جستجوی مقالات مرتبط با کلیدواژه « تیمار آب گرمایی » در نشریات گروه « کشاورزی »

  Acoustic property as one of the special characteristics of wood is widely used in making musical instruments. Thus examining acoustic property of wood and factors affecting its improvement is of vital importance. Furthermore, modifying the characteristics of wood with environmentally friendly methods has become increasingly important recently. In the current study, two wood species native to north of Iran that is Beech (Fagus orientalis L.) and Maple (Acer velutinum) were examined in terms of their acoustic properties. Samples were also treated under hydrothermal treatment. The effects of hydrothermal treatment on acoustic properties of samples were measured with free-free flexural vibration method. In order to examine the acoustic properties of two wood species of Beech and Maple, samples in the dimensions of 360 (longitudinal) × 20 (radial) × 20 (tangential) mm were cut according to ISO 3129 standard. Hydrothermal treatment at 150 ° C for 5 hours was applied on samples. Acoustic properties of the treated samples such as modulus of elasticity, damping of vibration, wave velocity, quality of sound, acoustical coefficient and acoustical conversion efficiency were evaluated in two directions of Longitudinal-Radial and Longitudinal-Tangential. Acoustic properties were compared with control samples. The results of this study showed that hydrothermal treatment of wood has a significant effect on improving the evaluated acoustic properties except for the modulus of elasticity and acoustical coefficient factor in comparision with control samples. In general, the greatest effect was observed on mortality hydrothermal treatment of wood, the quality of sound, and acoustical conversion efficiency in species of Maple. The results also indicated that there was no significant difference between the acoustic properties in two directions of Longitudinal-Radial and Longitudinal-Tangential in the treated samples. The effect of hydrothermal treatment on improving acoustic properties of the samples could be due to the withdrawal of water soluble extractives in samples with cleaning material accumulated in vessel ducts, fiber and other stractural elements of wood, as well as increased dimensional stability during treatment in treated samples. According to the results of this study, the hydrothermal treatment of wood species, especially Maple species can be used in manufacturing sound-boards as well as resonator boxes of musical instruments such as Xylophones, Violin, and the Iranian Santour.
Keywords: Hydrothermal treatment, Acoustic properties, Musical instruments, Flexural vibration, Extractives.
Keywords: Hydrothermal treatment, Acoustic properties, Musical instruments, Flexural vibration, Extractives.
Keywords: Hydrothermal treatment, Acoustic properties, Musical instruments, Flexural vibration, Extractives

The objective of this study was to investigate the influence of hydrothermal treatment of walnut (Juglans regia) and caucasian elm (Zelkova Carpinifolia) wood species on their acoustic properties in radial and tangential directions. For this purpose، specimens were prepared with dimensions of 360 (L) ×20 (R) ×20 (T) mm. Heat treatments in water medium were performed at 150ºC for 5 hours. Acoustic properties of specimens (specific modulus of elasticity، damping، acoustical coefficient، acoustical conversion efficiency and wave velocity) measured by free flexural vibration on a free-free bar method. Properties of treated specimens compared with control specimens. Result showed that hydrothermal treatment improved all acoustic properties of specimens. Acoustic properties of radial and tangential surfaces of walnut wood did not show significant difference; while in caucasian elm significant differences obtained between radial and tangential surface properties. Generally، better acoustic properties achieved in tangential direction of heat-treated Caucasian elm species. So، it is recommended as a suitable specimen to be used in making the sound-boards of musical instruments such as Iranian Santour and Xylophones and also resonator boxes.

Heat treatment of wood is an effective method to improve the dimensional stability and durability against biodegradation. Heat treatments of beech wood in 2 different mediums (hot water and steam) at 180ºC were compared by physical، mechanical and anatomical properties. Mass loss in hydrothermally treated wood was higher than hygrothermally treated specimens. Mechanical properties (MOR and MOE) were decreased in both mediums، but strength loss was higher for hygrothermal treated samples. Anatomical changes were investigated by means of a light microscopic analysis. Beech was sensitive to collapse of the vessels in both mediums. In treated beech، radial cracks were observed near the rays both in hydro and hygrothermal treatments. Depletion of extractives on the cell walls and deformation of libriform fibers near the vessels were also observed.