Document Type : Research Paper

Authors

1 MSc.in forestry, Natural Resources Faculty, University of Guilan, Iran

2 Associate Professor of Forestry Department, Faculty of Natural Resources, University of Guilan, Iran

3 Professor, Faculty of Natural Resources, University of Guilan, Iran

4 Professor, Faculty of Natural Resources, Azad university of Karaj, Karaj, Iran

Abstract

The knot is the branch impact on the tree's trunk which reduces the quality of the wood. Knots or occlusion branches are the most important factor in the grading of woods. The purpose of this research is to detect and distinguish the size of the knot in the beech tree stem by non-destructive stress wave method. In this research, five one-meter stems were examined and according to the knot size, the stems were classified into four parts without knots, with small, medium and large knots. By using the FAKOPP microsecond timer device, stress waves were passed along the length of the stem and the width of the knots in the four parts of the stem. The amount of the stress waves velocity were calculated according to the transit time of the stress waves and also percentage of the Relative Velocity decrease of Stress waves were calculated. Analysis variance of the data showed between the four parts there is a significant difference at the 95% confidence level. The results showed that the size of knot has effective on the Relative Velocity decrease of Stress waves in the beech tree stem. As the knot gets bigger, its angle decreases with the main stem axis. consequently more length is placed in the stem, and the speed of its occlusion increases. In this method,very small knots whose percentage of the Relative Velocity decrease of Stress waves was less than 10% were not detected. Therefore, for small, medium and large knots, the range of Relative Velocity decrease of Stress waves were obtained 10-20%, 20-45% and more than 45%, respectively.

Keywords

-Amini, M., Sagheb-Talebi, Kh,. Namiranian,M and Amini, R.2009. Investigation on increment of Fagus orientalis Lipsky using time series analysis, Iranian Journal of Forest and Poplar Research,17(3):404-421 (In Persian).
-Armstrong, J.P.; Patterson, D.W.; Sneckenberger, J.E. 1991.Comparison of three equations for predicting stress wave velocity as a function of grain angle. Wood and Fiber Science,23(1):32.43.
-Barriola,M.J., Aira,J.R and Villanueva,J.L. 2021. Analytical models of the mechanical properties of Japanese larch (Larix kaempferi (Lamb.) Carr.) based on non destructive testing and visual grading parameters. Wood Material Science & Engineering,16(2):94-101.
- Dackermann,U., Crews,K., Kasal,B., Li,J., Riggio,M., Rinn,F and Tannert,T.2013. In situ assessment of structural timber using stress-wave.Measurements. Materials and Structures.DOI 10.1617/s11527-013-0095-4
-Duong,D.V and Ridley-Ellis,D. 2021.Estimating mechanical properties of clear wood from ten‐year‐old Melia azedarach trees using the stress wave method. European Journal of Wood and Wood Products,79:941–949.
-Guntekin,E., Ozkan,S and Yilmaz,T.2014.Prediction of bending properties for beech lumber using stress wave method. Maderas. Ciencia y tecnología 16(1): 93-98, DOI 10.4067/S0718-221X2014005000008
-Jung, J. 1979. Stress wave grading techniques on veneer sheets. Gen. Tech. Rep. FPL.GTR.27. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory.
-Kartoolinejad,D.,Najafi,A and Kazemi-Najafi,S.2013.Decay evaluation of damaged beech trees (Fagus orientalis L.) adjacent to skid trails by nondestructive stress wave technique, Iranian Journal of Forest and Poplar Research, 20( 4):622-633 (In Persian).
-Lotfi,S., Saadatnia,M.A., Moradian,M.H and Poursartip,L.2021. Investigation on biomechanical properties of Pinus nigra Using stress wave technique and resistography, Iranian Journal of Wood and Paper Science Research, 36 (2):144-156(In Persian).
- Ohara,K.L.2007.Pruning Wounds and Occlusion: A Long-Standing Conundrum in Forestry, Journal of Forestry, 105(3):131-138.
-Oven.P., Merela.M., Mikac.U and Sersˇa.I.2008. 3D magnetic resonance microscopy of a wounded beech branch,  Holzforschung, 62:322–328. DOI 10.1515/HF.2008.022        
-Račko, V.2013.Verify the accuracy of estimation the model between dimensional characteristics of branch scar and the location of the knot in the beech trunk. Forestry and Wood Technology, 84:60–65.
-Roohnia, M., A, Tajdini & N, Manouchehri.2011. Assessing wood in sounding boards considering the ratio of acoustical. NDT&E International, 44(1):13-20.
-Sambuelli.L.,Socco.L.V.,Godio.A.,Nicolotti.G and Martinis.R.2003.Ultrasonic, electric and radar measurements for living trees assessment, Bollettino di Geofisica Teorica ed Applicata, 44(3): 253-279.
- Sioma, A.2015. Assessment of wood surface defects based on 3D image analysis. Wood Research, 60(3):339–350.
- Sioma, A. and Socha, J.2016. Automation of annual tree increment measurement using vision system, Drewno, 59(196):19–30.
-Stängle, S. M., Brüchert, F., Kretschmer, U., Spiecker, H. and Sauter, U. H.2014.Clear wood content in standing trees predicted from branch scar measurements with terrestrial LiDAR and verified with X-ray computed tomography. Canadian Journal of Forest Research, 44(2):145– 153.
-Thomas, L., Milli, L., Thomas, R. E. and Shaffer, C. A. (2006) Defect detection on hardwood logs using laser scanning. Wood & Fiber Science, 38(4): 682–695.
-Torkaman,T., Vaziri,M., Sandberg,D and Mohammadi Limaei,S.2018. Relationship between branch-scar parameters and knot features of oriental beech (Fagus orientalis Libsky), Wood Material Science & Engineering. Article in Wood Material Science and Engineering · DOI: 10.1080/17480272.2018.1424731
-Torkaman,T., Vaziri,M., Sandberg,D and Mohammadi Limaei,S.2019. Comparison study in the clear wood estimation of the Beech tree trunk (Fagus orientalis Libsky), Iranian Journal of Wood and Paper Industries, 10(1):11-19 (In Persian).
-Wang, C., Zhao, Z., Hein, S., Zeng, J., Schuler, J., Guo, J., Guo, W. and Zeng, J.2015. Effect of planting density on knot attributes and branch occlusion of  Betula alnoides under natural pruning in southern China. Forests,6:1343–1361.
- Zadfallh,M., Naghdi,R.,Torkaman,J., Roohnia,M., Hedayati- Ayandeh,M.2021. Evaluation of the internal decay of the oak tree ( Quercus castaneifolia ) via the non - destructive test of the acoustic tomography, Iranian Journal of Wood and Paper Industries, 12(1):163-173(In Persian).