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 modelled 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 modelling approach presented incorporates all relevant knot information in a Bayesian framework, thereby contributing a more refined way of managing the quality of manufactured lumber.
翻译:在评估用于工程应用的锯木的强度时,结节的大小和位置是一个重要的考虑因素。树枝生长后,结节的大小和位置是木材最常见的视觉特征。据了解,大型的个别结节和结节的组群具有减少强度的效果。不过,关于结节的行业分级规则在某种程度上是根据主观判断,特别是结节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的结果,该实验调查和模拟了结结结对道格拉斯·法尔木材样品的减强度影响。实验数据是通过扫描木材表面和采用抗拉强度测试获得的。提出的模型方法将贝叶斯框架所有相关的结点信息纳入其中,从而有助于以更完善的方式管理制成品木材的质量。