The main aim of the research was to investigate the influence of number and size of scattered knots and knot clusters on wooden board modulus of elasticity (MOE). More than 100 structural size Lithuanian-grown Scots pine wood pieces having various lengthwise knot configurations has been tested. In the first part of the research global MOE of the wood pieces was specified using “Timber Grader MTG” and related to the location and sizes of knots. Effects of total board surface knot area ratios as well as dominant knot cluster influence on board global stiffness was evaluated and compared to specify verifiable and simplified stiffness prediction method. Afterwards local MOE profiles in specific parts of the wood (especially with knots) lengthwise wood pieces were established using acoustic time-of-flight method and Strength Meter developed at KTU. Other physical wood properties like density, annual rings, and moisture content has been also incorporated into data processing and modelling.
The main focus of investigating was knots-related effects. Every knot in all the samples (diameter higher than 10mm) has been counted, and their surface areas ratios calculated. Also certain areas, having the biggest knots concentrations were specified and interrelated with MOE values.
Comparative analysis of the main features of all the samples allowed evaluating the knots effects (location of knots, size and areas of knots and clusters) and other properties on wood MOE with the graphical 3D models for visualization the results.
Keywords: timber, knots, strength, stiffness
Authors
Baltrušaitis A.
Department of Materials Engineering, Kaunas University of Technology, Kaunas
Kalėda V.
Department of Materials Engineering, Kaunas University of Technology, Kaunas
Keturakis G.
Department of Materials Engineering, Kaunas University of Technology, Kaunas
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