BACKGROUND

Devices using ultrasonic guided waves (USGW) have been increasing in importance as a means for inspecting structures, such as plates, pipes and shells that may be comprised of multiple layers of distinct materials. Every USGW inspection system design involves selection of operating points that include a collection of parameters, such as sensor geometry, frequency, wavelength, time delays and amplitude depending on sensor configuration (wedge or array based), the structure being inspected and the region of the structure being inspected. Guided waves offer an infinite number of choices for such operating points and the decision-making process can require extensive modeling and development activity. Performance-critical structures in particular require optimal selection of the operating points as they have a limited margin of error.

SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

In one embodiment, a method of selecting operating parameters for inspecting a structure includes exciting broadband ultrasonic guided waves in a multilayered structure, acquiring, by an inspection tool capable of sensing the broadband ultrasonic guided waves in the multilayered structure, data corresponding to the sensed broadband ultrasonic guided waves in the multilayered structure, selecting one or more narrow frequency bands based on the acquired data, and inspecting the multilayered structure using ultrasonic guided waves in the one or more narrow frequency bands.

In one example, the multilayered structure includes a coated metallic pipe having one or more of a varying wall thickness, a varying coating thickness, or a varying quality. In another example, the inspection tool is an electromagnetic acoustic transducer based inline inspection tool. In another example, the one or more narrow frequency bands comprise a long pulse width with a plurality of cycles. In another example, the ultrasonic guided waves in the one or more narrow frequency bands have a higher intensity than the broadband ultrasonic guided waves.

In another embodiment, a system of selecting operating parameters for inspecting a structure includes an ultrasonic transmitter, an ultrasonic receiver, and a controller. The ultrasonic transmitter is configured to excite broadband ultrasonic guided waves in a multilayered structure. The ultrasonic receiver is configured to sense the broadband ultrasonic guided waves in the multilayered structure and to generate data corresponding to the sensed broadband ultrasonic guided waves in the multilayered structure. The controller is configured to select, based on the acquired data, a narrow frequency bandwidth of ultrasonic guided waves for use in a subsequent inspection of the multilayered structure.

In one example, the multilayered structure includes a coated structure. In another example, the ultrasonic transmitter is configured to excite the broadband ultrasonic guided waves in one of a plurality of layers of the multilayered structure, and the ultrasonic receiver is configured to sense the broadband ultrasonic guided waves in the at least one of the plurality of layers. In another example, the ultrasonic receiver is configured to traverse the structure while sensing the broadband ultrasonic guided waves in the coated structure. In another example, the ultrasonic receiver includes a guided wave phased transducer array installed on the coated structure. In another example, the guided wave phased transducer array includes one or more additional receivers configured to sense the broadband ultrasonic guided waves in a load carrying portion of the structure. In another example, the ultrasonic transmitter is an ultrasonic transceiver configured to receive ultrasonic signals. In another example, the ultrasonic transmitter is configured to traverse the structure while transmitting the broadband ultrasonic guided waves in the multilayered structure. In another example, the ultrasonic transmitter and the ultrasonic receiver have physical access only to the outermost layer of the multilayered structure and a broadband signal method is used to find an optimal and physically verifiable operating point.

In another embodiment, a computer readable storage medium has embodied thereon instructions for selecting operating parameters for inspecting a structure. The instructions, in response to execution by a computing device, cause the computing device to excite broadband ultrasonic guided waves in a multilayered structure, acquire, from an inspection tool capable of sensing the broadband ultrasonic guided waves in the multilayered structure, data corresponding to the sensed broadband ultrasonic guided waves in the multilayered structure, select one or more narrow frequency bands based on the acquired data, and inspect the multilayered structure using ultrasonic guided waves in the one or more narrow frequency bands.

In one example, the multilayered structure comprises a coated metallic pipe having one or more of a varying wall thickness, a varying coating thickness, or a varying quality. In another example, the inspection tool is an electromagnetic acoustic transducer based inline inspection tool. In another example, the one or more narrow frequency bands comprise a long pulse width with a plurality of cycles. In another example, the ultrasonic guided waves in the one or more narrow frequency bands have a higher intensity than the broadband ultrasonic guided waves.

