The use of time reversal methods with Lamb waves to identify structural damage in a pipeline system

Abstract

Harsh environmental and operating conditions often leave pipeline systems prone to cracks, corrosion, and other aging defects. If left undetected, these forms of damage can lead to the failure of the pipeline system, which may have catastrophic consequences. Most current forms of health monitoring for pipeline systems involve nondestructive evaluation (NDE) techniques. These techniques often require a pipeline system to be taken out of operation at regularly scheduled intervals so that a technician can perform a prescribed NDE measurement. Such a measurement also requires direct access to the pipe's exterior or interior surface. This access may require excavation if the pipe is underground and the removal of insulating layers when present. This research proposes the use of Macro-fiber composite (MFC) actuators for damage detection in pipeline structures. Because MFC actuators are durable and relatively inexpensive, they can be permanently bonded to the surface of a pipe during installation. Therefore, measurements for damage detection can be performed at any time, even while the system is still in operation. The time reversal methods use the propagation of Lamb waves to evaluate the structural health of a pipeline system. A burst waveform is used to excite Lamb waves in a pipe at an initial location using an array of MFC patches. The measured response at the actuation location is reversed in time and used as the excitation signal at the second location. The initial excitation signal is then compared to the final response signal. The performance of the time reversal methods was compared to the traditional methods of Lamb wave propagations using standard tone burst waveforms.