LAUSR

Finger joints with standard geometries and adhesives used for joining coniferous wood are not sufficient in terms of strength when gluing beech wood. A numerical model of finger joined beech lamellas was prepared and simulations of tension tests were made. Parametric studies with multiple variables referring to geometrical properties of finger joints and two different types of applied adhesives were performed. The results showed a high influence of the finger joint geometrical parameters. Experimental tests on the tension strength of the finger joints were performed. To validate the numerical model, 20 mm long finger joints were produced and tested. Two types of adhesives were used, MUF and PRF. The finger joints were pressed under two different pressures. Prior to tension testing, the dynamic modulus of elasticity was measured with a strength grading machine and strength grade assignments were made. The influence of joining of the boards on the dynamic modulus of elasticity was analysed. The results of the tension tests of the finger joints showed a clear influence of the finger joint geometry, where highest strengths were obtained with longer and thinner fingers, while the influence of the adhesive seems to decrease with the length of finger joints.