Assessing the flexural strength changes in decayed wood of Iranian beech (Fagus orientalis) by using of nondestructive stress wave method

The aim of this study was to evaluate sound and decayed wood of Iranian beech (Fagus orientalis) with a nondestructive stress wave method. Wood samples, with dimensions of 9 by 19 by 200 mm were decayed in laboratory soil-bed tests, based on European pre-standard ENV-807. The decay was evaluated by measuring bending dynamic modulus of elasticity (MOEd) and longitudinal dynamic modulus of elasticity (MOEd,l), using a NDT stress wave method after 6, 12, 18 and 24 weeks of exposure. The static modulus of elasticity (MOEs) and percentage of mass loss were also measured at the different stages of exposure. The results show that both static and dynamic MOE measurements provide a more sensitive insight into property changes from fungal degradation compared with mass loss percentages. In this regard MOEd is more reliable compared with MOEd,l. There was also a good correlation (r=0.97) between the MOEs and MOEd for both sound and decayed Iranian beech.