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.
Highlights
During the life cycle of a metallic structure, the appearance of damage is inevitable due to the structure’s complex working environments [1,2,3]
This paper presents a non-destructive damage detection, visualization, and quantification techniqueThis based on laser-generated ultrasonics anddamage state-space predictive models
Different types of paper presents a non-destructive detection, visualization, and quantification technique based on laser-generated ultrasonics and state-space predictive models
Summary
During the life cycle of a metallic structure, the appearance of damage is inevitable due to the structure’s complex working environments [1,2,3]. Duffour et al [14] investigated the application of the nonlinear vibro-acoustic modulation technique for the assessment of fatigue cracks in steel beams and nickel-based alloy plates. In their experiments, the specimens were subjected to both a low ultrasound frequency and a low structural vibration frequency. In the research mentioned above, the nonlinear ultrasonic technique was demonstrated to be a good candidate for the detection of fatigue damage This technique has some shortcomings in that it is challenging to get the two most suitable independent original excitation frequencies in practice [19].
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have