Abstract

When assessing the strength of sawn lumber for use in engineering applications, the sizes and locations of knots are an important consideration. Knots are the most common visual characteristics of lumber, that result from the growth of tree branches. Large individual knots, as well as clusters of distinct knots, are known to have strength-reducing effects. However, industry grading rules that govern knots are informed by subjective judgment to some extent, particularly the spatial interaction of knots and their relationship with lumber strength. This case study reports the results of an experiment that investigated and modeled the strength-reducing effects of knots on a sample of Douglas Fir lumber. Experimental data were obtained by taking scans of lumber surfaces and applying tensile strength testing. The modeling approach presented incorporates all relevant knot information in a Bayesian framework, thereby contributing a more refined way of managing the quality of manufactured lumber.

摘要

在评估工程应用中使用的锯材的强度时，节的尺寸和位置是一个重要的考虑因素。节子是木材最常见的视觉特征，是由于树枝生长而产生的。众所周知，大的单个结以及不同结的簇会降低强度。然而，管理节子的行业分级规则在某种程度上是由主观判断决定的，特别是节子的空间相互作用及其与木材强度的关系。本案例研究报告了一项实验结果，该实验调查并模拟了花旗松木材样本上的节子强度降低效应。实验数据是通过扫描木材表面并应用拉伸强度测试获得的。