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 Iranianbeech (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 measuringbending dynamic modulus of elasticity (MOEd) and longitudinal dynamicmodulus of elasticity (MOEd,l), using a NDT stress wave method after 6, 12, 18 and24 weeks of exposure. The static modulus of elasticity (MOEs) and percentage ofmass loss were also measured at the different stages of exposure. The results showthat both static and dynamic MOE measurements provide a more sensitive insightinto property changes from fungal degradation compared with mass losspercentages. In this regard MOEd is more reliable compared with MOEd,l. Therewas also a good correlation (r=0.97) between the MOEs and MOEd for both soundand decayed Iranian beech.