Characterization of mode II delamination behaviour of poplar plywood and LVL

• Published in: Theoretical and applied fracture mechanics 2024-06, Vol.131, p.104354, Article 104354
• Main Authors: Hadiji, H., Serra, J., Curti, R., Gebrehiwot, D., Castanié, B.
• Format: Article
• Language: English
• Subjects: 4ENF; Engineering Sciences; Interlaminar fracture toughness; LVL; Mode II; Plywood; R-curve
• ISSN: 0167-8442; 1872-7638
• DOI: 10.1016/j.tafmec.2024.104354

The aim of this work was to characterize the interlaminar fracture toughness of poplar laminate veneer lumbers (LVL) under mode II loading. To this end, the Four-point End Notched Flexure test (4ENF) was chosen, and crack propagation was continuously monitored during the test using a stereo-correlation set-up. The R-curve was then obtained by a compliance calibration method, expressing the evolution of the critical strain energy release rate as a function of the crack length for the tested specimens. Two different interfaces were investigated, with the interfacial fibre orientations of 0°/90° and 0°/0°. The results show that the interlaminar fracture toughnesses are about 2.2 and 2.5 kJ/m2 for interfaces 0°/0° and 0°/90°, respectively. These values are higher than those of carbon-epoxy laminates. Fracture surface morphologies were analysed to understand the effect of fibre orientation on the fracture toughness. Finally, the fracture toughness was calculated with a compliance-based beam method, and good agreement was found between the two methods.