckley Department of Mechanical Engineering In this dissertation, a framework is developed and demonstrated for the use of a new shape measurement system consisting of fiber Bragg grating (FB...

Non-destructive testing (NDT) is an important area of research, dealing with diagnostic and monitoring the health of structures and structural components and preventing catastrophic failures. One of the recently developed NDT techniques is the method of strain energy mode shapes that allows the determination of changes in structural integrity from changes in the vibrational response of a struct...

The spectral, interferometric, and polarization properties of mode-coupling fiber gratings under strain are described. The grating is formed by photosensitivity that uses modal interference in the two-mode fiber. Theoretical and experimental results show the possibilities of using the fiber grating for optical switches, tunable filters, interferometric sensors, and polarizers.

In this research, the modal parameters of a beam in free-free condition are extracted by performing different experiments in laboratory. For this purpose, two different techniques are employed. The first methodology is considered as a time domain method in Operational Modal Analysis. While the other one is frequency domain impact hammer test which is categorized as an Experimental Modal Analysi...

Elastic strain, electrical bias, and localized geometric deformations were applied to elliptical whispering-gallery-mode resonators fabricated with lithium niobate. The resultant perturbation of the mode spectrum is highly dependant on the modal indices, resulting in a discretely reconfigurable optical spectrum. Breaking of the spatial degeneracy of the whispering-gallery modes due to perturbat...

In this paper, modal analysis is carried out by using a Frenet frame-based shape measurement algorithm. This algorithm is validated through experiments conducted with a long slender, aluminum cantilever structure (65.625′′×2.0′′×0.125′′), which is instrumented with eight serially multiplexed fiber Bragg grating (FBG) sensors. The multiplexed FBG sensors measure the bending strain distribution a...

the brass tubes with foam cores of alsi7sic3, alsi7sic3fe1 and alsi7sic3fe3 were produced as the crush-boxes with circle and square cross-section. then axial compressive behavior and energy absorption capability of the foam-filled tubes were investigated during the quasi-static progressive plastic buckling. the uniaxial compressive stress–strain curves of the foam-filled brass tubes exhibited t...