Validation of Non-Destructive Wave Propagation Methods for MOE Assessment in Pinus, Eucalyptus and Cedar

Thermal modification (TM) enhances wood properties, but a gap exists in validating non-destructive testing (NDT) methods for thermally modified woods, as chemical and structural alterations may influence wave propagation. This study validated NDT wave propagation methods to estimate static MOE in Eucalyptus sp., Pinus sp., and Cedrela sp. woods subjected to TM (140 °C to 240 °C). Impulse excitation (longitudinal and flexural modes) and ultrasonic waves (90 kHz and 500 kHz) were used to obtain dynamic MOE, which was compared with static MOE obtained from three-point bending tests. Results showed high coefficients of determination (R2 > 90%) across all species and treatments. Longitudinal excitation presented the highest accuracy (R2 up to 97.96%); for ultrasound, 500 kHz was superior to 90 kHz. Control conditions and 240 °C resulted in the highest R2 values, indicating greater predictability. As a novel contribution, robust quantitative correlations between NDT methods and static MOE were established specifically for thermally modified tropical woods. Validated methods provide reliable tools for industrial quality control and process optimization, enabling rapid non-destructive assessment without material sacrifice.