Correlation Analysis of Ultrasonic Stress Wave Characteristics and the Destructive Strength Measurements in Cylindrical Wooden Structure.

The utility sector has been employing ultrasonic-based nondestructive evaluation (NDE) to determine the cross-sectional groundline integrity of wooden utility poles. While it is far less invasive than other methods, its efficacy has not been thoroughly studied. This study aims to fill this technical gap by analyzing the correlation between the propagational characteristics of the ultrasonic stress wave using a novel embedded waveguide technique and the existing destructive testing methods. The proposed embedded waveguide technique excites diffusive Rayleigh mode (AW2) propagating in the shell region of the cross-sectional plane. This discovery allows a direct examination of the shell region condition through stress wave analysis. By employing the Gabor wavelet transformation and the model-based arrival region identification, this proposed technique extracts the propagation velocity and the associated spectral response of AW2. This study uses the static break assessment per ASTM 1036 Standard Test Methods And The longitudinal compression test per ASTM D143-14 "secondary method" to quantify the cross-sectional strength of the test specimen. This work performs a comprehensive correlation analysis between the extracted AW2 features and the associated destructive test. An overall correlation R from 0.2 to 0.5 is achieved between the AW2 features and the static break test results. An overall correlation of R of 0.4 is achieved for 30-35 ft poles in the longitudinal compression test.