Lamb Wave Propagation in Varying Isothermal Environments

Abstract

Military and commercial aerospace organizations are exploring structural health monitoring (SHM) systems to reduce maintenance costs and to verify the integrity of structural components exposed to harsh conditions. This technical note considers the use of Lamb waves to monitor plate and shell components of aerospace structures. For fielded applications, SHM systems will need to operate across a variety of environmental conditions, including large temperature ranges. Therefore, it is critical to understand the effects of temperature on Lamb wave propagation. The focus of this study is the effect of temperature on Lamb wave propagation in a constant-thickness metallic plate under isothermal conditions. Experimental measurements and analytical predictions are made over temperatures ranging from -18°C to 107°C. Results indicate that only small and predictable changes in the wave propagation behavior occur over the temperature range investigated. This is significant because it may allow SHM systems to be designed for aircraft systems operating within this range without the need for complex compensation techniques.

A data-driven temperature compensation approach for Structural Health Monitoring using Lamb waves

“…The difference of signals is used to locate and size the damage in the structure. This simple but often effective technique for damage detection can become a challenging task when environment or operational conditions (EOC) change (Andrews et al, 2008;Lee et al, 2011). Temperature change is the dominant EOC property that affects the robustness of a GWSHM system.…”

Reference-free crack detection under varying temperature

“…The amplitude increase and phase delay of the signals were observed as the temperature increased from -30 o C to 70 o C. The Young's modulus of Aluminum decreased with increasing temperature (Department of Defense Handbook, 2003), and as a result, the group velocities of the propagating wave packets declined. Therefore, a delay of the arrival time was observed for the signals propagated at higher temperatures (Andrews et al, 2008). It should be noted that because the temperature variation itself caused significant changes in the measured signal's amplitude and phase as shown in Fig.…”

Multiscale Modeling of Advanced Materials for Damage Prediction and Structural Health Monitoring

“…Among the various techniques used for NDE and SHM of aerospace, civil, and mechanical structures, GW-based techniques have been proven most effective and efficient because of their wide array of applications and sensitivity to multiple types, locations, and severities of damage (Raghavan and Cesnik, 2007;Andrews et al, 2008;Giurgiutiu, 2008). One of the most promising GW-based approaches for damage detection in advanced aerospace structures is Lamb wave based techniques (Alleyne and Cawley, 1992;Staszewski et al, 1997;Giurgiutiu, 2008;Jha and Watkins, 2009).…”

“…Guided wave-based SHM techniques for the purpose of damage detection in carbon fiber reinforced composite plate-like geometries have been proven to be one of the most effective, economical, and accurate means of performing SHM on advanced aerospace structures (Raghavan and Cesnik, 2007;Giurgiutiu, 2008;Andrews et al, 2008). One specific type of GW, Lamb waves, has demonstrated its effectiveness in in-situ characterization of damage in aerospace composites due to its ability to travel great distances in plate-like structures and sensitivity to small-scale damage (Alleyne and Cawley, 1992;Staszewski et al, 1997;Giurgiutiu, 2008;Jha and Watkins, 2009).…”