Apparatus for detecting an abnormality such as a discontinuity in a predetermined region of a material by directing an elastic mechanical wave, such as an ultrasonic or other acoustic wave, in a series of pulses to portions of the region and providing response to the wave pulses reflected therefrom. The amplitudes of pulses reflected from a normal portion of the region may approximate the amplitudes of pulses reflected from a portion where an abnormality is present and thus make it difficult to distinguish between such portions. The directed wave is varied, as by rotating a transducer having an irregular cross-sectional radiation pattern, to provide randomlike variations in the shapes of successive pulses where reflected from a normal portion, differing detectably from any variations caused in the pulses where reflected from an abnormal portion. Means responsive to a plurality of successive reflected pulses are provided for effectively superimposing them, either electrically or in an overlaid visual display, the types of wave shapes of the superimposed pulses being indicative selectively of a normal or an abnormal portion of the region.
In an automatic ultrasonic testing method for automatically detecting an internal flaw of articles such as a solid-core station post insulator and a long-rod insulator in which ultrasonic noises are liable to be generated in ultrasonic testing waveform, use is made of a standard waveform having a plurality of maximum peak hold data in predetermined intervals at all the detecting points and obtained by detecting the normal article including the ultrasonic noises, with which ultrasonic testing waveforms of an article to be tested are compared. Therefore, it is possible to eliminate an instability of the ultrasonic testing waveform and to detect a flaw echo having a level lower than that of the ultrasonic noises.
A method of testing the integrity of the internal lining of a hollow body, especially a pipeline, by transmitting an ultrasonic wave from the exterior of the body through the adjacent wall of the body and monitoring the wave, if any, reflected from the opposite wall. In many cases, especially concrete linings, an intact or partially intact lining on the adjacent wall will absorb the ultrasonic wave and there is no reflected wave. A reflected wave frequently indicates loss of the lining on the adjacent wall although in some cases depending on, for example, the thickness of the lining or the material of which it is made, a reflected wave may be obtained even when the lining is intact. In such cases comparison of the reflected wave with predetermined standards provides an indication of whether or not the lining is intact.
A system for online monitoring the condition of a thermal barrier coating on the vanes and/or blades of a combustion turbine, or other forms of component deterioration affecting the acoustic properties of the vanes and/or blades. The system begins with a signal generator for transmitting a signal to an acoustic transmitter, and then to an acoustic waveguide secured within the turbine, adjacent to a vane. Acoustic waves passing through the vane's coating will have a certain magnitude and velocity when passing through an intact coating, which will change as the coating deteriorates. Additional variation of the acoustic wave will occur due to pressure pulses from passing blades, with the magnitude of the pressure pulses increasing as the blade's coating deteriorates. The acoustic waves are then received by a second acoustic waveguide. The resulting signal will be converted from an acoustic signal to an electrical signal by an acoustic receiver, and will pass through a filter to remove the lower frequency signals of the turbine from the higher frequency signals to be analyzed. The remaining higher frequency signals are sent to a computer, permitting the variations in the acoustic waves to be analyzed. A second embodiment relies solely on pressure pulses from passing blades to generate acoustic signals within the vanes.
The present invention is directed toward a method and apparatus for the ncontact inspection of workpieces having a plate-like portion of the first part joined via an inertia weld to the end of a second part extending away from the plate-like portion. The apparatus and method are particularly apt for the non-contact inspection of driver inflator igniter canisters for airbag applications, such canisters having a spool-shaped structure with outer walls which restrict access to the internal inertia welds for inspection. To achieve non-contact inspection, the invention comprises electromagnetic acoustic transducer means which generate a pulsed inspection signal and a detection signal. In one embodiment, the inspection signal comprises shear acoustic waves which are polarized parallel to the outer surface of the second member (e.g., the central web member of an inflator igniter canister), and a pulse/echo detection approach is employed. Separate electromagnetic acoustic transducer assemblies are utilized to generate the inspection and detection signals, with the transmit assembly being positioned between the detection assembly and workpiece.
An ultrasonic echo scanning apparatus having operator determined software controlled gated sampling of individual radio frequency excursions in the reflected ultrasonic energy waveform. Use of the system to obtain heretofore images of damage layers, resident in close physical proximity to large echo regions of a workpiece and images of good correlation with physical inspection of a disintegrated workpiece is also disclosed.
