Amir Homan Hemmasi; mostafa kohantorabi
Abstract
In this study the relationship between dynamic modulus of elasticity from longitudinal vibration method with static modulus of elasticity and bending strength in two directions: the Parallel machine direction and machine direction have been investigated. For this purpose 4 plates ...
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In this study the relationship between dynamic modulus of elasticity from longitudinal vibration method with static modulus of elasticity and bending strength in two directions: the Parallel machine direction and machine direction have been investigated. For this purpose 4 plates of particleboard with dimensions 124× 90 ×1.6 cm (length× width× thickness) were selected and free longitudinal vibration test in PMD and MD were performed on each plates. After that the primary plates were cut to four plates with dimensions 62× 44 ×1.6 cm (length× width× thickness) and longitudinal vibration test in PMD and MD were performed on each plates again. Finally each plates were cut to the beams with dimensions 36× 1.6 ×1.6 cm and longitudinal vibration test and and static bending test were performed on them. The results show that good correlation between dynamic modulus of elasticity from longitudinal vibration test and static modulus of elasticity and bending strength (result of beams extracted from each plates) in both size of plates in two size (124× 90 ×1.6 and 62× 44 ×1.6 cm) and beams extracted from each plates in two directions (PMD and MD). In addition there was good correlation between dynamic modulus of elasticity of longitudinal vibration from two size plates (124× 90 ×1.6 and 62× 44 ×1.6 cm). When the samples smaller than primary plates, the dynamic modulus of elasticity values were increased, that it due to the diffusion of waves in samples with larger dimensions. In general, according to results of this research it can be concluded that by applying the appropriate correction factors, longitudinal vibration method an efficiency method for calculation of dynamic and static modulus of elasticity and estimate of the modulus of rupture in plates in full sized.
Physics and Mechanical Wood
Habibalah Arabtabar; Abdolrahman Hosseinzadeh; Ali Rezanezhad; Ghanbar Ebrahimi
Abstract
The economical importance of railroads and their development in Iran have been caused those annually 500000 wood sleepers to be required, if sleepers are to be maintained in suitable condition. However, the wood resources are also limited, specially producing roadbeds with high classes. For conservation ...
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The economical importance of railroads and their development in Iran have been caused those annually 500000 wood sleepers to be required, if sleepers are to be maintained in suitable condition. However, the wood resources are also limited, specially producing roadbeds with high classes. For conservation of natural resources (Forests) we need to use logs with lower classes as well. The process of lamination can permits manufacturing sleepers from small logs. Therefore, the manufacturing of two half laminated ties (interface vertical or horizontal) were lower. As in Iranian beech is usually used for manufacturing sleepers, in this study it was also utilized to make dowel-laminated sleepers. The results of this study showed that, the processes of impregnation of dowel-laminated sleepers with preservative (Creosote) and depth of its penetration were better established than in usual sleepers. Laboratory test indicated that modulus of elasticity of two half laminated - vertical sleepers was the same as the usual sleepers but this resistance in two half laminated - horizontal sleepers was decreased. Finally after five years exposure under extensive service, tests no failures in dowel-laminated sleepers especially in vertical shapes were observed.
