Related Links
Investigating the effect of knot size on the dynamic modulus of elasticity of beech wood (Fagus orientalis Libsky) | ||
| تحقیقات علوم چوب و کاغذ ایران | ||
| Article 5, Volume 39, Issue 3 - Serial Number 88, October 2024, Pages 198-212 PDF (1.44 M) | ||
| Document Type: Research Paper | ||
| DOI: 10.22092/ijwpr.2024.365915.1774 | ||
| Authors | ||
| Javad Torkaman* 1; Ramin Naghdi2 | ||
| 1Associate Professor of Forestry Department, Faculty of Natural Resources, University of Guilan, Iran | ||
| 2Professor, Faculty of Natural Resources , University of Guilan, Iran | ||
| Abstract | ||
| Background and purpose: Dynamic methods (non-destructive) work on the basis of creating tension without failure in the samples and save time and costs for evaluating mechanical properties. Knots or the encapsulated branches are the most important factor in the grading of wood. Therefore, the objectives of this research are: detection of knots by non-destructive methods, measuring the dynamic modulus of elasticity of beech log using stress waves, and the effect of knot size on the speed of stress waves Subsequently, the value of dynamic modulus of elasticity. Materials and methods: The studied area of Shafarood series 11, which is located in the southern part of the Shafarood watershed, starts at an altitude of 500 meters and continues up to an altitude of 1650 meters. From this area, Five number of beech trees were cut and divided into three equal parts of three meters by transverse cutting, and according to the size of the knots, the properties of density, stress waves velocity Subsequently, the dynamic modulus of elasticity were measured. From the tangential image of the external indicator and the radial image of the internal indicator by using the Digimizer image4 software, the characteristics of each knot such as the diameter and angle of the knot were measured. For non-destructive detection of beech tree knot, ultrasonic tomography, stress wave velocity and CT scan methods were used. In the stress waves velocity method, a Fakopp microsecond timer device was used to measure the time of stress waves velocity. In the radiographic method as well to prepare CT scan images, A digital ground column device with two detectors made in France belonging to a medical clinic was used. To measure the density, 30 cylindrical stems with knots of small, medium and large classes were used, and according to the relationship between density and stress wave velocity, the value of dynamic elasticity modulus was calculated and evaluated. The diameter of the knot along the length of the stem, the density and the dynamic modulus of elasticity of the beech tree stem were measured. To analyze the data at the 95% confidence level, the one-way Anova test was used, and to determine the normality of the data and the homogeneity of the variance, the Kalmograph Smirnov and Leven tests were used. To compare the means, Tukey's test was used by using Spss software. Results: In the detection of beech tree knot with the three mentioned non-destructive methods, the results show the existence of limitations in each method. As the ultrasonic tomography is not able to detect knots inside the beech tree trunk and the stress wave method also does not detect very small knots. The accuracy of the CT scan method in detecting the knot is high, but the cost of its detection is high. According to the growth stages of the beech tree, factors such as growth speed, branch encapsulation speed and natural pruning are different. The origin of the branch is pith of the stem. As a result, the number and size of the created knots are different along the tree. Therefore, most of the small knots are created in the main trunk of the tree. The diameter of the knot has also increased with the increase in the height of the stem. The knot has increased the density. The density results have shown that the samples with large, medium and small knots have significant differences. Considering that the ultrasonic tomography method is based on the reduction of density, it is not able to detect the knot. But in the radiography method, the parts with higher density are seen in light color and the parts with lower density are seen in darker color. The size of the knot is effective on reducing the speed of stress waves and thus reducing the dynamic modulus of elasticity of wood. In comparison with the samples without knots, the samples with small, medium and large knots reduce the modulus of elasticity by 20%, 50% and 70% respectively. Conclusion: in general, among the non-destructive methods, only the CT scan method is able to detect small knots and evaluate the clear wood and defects. In comparison with the control sample (without knots), with increasing the size of the knot, the value of the density increases and the stress wave velocity decreases Subsequently, the dynamic elasticity modulus of the samples decreases. | ||
| Keywords | ||
| Dynamic modulus of elasticity; Ultrasonic tomography; Stress wave velocity; CT scan | ||
| References | ||
|
-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).
-Bonyad, A.E., Torkaman, J. and Rohi, A., 2013. Growth stages and site components influence on form factors of beech (Fagus orientalis Lipsky).Iranian Journal of Forest, 5(2), 102–117. (In Persian).
-Divos, F. and Tanaka, T., 2005. Relation Between Static and Dynamic Modulus of Elasticity of Wood, Acta Silv. Lign. Hung., Vol. 1 (2005) 105-110.
