Detection and Quantification of Damage in Metallic Structures by Laser-Generated Ultrasonics

Abstract

Abstract:The appearance of damage on metallic structures is inevitable due to complex working environments. Non-destructive testing (NDT) of these structures is critical to the safe operation of the equipment. This paper presents a non-destructive damage detection, visualization, and quantification technique based on laser-generated ultrasonics. The undamaged and damaged metallic structures are irradiated with laser pulses to produce broadband input ultrasonic waves. Damage to the structures plays the role of a nonlinear radiation source of new frequencies. Usually these new frequencies are too weak to be detected directly. Here, the state space predictive model is proposed to address the problem. Based on the recorded responses in the time domain, the state space attractors are reconstructed. Damage to the structures is shown to change the properties of the attractors. A nonlinear damage detection feature called normalized nonlinear prediction error (NNPE) is extracted from the state space to identify the changes in the attractors-and hence the damage. Furthermore, the damage is visualized and quantified using the NNPE values extracted from the entire area by using a laser scanning technique. Experimental results validate that the proposed technique is capable of detecting, visualizing and quantifying artificial damage to aluminum alloy plates and actual fatigue cracks to a twin-screw compressor body.

Detection of Internal Holes in Additive Manufactured Ti-6Al-4V Part Using Laser Ultrasonic Testing

“…Furusawa et al utilized laser-induced ultrasonic guided wave technology to detect corrosion of the reinforced concrete structures [27]. Liu et al presented a non-destructive damage detection, visualization, and quantification technique based on laser-generated ultrasonics and state-space predictive models [28]. To date, few works have reported the application of the LUT method in the field of AM.…”

Dynamic Characteristics and Damage Detection of a Metallic Thermal Protection System Panel Using a Three-Dimensional Point Tracking Method and a Modal Assurance Criterion

“…Several experimental methods have been used for damage detection of structures: accelerometers [ 16 , 33 ], laser displacement measurement [ 34 , 35 ], photogrammetry [ 36 , 37 , 38 , 39 ], infrared thermography [ 40 ], and ultrasound [ 41 ]. Among them, the method that uses accelerometers has the effect of mass loading for lightweight structures and a labor-intensive and time-consuming process for large structures.…”

Analysis of Elastic Nonlinearity Using Continuous Waves: Validation and Applications

“…Materials with a very different microstructure, including consolidated [1][2][3][4][5] and unconsolidated [6] granular media or damaged composites and metallic materials [7][8][9][10][11], share a very similar elastic behaviour, in which hysteresis plays a crucial role. Their nonlinear response to an ultrasonic excitation is governed by a combination of effects due to velocity dependence on strain and attenuation nonlinearity [12][13][14][15].…”