A method for inspecting a bonded structure, the bonded structure having a first structural member, a second structural member, and a bondline between the first structural member and the second structural member, includes projecting acoustic waves into the bonded structure at a non-zero angle relative to a normal axis defined by an external surface of the first structural member. The method further includes determining a magnitude of a total refraction of the acoustic waves after the acoustic waves pass through the bonded structure and comparing the magnitude of the total refraction to a predefined value.

A system for detecting cracks in an underwater structure can include an acoustic signal transmitter configured to be disposed proximate to, but without physically contacting, the underwater structure, where the acoustic signal transmitter is configured to emit acoustic signals. The system can also include an acoustic field receiver configured to be disposed proximate to, but without physically contacting, the underwater structure, where the acoustic field receiver is configured to receive resulting acoustic fields. The system can further include a controller that is configured to receive the resulting acoustic fields from the acoustic field receiver. The controller can also be configured to analyze the resulting acoustic fields signal. The controller can further be configured to detect, based on analyzing the resulting acoustic fields, a crack in the underwater structure.

A method of inspecting a pipe joint of a pipeline in active operation includes installing, during or after initial assembly of the pipe joint, a layer of a material comprising graphene, a magnetostrictive material, or a combination thereof in the pipe joint, initiating operation of the pipeline to enable transportation of fluid therethrough, assessing, via one or more sensors provided at or near the layer of the material, symptoms of deterioration and/or anomalies within the pipe joint leading to deterioration of the pipe joint during operation of the pipeline, and designating the pipe joint for repair operations based upon the assessed symptoms of deterioration and/or anomalies within the pipe joint.