-Ehrhart, T., Steiger, R. and Frangi, A., 2017.Impact and detection of grain direction in European beech wood, in Proceedings of INTER - Meeting Fifty, 2017, pp. 479–482.
-Grundberg S., 1994. Scanning for internal defects in logs. Licentiate Thesis 1994:14L, Division of Wood Technology, Luleå University of Technology, Skellefteå, Sweden. ISSN 0280-8242.
- Hein, S. and Spiecker, H., 2007. Comparative analysis of occluded branch characteristics for Fraxinus excelsior and Acer pseudoplatanus with natural and artificial pruning, Can. J. For. Res. 37: 1414–1426 (2007), doi:10.1139/X06-308
-Hongyue, Q., Ming, C., Yuan, H. and Jianhua, L., 2020. Effect of Trees Knot Defects on Wood Quality: A Review, IOP Conf. Series: Materials Science and Engineering 738 (2020) 012027 IOP Publishing doi:10.1088/1757-899X/738/1/012027
-Maguire D.A. and Hann D.W., 1987. A stem dissection technique for dating branch mortality and reconstructing past crown recession.Forest Science, 33:858–871.
-Madhoushi, M., Hashemi, S.M. and Behzad, M., 2008. Evaluation of influence of decay on dynamic and static moduli of elasticity in Iranain beech by using of NDT stress wave. J. Agric. Sci. Natur. Resour., Vol. 15(3), (In Persian).
-Madhoushi, M. and Boskabadi, Z., 2019. Relationship Between The Dynamic And Static Modulus Of Elasticity In Standing Trees And Sawn Lumbers Of Paulownia Fortune Planted In Iran. Maderas. Ciencia y tecnología 21(1): 35 - 44, DOI: 10.4067/S0718-221X2019005000104
-Mirabdollahi, M., Bonyad, A.E., Torkaman, J. and Bakhshandeh, B., 2011. Study on tree form of Oriental Beech (Fagus orientalis Lipsky) in different growth stages (Case study: Lomir forest), Iranian Journal of Forest, Vol.3, No.3:177-187. (In Persian).
-Oja J., 1997. A comparison between three different methods of measuring knot parameters in Picea abies. Scandinavial Journal of Forestry Research, 12, 311–315.
-Osterloh, K., 2006. Radiographic and Tomographic Testing of Wood, ECNDT 2006 - Th.1.3.3
-Pinto, I., Pereir, H. and Usenius, A., 2003. Analysis of log shape and internal knots in twenty maritime pine (Pinus pinaster Ait.) stems based on visual scanning and computer aided reconstruction. Annals of Forest Science, 60(2), 137–144.
-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.
-Rast, E.D., Beaton, J.A. and Sonderman, D.L., 1989. Photographic guide of selected external defect indicators and associated internal defects in white oak. USDA Forest Service North-eastern Forest Experiment Station, Broomall, USA, Report RPNE-628, p. 24.
-Rast, E.D., Beaton, J.A. and Sonderman, D.L., 1991a. Photographic guide of selected external defect indicators and associated internal defects in sugar maple. USDA Forest Service North-eastern Forest Experiment Station, Radnor, USA, Report RPNE-647, p. 29.
-Rast, E.D., Beaton, J.A. and Sonderman, D.L., 1991b. Photographic guide of selected external defect indicators and associated internal defects in yellow poplar. USDA Forest Service North-eastern Forest Experiment Station, Radnor, USA, Report RP-NE-646, p. 35.
-Samson, M., 1993. Method for assessing the effect of knots in the conversion of logs into structural lumber. Wood Fiber Science, 25, 298–304.
-Salehi, N., Torkaman, J., Naghdi, R. and Roohnia, M., 2022. Detection and differentiation of the beech wood knot (Fagus orientalis Libsky)by non-destructive stress wave method, Iranian Journal of Wood and Paper Science Research Vol. 37 No. (4):282-292.DOI: 10.22092/ijwpr.2022.358587.1718(In Persian).
-Schultz, H., 1961. Die Beurteilung der Qualitätsentwicklung junger Bäume.[Assessment of the quality development of young trees.] Forstarchiv, XXXII (May 15), pp. 89–99.
-Shigo, A.L. and Larson, E., 1969. A photo guide to the patterns of discoloration and decay in living northern hardwood trees. USFS, Northeast Forest and Range Experiment Station, Research Paper NE-127, 100 p.
-Sioma, A., 2015. Assessment of wood surface defects based on 3D image analysis. Wood Research, 60(3):339–350.
-Torkaman, j., Vaziri, M., Sandberg, Dand 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.
| ||
|
Statistics Article View: 163 PDF Download: 155 |
||
Journal management system. designed by sinaweb