Kumar Manoj, Shakher Chandra
Appl Opt. 2016 Feb 10;55(5):960-8. doi: 10.1364/AO.55.000960.
In this paper, an application of digital holography for the measurement of surface deformations and the strain field to understand the shrinkage behavior of wood during convective drying is presented. Moisture absorption and desorption induce the dimensional changes and deformations in wood that leads to failure of certain components made of wood. The knowledge of the dimensional changes in wood, deformations, strain distribution and their causes are important for the best utilization of wood. For the study, lensless Fourier transform digital holographic interferometry is used to measure moisture- induced deformation, strain distribution, and the coefficient of hygroscopic shrinkage in different samples of wood. The technique is highly sensitive and enables the observation of deformation and strain distribution during the variations of moisture content in the wood. The wet wood sample was exposed to convective drying, which leads to changes in the moisture content and the associated deformations. The deformation/strain in each step of drying process is used to evaluate the coefficient of hygroscopic shrinkage in different wood samples. The experiments were repeated for differently treated woods. The experimental results show that the strain and coefficient of hygroscopic shrinkage can be minimized if the wood is dried in the presence of the proper moisture content.
本文介绍了数字全息术在测量表面变形和应变场以了解木材在对流干燥过程中的收缩行为方面的应用。木材中的吸湿和解吸会引起尺寸变化和变形，从而导致某些木制部件失效。了解木材的尺寸变化、变形、应变分布及其原因对于木材的最佳利用至关重要。在本研究中，无透镜傅里叶变换数字全息干涉术用于测量不同木材样品中水分引起的变形、应变分布和吸湿收缩系数。该技术高度灵敏，能够观察木材中水分含量变化期间的变形和应变分布。湿木材样品进行对流干燥，这会导致水分含量变化以及相关的变形。干燥过程中每个步骤的变形/应变用于评估不同木材样品的吸湿收缩系数。对不同处理的木材重复进行实验。实验结果表明，如果木材在适当的水分含量条件下干燥，应变和吸湿收缩系数可以最小化。
