Structural Health Monitoring of Adhesively Bonded Components in Aerospace Structures: Temperature Effect on Guided Wave Based Macro-Fiber Composite Transduction and Damage Detection

摘要

Monitoring of adhesively bonded CFRP composite joints through the use of ultrasonic guided waves is the focus of this paper. The examined components are representative of the wing skin-to-spar joints of unmanned aerial vehicles (UAVs). The study investigates two different types of bond defects, namely poorly cured adhesive and disbonded interfaces. The guided wave propagation problem is analytically studied by a proposed model that accounts for all relevant temperature-dependent parameters of a pitch-catch system on a CFRP composite plate. Actuator-plate and plate-sensor interactions through shear-lag behavior, piezoelectric and dielectric permittivity properties of the transducers and Lamb wave dispersion properties of the substrate plate are included in the model. The model is used to predict the S_0 response spectra in a composite plate for the temperature range of -40°Cto +60°C, which represents normal aircraft operational variability. Multiple guided wave features are considered in both the time and frequency domains. The statistical variation of these features due to large fluctuations in ambient temperature is quantified and used to populate the baseline data set. Automated damage identification within the joints is successfully achieved under changing environmental conditions using a multivariate outlier analysis.