Sıcaklık ve Maruz Kalma Süresinin Meşe Odunu Eğilme Özelliklerine Etkisi

Abstract

Sıcaklık, malzeme özelliklerine ve malzemenin kullanım esnasındaki davranışına etkisi olan çevresel etkenlerden biridir. Bu çalışmada, sıcaklığın ve maruz kalma süresinin ultrasonik dalga hızı, dinamik elastikiyet modülü, eğilmede elastikiyet modülü ve eğilme direncine etkisi boyuna ultrasonik dalga yayımı ve üç nokta eğilme testi ile ortaya konulmuştur. Sonuçlara göre, tüm özellikler yoğun muamele koşullarında düşmüştür. En yüksek düşüş, % 4.7, 16.6, 20.7, 34.1 ve 8.7 ile 210 °C 8 saat muamele sonucu VLL, Edyn, MOE, MOR ve yoğunluk değerlerinde olmuştur. Fakat yoğunluk harici özellikler, 150 °C’ye kadar olan ılımlı sıcaklıklarda maruz kalma süresinin artışı ile birlikte grup içinde artarken (80 °C ve 8 saat için VLL: %12.7, Edyn: %20.2, MOE: %18.1, MOR: %11.7) gruplar arasında düşmüştür. Değişkenler arasındaki Pearson korelasyon katsayıları Edyn-MOE için 0.71’den 0.93’e, Edyn-MOR için 0.47’den 0.85’e, Edyn-VLL için 0.02’den 0.75’e, MOE-MOR için 0.71’den 0.88’e, MOE-VLL için 0.02’den 0.78’e ve MOR-VLL için 0.01’den 0.81’e kadar yayılmıştır. Ayrıca, R2 değerleri 0.7’den 0.9’a kadar

Keywords

• Meşe
• ultrases
• eğilme özellikleri,
• elastikiyet modülü

Influence of Temperature and Exposure Duration on the Bending Properties of Oak Wood

Abstract

Temperature is one of the environmental factors that has influences on the material properties, and its behavior in service life. In this study, effects of temperature and exposure duration on the ultrasound wave velocity, dynamic Modulus of Elasticity, Modulus of Elasticity in bending, and Modulus of Rupture were figured out by the transmission of ultrasound longitudinal wave and three points bending tests. According to results, all determined properties were decreased at intensive treatment conditions. Maximum decreases were 4.7, 16.6, 20.7, 34.1, and 8.7 % at 210 °C 8 h treatments for VLL, Edyn, MOE, MOR, and density, respectively. However, at moderate temperatures up-to 150 °C, properties (except density) were increased (VLL: 12.7%, Edyn: 20.2%, MOE: 18.1%, MOR: 11.7% at 80°C for 8h) with the increase in exposure time within the groups but decreased between the groups. Pearson correlation coefficients between the variables were ranged from 0.71 to 0.93 for Edyn-MOE, 0.47 to 0.85 for Edyn-MOR, 0.02 to 0.75 for Edyn-VLL, 0.71 to 0.88 for MOE-MOR, 0.02 to 0.78 for MOE-VLL, and 0.01 to 0.81 for MOR-VLL. Furthermore, R2 values were ranged from 0.7 to 0.9.

Keywords

• oak
• ultrasound
• bending properties
• modulus of elasticity

References

1. 1. Aydin, T.Y. (2020). Ultrasonic evaluation of time and temperature-dependent orthotropic compression properties of oak wood. J Mater Res Technol, 9(3):6028-6036.
2. 2. Bahar, R., Ouertani, S., Azzouz, S., Naili, H., El Ayeb, M.T., El Cafci, A. (2019). Mechanical properties changes in oak (Quersus canariensis) and stone pine (Pinus pinea) wood subjected to various convective drying conditions. Eur J Environ Civ Eng, 1-13.
3. 3. Barcík, Š., Gašparík, M., Razumov, E.Y. (2015). Effect of thermal modification on the colour changes of oak wood. Wood Res, 60:385–396
4. 4. Büyüksari, Ü., As, N., Dündar, T., Korkmaz, O. (2017). Micro-mechanical properties of Oak wood and comparison with standard-sized samples. Maderas Cienc y Tecnol, 19:481-494.
5. 5. Divos, F., Divos, P., Divos, G. (2007). Acoustic techniques: from seedling to wood structures. In: Ross R.J, editor. Proceedings of the 15th International Symposium on Nondestructive Testing of Wood, 10-12 September 2007; Duluth, Minnesota, USA; Forest Products Society, pp 3-12.
6. 6. Gerhards, C.C. (1982). Effect of moisture content and temperature on the mechanical properties of wood: An analysis of immediate effects. Wood Fiber, 14:4-36
7. 7. Jiang, J., Lu, J., Zhou, Y., Zhao, Y., Zhao, L. (2014). Compression strength and modulus of elasticity parallel to the grain of Oak wood at ultra-low and high temperatures. BioResources, 9(2):3571-3579.
8. 8. Korkut, D.S., Hiziroglu, S. (2014). Experimental test of heat treatment effect on physical properties of red oak (Quercus falcate Michx.) and southern pine (Pinus taeda L.). Materials (Basel), 7:7314-7323.

9. 9. Korkut, S., Hiziroglu, S. (2009). Effect of heat treatment on mechanical properties of hazelnut wood (Corylus colurna L.). Mater Des, 30:1853-1858. https://doi.org/10.1016/j.matdes.2008.07.009
10. 10. Kubovský, I., Kačíková, D., Kačík, F. (2020). Structural changes of oak wood main components caused by thermal modification. Polymers, 12(2):485
11. 11. Schaffer, E. (1970). Elevated temperature effect on the longitudinal mechanical properties of wood. Ph.D. Thesis, University of Wisconsin, Madison, USA, 1 pp.
12. 12. Sinha, A., Gupta, R., Nairn, J.A. (2010). Effect of heat on the mechanical properties of wood and wood composites. In: Ceccotti, A., editor. Proceedings of the 11th World Conference on Timber Engineering, 20-24 June 2010; Trentino, Italy; Trees and Timber Institute, National Research Council, pp Vol 1:661-668.
13. 13. TS 2472. (2005). Wood - Determination of density for physical and mechanical tests. Turkish Standards Institution, Ankara, 8 p.
14. 14. TS 2478. (2005). Wood-Determination of modulus of elasticity in static bending. Turkish Standards Institution, Ankara, 8 p.
15. 15. Yilmaz Aydin, T., Aydin, M. (2018). Prediction of bending properties of Oriental beech wood exposed to temperature. In: Aydın, İ, and Gezer, E.D., editors. Proceedings of the International Forest Products Congress, 26-29 September 2018; Trabzon, Turkey; Karadeniz Technical University, pp 772-778.