Evaluation of the fracture toughness of wood welded connections: Measurement of the energy release rate by the method of experimental compliance

The energy release rates of beech specimens bonded by linear friction welding were determined using double cantilever beam (DCB) tests. The analysis of the results was carried out with the experimental compliance method, which is based on the linear-elastic fracture mechanics. The compliance relation was approximated to a third-order polynomial equation for smoothing and followed by calculation of least squares. This analysis method had not been previously used for glued connections in mode I. It proved to be an ideal method for the results obtained from the study of the energy release rates of the welded joints. The value of the energy release rate GIc obtained is, on average, 106 J/m 2 . The variation in the results is less than for most energy release rates of the wood-adhesive couples studied previously using beech. This proved that this method of measurement of the energy release rate adapts well to DCB wood welded specimens. It is the first time that fracture mechanics is applied to the study of linear friction welded wood joints.