Understanding the guided waves propagation behavior in timber utility poles
- PDF / 5,377,473 Bytes
- 21 Pages / 595.276 x 790.866 pts Page_size
- 10 Downloads / 155 Views
ORIGINAL PAPER
Understanding the guided waves propagation behavior in timber utility poles Jad El Najjar1 · Samir Mustapha1 Received: 3 February 2020 / Revised: 2 June 2020 / Accepted: 12 June 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Guided stress waves are considered one of the most efficient and reliable techniques that provide sufficient quantitative and qualitative assessment. In this study, we focused on scrutinizing the propagation behavior of guided waves in western white pine timber poles, experimentally, and numerically using COMSOL Multiphysics. Macro fiber composites (MFCs), due to their flexibility and convenience to install on curved profiles, were used to actuate and sense guided waves along the tested specimens. Various solutions for wave mode tuning and characterization have been tested for traction free and embedded boundary conditions. The behavior of propagating wave modes was analyzed and compared in the two boundary conditions tested. Also, the excitation frequency, based on the dispersion curves generated for transversely isotropic timber, was selected to ensure the presence of favorable propagating (for instance longitudinal modes) modes with minimal dispersion. Undesirable wave modes—such as flexural modes (non-axisymmetric)—were eliminated by a ring design composed of multiple MFC actuators coupled around the pole’s circumference. The remaining propagating longitudinal modes and their reflections, such as modes L(0,1) and L(0,2) propagating at nearly 1000 m/s and 800 m/s respectively, were significantly enhanced by the actuation of the ring which could be effectively used for the assessment process. The results demonstrated the complexity of the propagating modes in circular timber structures and the importance of the ring design in the excitation of the selected modes of interest and damping unwanted ones. Keywords Guided waves · Timber structures · Structural assessment · Finite element analysis · Macro fiber composites
1 Introduction The use of timber has commenced thousands of years ago and is still being used today in numerous applications. Being easy to manufacture and customize, practices vary from construction work, transportation applications, to equipment and infrastructure. When treated properly, timber can act as a substitute for many renowned materials such as steel and concrete. The cost of manufacturing, transportation, and storage is low compared to other materials, in addition to the ability to withstand handling and surface damage due to the lightweight and tough properties [1]. Also, timber has high tensile strength, high stiffness, and a relatively low density due to its composite structure containing interfaces [2]. The
* Samir Mustapha [email protected] 1
Mechanical Engineering, American University of Beirut, Beirut, Lebanon
machinability is extremely flexible and can accommodate to various requirements which widens their applications. One of the most famous and current applications of timber is in utility poles. These poles
Data Loading...
