School of Urban Construction, Yangtze University, Jingzhou 434023, China.
Department of Mechanical Engineering, University of Houston, Houston, TX 77204, USA.
Sensors (Basel). 2018 Sep 14;18(9):3100. doi: 10.3390/s18093100.
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.
近年来，压电器件激励的主动传感技术已广泛应用于土木工程中的结构损伤检测和健康监测。木材作为一种建筑材料，在许多国家都得到了广泛的应用，因为它是丰富且可再生的。然而，木材在建筑中的一个更具挑战性的应用是水分可能造成的潜在损坏。增加的水分可能会导致木材部件更容易翘曲，并鼓励集成金属部件的腐蚀，除了可能导致腐烂和腐朽之外。然而，尽管人们努力检查和监测木材的水分含量，但缺乏一种方法可以提供真正实时、定量和非侵入性的木材水分测量。因此，本文研究了使用一对粘贴在木材样本表面的锆钛酸铅（PZT）换能器通过主动传感方法进行水分含量监测的可行性。在主动传感方案中使用一对换能器，一个贴片产生设计的应力波，而另一个贴片接收信号。在主动传感激活期间，木材样本的水分含量从 0%逐渐增加到 60%，每次增加 10%。木材的材料特性在不同的木材水分含量下相应地发生变化，导致不同样本的应力波衰减率有可测量的差异。实验结果表明，接收信号的能量和木材样本的水分含量呈抛物线关系。最后，讨论了该方法监测木材水分含量的可行性和可靠性。
