Abstract: A system includes at least one optical fiber having at least one FBG and a detection system. The optical fiber is configured to be coupled to a structure in at least one location. The location at which the optical fiber is to be coupled to the structure is different from a location at which the FBG is disposed. The detection system includes a light source configured to inject light into the optical fiber, a photodetector configured to detect a shift in a wavelength spectrum of light reflected by the FBG as a result of a time-varying strain induced at the at least one FBG, and a processor configured to detect a shear-horizontal guided stress wave propagating in said structure based on the shift in the wavelength spectrum detected by the photodetector induced by a longitudinal-type guided stress wave that is propagated along the optical fiber.

Abstract: A system includes at least one circumferentially-polarized d15 shear ring transducer and a controller electrically coupled to the at least one circumferentially-polarized d15 shear ring transducer. The at least one circumferentially-polarized d15 shear ring transducer is configured to be disposed on a structure and to detect at least one shear horizontal-type acoustic emission from damage to the structure. The controller includes a machine-readable storage medium and a processor in signal communication with the machine-readable storage medium. The processor is configured to store acoustic emission signal data in the machine-readable storage medium when a signal amplitude detected by the at least one circumferentially-polarized d15 shear ring transducer crosses a first threshold.

Abstract: A system includes at least one optical fiber having at least one FBG and a detection system. The optical fiber is configured to be coupled to a structure in at least one location. The location at which the optical fiber is to be coupled to the structure is different from a location at which the FBG is disposed. The detection system includes a light source configured to inject light into the optical fiber, a photodetector configured to detect a shift in a wavelength spectrum of light reflected by the FBG as a result of a time-varying strain induced at the at least one FBG, and a processor configured to detect a shear-horizontal guided stress wave propagating in said structure based on the shift in the wavelength spectrum detected by the photodetector induced by a longitudinal-type guided stress wave that is propagated along the optical fiber.

Abstract: A system for detecting ice accretion includes a probe body, at least one magnetostrictive guided wave sensor for generating and receiving shear horizontal-type guided waves supported by said probe body, and a controller. The magnetostrictive guided wave sensor includes a ferromagnetic strip, at least one sensor coil disposed adjacent to said ferromagnetic strip, and at least one biasing magnet configured to induce a biasing magnetic field in said ferromagnetic strip. The controller includes a processor in signal communication with the at least one magnetostrictive guided wave sensor. The processor configured to cause the at least one magnetostrictive guided wave sensor to generate guided waves in the body, extract at least one signal feature from a guided wave signal received by the at least one magnetostrictive guided wave sensor, and determine at least one characteristic of ice accreted on an outer surface of said probe body.

Abstract: A system includes at least one circumferentially-polarized d15 shear ring transducer and a controller electrically coupled to the at least one circumferentially-polarized d15 shear ring transducer. The at least one circumferentially-polarized d15 shear ring transducer is configured to be disposed on a structure and to detect at least one shear horizontal-type acoustic emission from damage to the structure. The controller includes a machine-readable storage medium and a processor in signal communication with the machine-readable storage medium. The processor is configured to store acoustic emission signal data in the machine-readable storage medium when a signal amplitude detected by the at least one circumferentially-polarized d15 shear ring transducer crosses a first threshold.

Abstract: A system for detecting ice accretion includes a probe body, at least one magnetostrictive guided wave sensor for generating and receiving shear horizontal-type guided waves supported by said probe body, and a controller. The magnetostrictive guided wave sensor includes a ferromagnetic strip, at least one sensor coil disposed adjacent to said ferromagnetic strip, and at least one biasing magnet configured to induce a biasing magnetic field in said ferromagnetic strip. The controller includes a processor in signal communication with the at least one magnetostrictive guided wave sensor. The processor configured to cause the at least one magnetostrictive guided wave sensor to generate guided waves in the body, extract at least one signal feature from a guided wave signal received by the at least one magnetostrictive guided wave sensor, and determine at least one characteristic of ice accreted on an outer surface of said probe body.

Abstract: A method of inspecting a structure is disclosed. The method generally comprises selecting a search region of a dispersion curve of the structure corresponding to one or more inspection parameters. The search region comprises at least one guided wave mode activation point not located on the dispersion curve. The method further comprises activating, using an inspection system comprising at least one transducer, a plurality of activation points located within the search region of the dispersion curve and identifying an optimal activation point for the one or more inspection parameters. The optimal activation point comprises at least one of the plurality of activation points producing an optimal response for the one or more inspection parameters.

Abstract: A method of inspecting a structure is disclosed. The method generally comprises selecting a search region of a dispersion curve of the structure corresponding to one or more inspection parameters. The search region comprises at least one guided wave mode activation point not located on the dispersion curve. The method further comprises activating, using an inspection system comprising at least one transducer, a plurality of activation points located within the search region of the dispersion curve and identifying an optimal activation point for the one or more inspection parameters. The optimal activation point comprises at least one of the plurality of activation points producing an optimal response for the one or more inspection parameters.