Nondestructive evaluation of defects (face to face and end to end joints) with polyvinyl acetate applied adhesive using vibration method

In this research, influences of defects in end to end and face to face joints have been investigated. 21 poplar specimens and 42 beech specimens with different type of joints (end to end face to face) have been used. Polyvinyl acetate adhesive applied and bending vibration tests have been carried out to perform elastic properties of specimens. No significant differences were observed comparing elastic modulus and acoustical coefficient of defective joints and solid beams, while the adhesion defect in this joint increased the damping factor and decreased the acoustic conversion efficiency. The results also indicate that defect in end to end joints has significant impact on the elastic modulus, acoustical coefficient, damping factor and acoustic conversion efficiency. Totally, variation on acoustic conversion efficiency as an effectively factor could be used for detection and extent of the defects in end to end and face to face joints before use and at service time.