Experimental validation of a novel structural damage detection method based on empirical mode decomposition

Structural health monitoring, as a non-destructive damage detection technique, has been adopted by many researchers as well as various industries to keep up with the increasing demand for preventive maintenance routines. Oil and gas is one of the major industries in which effective damage detection can ensure reliable transportation of chemicals and provide tremendous savings in maintenance costs. The present work investigates the integrity of a novel damage detection method through a set of experiments conducted on a standard steel pipe commonly used in the oil and gas industry. The method involved collection of the vibration signature of the pipe via certain sensors, and decomposition of the signature (signals) by empirical mode decomposition. This was followed by the use of a damage index defined on the first intrinsic mode function resulting from the decomposition. The experiment consisted of a cantilever steel pipe equipped with piezoceramic sensors to monitor the free vibration of a pipe impacted by an impulse hammer. Three damage cases were studied including single half-circumferential, single full-circumferential, and multiple circumferential and half-circumferential damages. A MATLAB code was developed to process and to decompose the signals according to the proposed methodology. The results showed that the proposed damage detection methodology could successfully detect the presence and location of damage, and could also identify the severity of the damage. A set of experiments was also done to examine the effect of support flexibility on the damage index, and to examine the sensitivity of the method to support conditions.