Abstract: An apparatus for inspecting a railroad track may include a first sensor, a second sensor, and a controller. The first sensor may detect a first signal while the second sensor may detect a second signal. The first signal may correspond to a response of the railroad track, at a first location on the railroad track, to a motion of a rail car wheel on the railroad track. The second signal may correspond to the response of the railroad track, at a second location on the railroad track, to the motion of the rail car wheel on the railroad track. The controller may generate, based on the first signal and the second signal, a transfer function corresponding to the response of the railroad track at the second location to stimuli applied at the first location. Defects in the railroad track may be detected by analyzing the transfer function.

Abstract: An apparatus for inspecting a railroad track may include a first sensor, a second sensor, and a controller. The first sensor may detect a first signal while the second sensor may detect a second signal. The first signal may correspond to a response of the railroad track, at a first location on the railroad track, to a motion of a rail car wheel on the railroad track. The second signal may correspond to the response of the railroad track, at a second location on the railroad track, to the motion of the rail car wheel on the railroad track. The controller may generate, based on the first signal and the second signal, a transfer function corresponding to the response of the railroad track at the second location to stimuli applied at the first location. Defects in the railroad track may be detected by analyzing the transfer function.

Abstract: Methods and apparatus, including computer program products, are provided for nonlinear ultrasonic testing. In one aspect there is provided a method, which may include generating at least one ultrasonic wave to enable the at least one ultrasonic wave to propagate through a solid; detecting the at least one ultrasonic wave propagating through the solid; and determining a stress of the solid based on at least one of an imaginary component of a wavenumber, a wave amplitude, a wave strength, a statistical moment in a time domain, or a statistical moment in a frequency domain of the at least one ultrasonic wave.

Abstract: In some example implementations, there is provided a method. The method may include generating, by an air-coupled transducer, a first ultrasonic guided wave to cause the generated ultrasonic guided wave to propagate into a rail being tested for one or more defects, wherein a frequency of the first ultrasonic guided wave is controlled by at least changing the frequency of a voltage sent to the air-coupled transducer generating the first ultrasonic guided wave; receiving, by a receiver, a second ultrasonic guided wave, wherein the second ultrasonic guided wave is received from the rail; and analyzing a signal representative of the received second ultrasonic guided wave to detect the one or more defects in the rail. Related systems, methods, and articles of manufacture are also provided.

Abstract: Methods and apparatus, including computer program products, are provided for determining rail stress. The method may include generating at least one ultrasonic guided wave to enable the at least one ultrasonic guided wave to propagate through a rail; detecting at least one of a fundamental frequency component of the at least one ultrasonic guided wave, one or more harmonics of the at least one ultrasonic guided wave, and/or a mixing component of the at least one ultrasonic guided wave; and determining a stress of the rail based on at least a nonlinearity parameter determined from the detected at least one of the fundamental frequency component, the one or more harmonics, and the mixing component. Related apparatus, systems, methods, and articles are also described.

Abstract: Methods and apparatus, including computer program products, are provided for nonlinear ultrasonic testing. In one aspect there is provided a method, which may include generating at least one ultrasonic wave to enable the at least one ultrasonic wave to propagate through a solid; detecting the at least one ultrasonic wave propagating through the solid; and determining a stress of the solid based on at least one of an imaginary component of a wavenumber, a wave amplitude, a wave strength, a statistical moment in a time domain, or a statistical moment in a frequency domain of the at least one ultrasonic wave.

Abstract: In some example implementations, there is provided a method. The method may include generating, by an air-coupled transducer, a first ultrasonic guided wave to cause the generated ultrasonic guided wave to propagate into a rail being tested for one or more defects, wherein a frequency of the first ultrasonic guided wave is controlled by at least changing the frequency of a voltage sent to the air-coupled transducer generating the first ultrasonic guided wave; receiving, by a receiver, a second ultrasonic guided wave, wherein the second ultrasonic guided wave is received from the rail; and analyzing a signal representative of the received second ultrasonic guided wave to detect the one or more defects in the rail. Related systems, methods, and articles of manufacture are also provided.

Abstract: Methods and apparatus, including computer program products, are provided for determining rail stress. The method may include generating at least one ultrasonic guided wave to enable the at least one ultrasonic guided wave to propagate through a rail; detecting at least one of a fundamental frequency component of the at least one ultrasonic guided wave, one or more harmonics of the at least one ultrasonic guided wave, and/or a mixing component of the at least one ultrasonic guided wave; and determining a stress of the rail based on at least a nonlinearity parameter determined from the detected at least one of the fundamental frequency component, the one or more harmonics, and the mixing component. Related apparatus, systems, methods, and articles are also described.

Abstract: Disclosed are systems, methods and articles, including an inspection system that includes at least one generator to apply energy to an object at an application point to cause waves to travel, at least partly, through the object. The system further includes at least one detector configured to detect at least a portion of the waves traveling through the object, and a statistical analyzer to perform a statistical analysis based on an output produced by the at least one detector in response to the detected portion of the waves, the statistical analysis being used to determine whether at least one defect is present in the object.

Abstract: Disclosed are systems, methods and articles, including an inspection system that includes at least one generator to apply energy to an object at an application point to cause waves to travel, at least partly, through the object. The system further includes at least one detector configured to detect at least a portion of the waves traveling through the object, and a statistical analyzer to perform a statistical analysis based on an output produced by the at least one detector in response to the detected portion of the waves, the statistical analysis being used to determine whether at least one defect is present in the object.