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Rods glued in engineered hardwood products part II: Numerical modelling and capacity prediction

: Grunwald, Cordula; Vallée, Till; Fecht, Simon; Bletz-Mühlendorfer, Oliver; Diehl, Friedemann; Bathon, Leander; Walther, Frank; Scholz, Ronja; Mysliki, Sebastian


International journal of adhesion and adhesives 90 (2019), pp.182-198
ISSN: 0143-7496
ISSN: 1879-0127
Journal Article
Fraunhofer IFAM ()

The second part of this series of two papers presents the modelling and strength prediction of Glued-in Rods (GiR) experimentally investigated in Part I. Unlike what has been documented in previous publications, significant effort was put into extensive modelling of all components (adhesive, wood, and rods), in particular regarding stress components other than shear. Based upon the material modelling, stresses inside the GiR were estimated through Finite-Element Analysis (FEA), which indicated that transverse tensile strength are at least as significant as shear stresses in their magnitude. Both results mitigate previous research findings that focused on shear-dominated failure mechanisms and neglected transverse tensile strength. Combining the material characterization with FEA, and reformulating strength in probabilistic terms, then allowed to perform predictions of joint capacities for all 60 experimentally investigated GiR-configurations. The comparison between predicted and experimental values showed a good agreement wit relative difference amounting to –3% for beech GLT, –2%for oak GLT, and +1%, respectively. Unlike Fracture Mechanics and Cohesive Zone Modelling, necessary parameters were solely obtained independently from the GiR itself, and no single parameter had to be back-fitted on the experimental results of the GiR. Results clearly showed that transverse tensile strength of the wood is at least as important as shear strength for joint capacity of GiR, and that longitudinal strength plays a minor role.