Fatigue life and durability of wood material under mixed-mode fracture with viscoelastic and moisture-dependent effects: A finite element modeling approach

Résumé fourni par la source

Fatigue and durability assessment of wooden structural components remains a major scientific challenge owing to the intrinsic complexity of wood behavior, particularly its pronounced anisotropy, mixed-mode crack propagation mechanisms, viscoelastic response, and strong sensitivity to environmental variations. This paper delves into a numerical framework combining fracture and fatigue modeling under mixed-mode loading, while simultaneously accounting for anisotropy, viscoelasticity, and moisture variations, in order to predict the service life of wood structures subjected to cyclic hygro-mechano-viscoelastic loading conditions. The energy release rate, which constitutes the key driving parameter of the analysis, is evaluated through the invariant integral A θ visco , enabling the treatment of viscoelastic mixed-mode fracture under variable environmental conditions while ensuring a rigorous separation of elementary modal contributions. This energy release rate is subsequently introduced into the Paris law to estimate fatigue life through crack growth integration. Several cyclic loading scenarios are investigated, including purely mechanical cycles, coupled hygromechanical loading, as well as viscoelastic and mechano-sorptive solicitations. A comparative analysis of the predicted fatigue lives highlights the influence of hydric cycles on wood durability, particularly when coupled with delayed deformation mechanisms. The results emphasize the necessity of developing predictive fracture-fatigue models incorporating time-dependent and hygroscopic phenomena in order to improve durability assessment, structural diagnosis, and long-term monitoring of timber structures.

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