Modulus of elasticity in scarf-jointed wooden beams: a case study with polyvinyl acetate and isocyanate adhesives

Abstract

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.

Quality Assessment of Scarf Joints Considering the Acoustic Parameters: A Nondestructive Approach

“…As theoretically assumed and confirmed by previous research findings (Herak et al 2009;Hemmasi et al 2014;Roohnia et al 2014), considering the steepest angle (75°), the same trend was observed: a significant difference in the performance of PVAc and isocyanate glued samples in different planes of vibration, comparing the acoustical properties of the solid and jointed samples.…”

“…Taking into account the previous findings regarding the influence of adhesives on elastic properties of joints Roohnia et al 2014), it was confirmed that the flexural vibration method is sensitive enough for evaluating the acoustical performance of scarf joints. The best performance of the joints was found to be at scarf of 75°.…”

“…Considering the importance of acoustical properties of scarf joints, numerous research studies have been completed and significant progress has been made (Deng et al 2014;Roohnia et al 2014). Herak et al (2009) studied the mechanical properties of scarf joints and evaluated the influence of joint slope on the mechanical properties and found that scarves of 60° and 75° were the most efficient slopes for joints of spruce wood.…”

“…The effect of joint angles on mechanical properties of wood has been evaluated by other studies. Roohnia et al (2014) studied the elastic modulus in the acoustic properties of scarf-jointed wooden beams with different cutting angles (60°, 65°, 70°, and 75°); the best performance of studied joints was detected at 75° scarf joints.…”

Structural performance evaluation of finger-jointed rubberwood manufactured by factories in Thailand

“…The jointed lumber pieces are used for the production of engineered wood products (Gong et al 2014;Fredriksson et al 2015;Ahmad et al 2017;Lara-Bocanegra et al 2017). Many types of end joints have been used for joining wood such as the scarf joint, butt joint, and finger joint (Jokerst 1981;Roohnia et al 2014). The finger joint is mostly used for joining wood for structural purposes (Jokerst 1981;Frihart and Hunt 2010).…”