Structural Damage Identification in Homogeneous and Heterogeneous Structures Using Beamforming

Abstract

In this study, beamformers consisting of phased sensor or actuator arrays are used in the nondestructive evaluation of homogeneous and heterogeneous structural components. Beamforming can be used to detect, locate, and quantify damage by suitably applying weights and time or phase delays to the tapped signals from a sensor array and/or actuator array in a narrow frequency band to obtain the desired directional sensitivities and optimal array gains. Some aspects about beamforming and wave propagation are discussed as a prelude to the experimental investigation. Design considerations for the phased arrays are also examined. The advantages of using adaptive over conventional beamforming are demonstrated with Frost constraint- and pilot signal-based adaptive techniques. Data from steel and composite plates are analyzed using propagating elastic waves and phased arrays of sensors and/or actuators. Damage, which can be characterized as a local change in impedance, is diagnosed by using propagating elastic waves as they are sensitive to small changes in impedance and do not require a large number of input/output transducers. Beamforming of sensor and/or actuator arrays is carried out to characterize damage in steel and composite plates by comparing the directivity patterns associated with the damage and baseline data.

In situ 2-D piezoelectric wafer active sensors arrays for guided wave damage detection

“…This method was introduced into the ultrasonic testing due to multiple advantages such as flexible beam control, good manipulation and, most importantly, reduced inspection time [1,2]. Using an ultrasonic phased array, the ultrasonic wave front can be focused in a certain point or steered in a specific direction and thus the inspection of a wide area can be achieved by electronically sweeping and/or refocusing without physically manipulating the transducers.…”

Identification of Impact Damage in S-2 Glass Composite Missile Casings Using Complementary Vibration and Wave Propagation Approaches

“…The associated broadband dispersive character of this waveform along with associated corrections for the cylindrical nature of the specimen and the material anisotropy were incorporated into the analysis. The work described herein represents an extension to the model and experiments described previously in [18,19]. In this prior work, phased array beamformers consisting of sensor/actuator arrays were used to locate damage in steel and composite plates.…”

Wavlet-Based Active Sensing for Health Monitoring of Plate Structures using Baseline Free Ultrasonic Guided Wave Signals

“…A reference free technique based on instantaneous baseline measurements has been proposed recently by Anton et al [21]. The other method, such as, phased array beam forming [22][23][24] has been considered as alternatives, however, with some knowledge of the structure in a healthy state, such as group velocity information. These methods deploy 'linear array' of multitransmitter and multi-receiver (MTMR) and suitably apply weights and time or phase delays to the tapped signals from a sensor array and/or actuator array to obtain the desired directional sensitivities and optimal array gains.…”