TY - JOUR
T1 - Effects of high-amplitude low-frequency structural vibrations and machinery sound waves on ultrasonic guided wave propagation for health monitoring of composite aircraft primary structures
AU - Ochôa, Pedro A.
AU - Groves, Roger M.
AU - Benedictus, Rinze
PY - 2020/6/9
Y1 - 2020/6/9
N2 - A reliable damage diagnostic by ultrasonic guided wave (GW) based structural health monitoring (SHM) can only be achieved if the physical interactions between wave propagation, the SHM system and environmental factors are fully understood. The purpose of this research was to gain knowledge about the effects of high-amplitude low-frequency structural vibrations (HA-LFV) and audible sound waves (SW) on ultrasonic GW propagation. Measurements were performed on a stiffened panel of a full-scale composite torsion box containing barely visible impact damage. Time-domain analysis of the filtered GW signals revealed that the main effect of HA-LFV was the presence of coherent noise. This was interpreted as the consequence of superposition of multiple dispersive wave groups produced by mode conversion at the moment of reflection on the corrugated panel surfaces during propagation. It was also observed that the coherent noise amplitude depends on the amplitude of the HA-LFV, and on the ratio between the HA-LFV frequency and the ultrasonic excitation frequency. These relationships can potentially be explored for the development of a HA-LFV compensation mechanism to enable in-service GW based damage diagnostics. In contrast, GW signals in the cases with audible SW present were almost unaffected. It was concluded that there is strong evidence supporting the hypothesis that ultrasonic GW propagation with HA-LFV effects can be analysed under the assumption of a permanently corrugated structure.
AB - A reliable damage diagnostic by ultrasonic guided wave (GW) based structural health monitoring (SHM) can only be achieved if the physical interactions between wave propagation, the SHM system and environmental factors are fully understood. The purpose of this research was to gain knowledge about the effects of high-amplitude low-frequency structural vibrations (HA-LFV) and audible sound waves (SW) on ultrasonic GW propagation. Measurements were performed on a stiffened panel of a full-scale composite torsion box containing barely visible impact damage. Time-domain analysis of the filtered GW signals revealed that the main effect of HA-LFV was the presence of coherent noise. This was interpreted as the consequence of superposition of multiple dispersive wave groups produced by mode conversion at the moment of reflection on the corrugated panel surfaces during propagation. It was also observed that the coherent noise amplitude depends on the amplitude of the HA-LFV, and on the ratio between the HA-LFV frequency and the ultrasonic excitation frequency. These relationships can potentially be explored for the development of a HA-LFV compensation mechanism to enable in-service GW based damage diagnostics. In contrast, GW signals in the cases with audible SW present were almost unaffected. It was concluded that there is strong evidence supporting the hypothesis that ultrasonic GW propagation with HA-LFV effects can be analysed under the assumption of a permanently corrugated structure.
KW - Aircraft primary structure
KW - Composite materials
KW - Low-frequency vibration
KW - Structural health monitoring
KW - Ultrasonic guided wave
UR - http://www.scopus.com/inward/record.url?scp=85081127583&partnerID=8YFLogxK
U2 - 10.1016/j.jsv.2020.115289
DO - 10.1016/j.jsv.2020.115289
M3 - Article
AN - SCOPUS:85081127583
SN - 0022-460X
VL - 475
JO - Journal of Sound and Vibration
JF - Journal of Sound and Vibration
M1 - 115289
ER -