Relationship between the dynamic and static modulus of elasticity in standing trees and sawn lumbers of Paulownia fortune planted in iran

This paper aims to introduce a relationship between the dynamic modulus of elasticity in healthy standing trees of Paulownia fortune (planted in Iran) and the static modulus of elasticity in sawn wood. For this reason, a stress-wave non-destructive testing technique was carried out in longitudinal and transverse directions in 14 trees into two diameter classes (25-31 cm and 32-38 cm) at breast height and in logs at different height of stem to measure the stress wave speed and consequently, dynamic modulus of elasticity. Then, static modulus of elasticity of samples was calculated using 3-point bending tests in the sawn wood. The results revealed that the stress-wave speed and dynamic modulus of elasticity in logs of paulownia are more than those of standing trees in longitudinal direction. Also, the diameter of the tree can significantly affect the stress wave velocity in standing trees and logs of paulownia. Finally, a high correlation coefficient exists between static modulus of elasticity and dynamic modulus of elasticity (r= 0.68) in this tree. Keywords: Modulus of elasticity, non-destructive testing, Paulownia, standing trees, stress-wav