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首页> 外文会议>International Symposium on Nondestructive Testing of Wood; 20000913-20000915; Sopron; HU >Nondestructive Evaluation of Standing Trees With Stress Wave Methods
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Nondestructive Evaluation of Standing Trees With Stress Wave Methods

机译：应力波法对立木无损评估

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Nature's engineering of wood through genetics, stand conditions, and environment creates wide variability in wood as a material, which in turn introduces difficulties in wood processing and utilization. Manufacturers sometimes find it difficult to consistently process wood into quality products because of its wide range of properties. The primary objective of this study was to investigate the usefulness of a stress wave technique for evaluating wood strength and stiffness of young-growth western hemlock and Sitka spruce in standing trees. A secondary objective was to determine if the effects of silvicultural practices on wood quality can be identified using this technique. Stress wave measurements were conducted on 168 young-growth western hemlock and Sitka spruce trees. After in situ measurements, a 2-ft- (0.61-m-) long bole section in the test span was taken from 56 felled trees to obtain small, clear wood specimens. Stress wave and static bending tests were then performed on these specimens to determine strength and stiffness. Results of this study indicate that in situ stress wave measurements could provide relatively accurate and reliable information that would enable nondestructive evaluation of wood properties in standing trees. The mean values of stress wave speed and dynamic modulus of elasticity for trees were in good agreement with those determined from small, clear wood specimens. Statistical regression analyses revealed strong relationships between stress wave properties of trees and static bending properties of small, clear wood specimens obtained from the trees. Regression models showed statistical significance at the 0.01 confidence level. Results of this study also demonstrate that the effect of silvicultural practices on wood properties can be identified with the stress wave properties of trees. This indicates that this nondestructive stress wave technique can be used to track property changes in trees and help determine how forests could be managed to meet desired wood and fiber qualities.
机译：自然界通过遗传，林分条件和环境对木材进行的工程设计使木材作为一种材料具有很大的变异性，这反过来给木材加工和利用带来了困难。制造商有时会发现，由于其广泛的性能，很难始终如一地将木材加工成优质产品。这项研究的主要目的是研究应力波技术在评估立木中年轻的西部铁杉和锡特卡云杉的木材强度和刚度方面的实用性。第二个目标是确定是否可以使用该技术确定造林实践对木材质量的影响。在168棵年轻的西部铁杉和Sitka云杉树上进行了应力波测量。在现场测量后，从56棵砍伐的树木中取出测试跨度为2英尺（0.61米）长的树干，以获取小的透明木材标本。然后对这些样品进行应力波和静态弯曲测试，以确定强度和刚度。这项研究的结果表明，现场应力波测量可以提供相对准确和可靠的信息，从而可以对立木的木材特性进行无损评估。树木的应力波速度和动态弹性模量的平均值与从小的透明木材样品中测得的平均值一致。统计回归分析表明，树木的应力波特性与从树木获得的小而透明的木材标本的静态弯曲特性之间存在很强的关系。回归模型在0.01置信水平上显示出统计显着性。这项研究的结果还表明，可以通过树木的应力波特性来确定造林实践对木材特性的影响。这表明这种无损应力波技术可用于跟踪树木的特性变化，并有助于确定如何管理森林以满足所需的木材和纤维质量。

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