Toward identifying crack-length-related resonances in acoustic emission waveforms for structural health monitoring applications

Abstract

In this study, we focus on analyzing the acoustic emission waveforms of the fatigue crack growth despite the conventional statistics-based analysis of acoustic emission. The acoustic emission monitoring technique is a well-known approach in the non-destructive evaluation/structural health monitoring research field. The growth of the fatigue crack causes the acoustic emission in the material that propagates in the structure. The acoustic emission happens not only from the crack growth but also from the interaction of the crack tips during the fatigue loading in the structure. The acoustic emission waveforms are generated from the acoustic emission events; they propagate and create local vibration modes along the crack faces (crack resonance). In-situ fatigue and acoustic emission experiments were conducted to monitor the acoustic emission waveforms from the fatigue cracks. Several test specimens were used in the fatigue experiments, and corresponding acoustic emission waveforms were captured. The acoustic emission waveforms were analyzed and distinguished into three types based on the similar nature in both time and frequency domains. Three-dimensional harmonic finite element analyses were performed to identify the local vibration modes. The local crack resonance phenomenon has been observed from the finite element simulation that could potentially give the geometric information of the crack. The laser Doppler vibrometry experiment was performed to identify the crack resonance phenomenon, and the experimental results were used to verify the simulated results.

Advantages of Condition-Based Maintenance over Scheduled Maintenance Using Structural Health Monitoring System

“…Passive sensors detect signals generated by damage due to the evolution of the damage, which does not require an external excitation. Acoustic emission belongs to this category [11]. If damage is detected during flight, this can be a useful method.…”

Experimental and Computational Analysis of Acoustic Emission Waveforms for SHM Applications

“…These sensors were also used to detect the AE waveforms for simple pencil lead breaks AE in the past [8]. Efforts were made to retrieve the structural feature related information from the AE waveforms [9] Sagar et al [10] reported a relationship between AE and fracture parameters to estimate the crack geometry.…”

“…The detail of the dipole loading FEM parameters can be found in ref. [9]. We may hypothesize two physical phenomena to explain underlying physics behind the two types of AE waveforms.…”

Acoustic Emission Signal Analysis and Event Extraction through Tuned Wavelet Packet Transform and Continuous Wavelet Transform While Tensile Testing the AA 2219 Coupon

“…The phenomena related to crack resonance was identified through peak frequency based analysis. 9 Wavelet transform based frequency approach was efficiently utilized by Yang et al for the classification of different failure mechanisms of thermal barrier coatings. 10 Investigation on the damage behaviour of the thermal barrier coatings attacked by molten calcium-magnesium-alumino-silicate was executed using AE system by L.Yang, et al The discrimination of failure modes is obtained using wavelet packet transform technique.…”