Abstract:
A method for processing thermography signals. A time series of radiometric data is measured from a surface (104) of an object (102) over a period of heating and subsequent cooling, and a mathematical curve (1, 2) is fit to the data. An amplitude aspect and one or more shape aspects are identified for each curve. The amplitude and shape aspects are then used together to characterize features such as defects in the object. The amplitude and shape aspects for an array of such data may be combined in a single noise-free visual display (100) by associating hue (color) with the shape aspect and luminance (brightness) with the amplitude aspect. Optionally, a second shape aspect may be identified and associated with saturation on the display. A visible image of the object may be overlaid on the display.
Abstract:
A defect detection system (10) for thermally imaging a structure (12) that has been energized by a sound energy. The system (10) includes a transducer (14) that couples a sound signal into the structure (12), where the sound signal causes defects in the structure (12) to heat up. In one embodiment, the sound signal has one or more frequencies that are at or near an eigen-mode of the structure (12). In another embodiment, a non-linear coupling material (16) is positioned between the transducer (14) and the structure (12) to couple the sound energy from the transducer (14) to the structure (12). A predetermined force (26) is applied to the transducer (14) and a pulse duration and a pulse frequency of the sound signal are selected so t hat the sound energy induces acoustic chaos in the structure (12), thus generating increased thermal energy. A thermal imaging camera (22) images the structure (12) when it is heated by the sound signal.
Abstract:
A defect detection system (10) for thermally imaging a structure (12) that has been energized by a sound energy. The system (10) includes a transducer (14) that couples a sound signal into the structure (12), where the sound signal causes defects in the structure (12) to heat up. In one embodiment, the sound signal has one or more frequencies that are at or near an eigen-mode of the structure (12). In another embodiment, a non-linear coupling material (16) is positioned between the transducer (14) and the structure (12) to couple the sound energy from the transducer (14) to the structure (12). A predetermined force (26) is applied to the transducer (14) and a pulse duration and a pulse frequency of the sound signal are selected so t hat the sound energy induces acoustic chaos in the structure (12), thus generating increased thermal energy. A thermal imaging camera (22) images the structure (12) when it is heated by the sound signal.
Abstract:
A method for processing thermography signals. A time series of radiometric data is measured from a surface (104) of an object (102) over a period of heating and subsequent cooling, and a mathematical curve (1, 2) is fit to the data. An amplitude aspect and one or more shape aspects are identified for each curve. The amplitude and shape aspects are then used together to characterize features such as defects in the object. The amplitude and shape aspects for an array of such data may be combined in a single noise-free visual display (100) by associating hue (color) with the shape aspect and luminance (brightness) with the amplitude aspect. Optionally, a second shape aspect may be identified and associated with saturation on the display. A visible image of the object may be overlaid on the display.
Abstract:
A hand-held thermography system (8). A generator (10) supplies current to a transformer (15) in a handle (16). An induction coil (20) connected to the transformer (15) extends from the handle (16). The induction coil (20) induces eddy currents in a test object (50), producing a thermal topography on a surface (52) of the object (50) that reveals structural features including defects in the object. An infrared camera (24) mounted on the transformer (16) digitizes images of the thermal topography. A controller (12) processes the images, displays them on a monitor (14), and stores them in a digital memory (11) for evaluation. Digitized positional data relating the position of the image to the surface may also be stored. An operator (40) presses a trigger (17), signaling the controller (12) to start current to the induction coil (20) and simultaneously to acquire and process one or more images from the camera (24). The images may be evaluated visually and/or by computerized analysis techniques for analyzing defects in the object.
Abstract:
A thermal imaging system (80) for detecting cracks (100) and defects in a component (82). An electro-magnetic acoustic transducer (EMAT) (84) is coupled to the component (82), and introduces pulsed sound signals therein. The sound signals cause the defects (100) to heat up, and IR radiation (98) from the component (82) is detected by a thermal camera. The amplitude of the pulsed signals are substantially constant, and the frequency of the pulsed signal can be changed within each pulse. A control unit is employed to provide timing and control for the operation of the EMAT (84) and the camera.