A Feasibility Study on Timber Moisture Monitoring Using Piezoceramic Transducer-Enabled Active Sensing

Abstract

In recent years, the piezoceramic transducer-enabled active sensing technique has been extensively applied to structural damage detection and health monitoring, in civil engineering. Being abundant and renewable, timber has been widely used as a building material in many countries. However, one of the more challenging applications of timber, in construction, is the potential damage caused by moisture. Increased moisture may cause easier warping of timber components and encourage corrosion of integrated metal members, on top of potentially causing rot and decay. However, despite numerous efforts to inspect and monitor the moisture content of timber, there lacks a method that can provide truly real time, quantitative, and non-invasive measurement of timber moisture. Thus, the research presented in this paper investigated the feasibility of moisture-content monitoring using an active sensing approach, as enabled by a pair of the Lead Zirconate Titanate (PZT) transducers bonded on the surface of a timber specimen. Using a pair of transducers in an active sensing scheme, one patch generated a designed stress wave, while another patch received the signal. While the active sensing was active, the moisture content of the timber specimen was gradually increased from 0% to 60% with 10% increments. The material properties of the timber correspondingly changed under varying timber moisture content, resulting in a measurable differential in stress wave attenuation rates among the different specimens used. The experimental results indicated that the received signal energy and the moisture content of the timber specimens show a parabolic relationship. Finally, the feasibility and reliability of the presented method, for monitoring timber moisture content, are discussed.

Monitoring of Epoxy-Grouted Bonding Strength Development between an Anchored Steel Bar and Concrete Using PZT-Enabled Active Sensing

“…Furthermore, because of its strong piezoelectric effect [40,41] and wide bandwidth [42,43,44], Lead Zirconate Titanate (PZT) is one of the most commonly used piezoceramic materials, and is frequently utilized for stress wave generation [45,46,47,48] and detection [49,50,51]. Stress waves are often used in structural health monitoring [52,53,54,55,56], especially in the active sensing method [57,58,59,60,61] and the electromechanical impedance method [62,63,64,65,66]. The active sensing method was used for monitoring bolt loosening [58], very early age cement hydration [59], a bolted spherical joint connection [60], and timber moisture [61].…”

“…Stress waves are often used in structural health monitoring [52,53,54,55,56], especially in the active sensing method [57,58,59,60,61] and the electromechanical impedance method [62,63,64,65,66]. The active sensing method was used for monitoring bolt loosening [58], very early age cement hydration [59], a bolted spherical joint connection [60], and timber moisture [61]. The impedance method was used for monitoring the damage in plate-like structures [62], bolted joint looseness [63], pin connection loosening [64], the freeze–thaw process in soil [65], and a concrete-filled fiber-reinforced polymer tube [66].…”

Damage Analyses of Replaceable Links in Eccentrically Braced Frame (EBF) Subject to Cyclic Loading

“…Two PZT patches will be strategically placed across the potential location. The so-called active sensing method [71][72][73][74] will be adopted to monitor the cracks. In the active sensing approach, one PZT patch will be used to generate a stress wave that can propagate along a structure, and another PZT patch can also be used as a sensor to detect the stress wave.…”

Monitoring of Interfacial Debonding of Concrete Filled Pultrusion-GFRP Tubular Column Based on Piezoelectric Smart Aggregate and Wavelet Analysis

“…The piezoelectric transducer-based active sensing method combined with wavelet packet analysis was used by Yang W (2018) [52] to monitor the soil compactness, the results showed that the method can effectively identify the soil compaction degree. [53,54] detected the damage and moisture of timber by using PZT transducer-based active sensing, the results showed that the active monitoring method based on piezoelectric transducer can better identify the damage level and the moisture change of wood.…”