In this study, the elastic properties of 23 specimens of oak timber (Quercus castaneifolia), including the longitudinal modulus of elasticity (MOE), acoustic coefficient (K), and acoustic converting efficiency (ACE) in free vibration using the free-free beam method with different planes of vibration, i.e. tangential (LT) and radial (LR), were studied. These elastic parameters were examined in both sound wood and finger jointed timbers with two different lengths of fingers (5-and 10-mm finger lengths) and individually glued with two different types of adhesives (isocyanate and polyvinyl acetate). Comparing the elastic properties of solid beams with finger jointed beams of oak wood in both (LT) and (LR) planes, 10-mm finger joints with polyvinyl acetate adhesive did not cause any serious change to the studied elastic properties of the beams, while shorter finger length (5 mm) with isocyanate adhesive severely changed the acoustic properties; therefore, beams having longer finger lengths may have enhanced acoustical properties.

In the present study, elastic properties of scarfjointed oak (Quercus castaneifolia) timbers with the application of two different types of adhesives (polyvinyl acetate and isocyanate) were evaluated using free flexural vibration of free-free beam method in different flexural directions of vibration, i.e., tangential and redial directions. Samples were taken from trees of Hyrcanian forests in Iran with nominal dimensions of 20 9 20 9 360 mm 3 . Comparing the results of elastic properties of clear oak wood beams with scarf-jointed samples wood showed that scarf joints with the bonding angles of 70°and 75°, covered by polyvinyl acetate adhesive, did not demonstrate any significant effect on modules of elasticity. Scarf-jointed beams with smaller joint angles (60°and 65°) were considerably weaker or totally unreliable in their moduli of elasticity. It is also shown that the magnitude of effect gets worst by using isocyanate rather than polyvinyl acetate adhesive.

The aim of this paper is to determine the effect of hole diameter (LR Direction) on acoustic performance indicators such as acoustic coefficient and acoustic conversion efficiency of wooden beams using flexural vibration of a free-free bar test.The drilling from 0 to 8 millimetres diameter was made exactly at the middle of the bar, on the node of the second mode of vibration. The results revealed that holes of diameter from 0 to 8 millimeters didn’t cause any sever change on acoustic coefficient and acoustic conversion efficiency when the beam was impacted on both radial and tangential surfaces. Nevertheless, these acoustic properties changed a bit when the beam was impacted on the tangential surface. Thus, the changes of the acoustic coefficient and acoustic conversion efficiency for both radial and tangential impacts were not significant, even with an 8 mm hole. Therefore, hole diameter not only didn’t cause any severe effect on acoustic coefficient and acoustic conversion efficiency but also somewhat increased their values. So, a hole having a relatively small diameter may cause improved acoustical performance of a wooden beam.