Lamb Wave Propagation in Varying Isothermal Environments

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.