Condition assessment of timber utility poles using ultrasonic guided waves

Abstract

In this study, guided stress waves were used to evaluate the conditions of a timber utility pole experimentally and numerically using COMSOL Multiphysics. Macro Fiber Composites (MFCs), due to their flexibility and convenience to install on curved surfaces, were used to actuate and sense guided waves along the tested specimens. Based on the wave propagation characteristics in these types of structures, an MFC actuator ring, which was developed in the previous work, was applied to tune and enhance the propagating wave modes. The designed ring was used to excite longitudinal ultrasonic wave modes, mainly L(0,1), to determine the embedded length of the pole and damage localization, in both traction free and embedded conditions. Embedding the timber in the soil had minimum impact on the wave propagation characteristics, given that the waves were confined in the timber pole with minimal leakage to the surrounding. The embedded length was determined accurately for the sound and the damaged timber specimen, using both experimental and numerical data with an error of less than 3%. The deterioration in the timber structure, within the embedded region, was also evaluated with high accuracy of 93%. Based on the obtained results, guided waves have a high potential to be used as a non-destructive tool for the assessment and evaluation of timber utility poles. © 2020 Elsevier Ltd