Relationship between the acoustic emission and the strain field in finger joints of engineered wood products for construction

The use of Engineered Wood Products (EWPs) for buildings is becoming very popular because they favor decarbonization in the construction sector and improve the performance and mechanical properties of solid timber. Finger joint technology makes it possible to remove the natural defects of timber (knots, splits, decay areas, etc.), providing for clearer timber and the manufacture of larger structural elements. Nowadays, glued laminated timber (GLT) and cross laminated timber (CLT) are the most used products, suitable even for tall buildings. The finger joints —given the adhesive used and the increased friction surface due to their geometry— allow stress to be transferred efficiently between the joined lamellae, making them behave mechanically almost like a single piece of solid timber. The quality control of these products is therefore crucial. In this work, the longitudinal and transverse strain fields in samples with finger joints, measured by means of the Digital Image Correlation (DIC) technique, are compared with the acoustic emission waves released when the sample is subjected to tensile stress. It is shown that there is a very close correlation between the two, meaning that the acoustic emission technique can be considered a promising tool for the quality control of these structural joints.