One-dimensional discrete formulation of a hygrolock model for wood hygromechanics

Julien Colmars (1) , Frédéric Dubois (2) , Joseph Gril (1)

1 BOIS - Bois
2 GEMH - Groupe d'Etudes des Matériaux Hétérogènes

a new 1D discrete formulation of hygrolock models is proposed for modeling wood time-dependent behavior. This discrete formulation is compared to an integral formulation presented in a previously published paper. Simulations with various humidity cycles are performed under constant stress (creep) or constant strain (relaxation) using first a hygrolock spring and then a generalized Kelvin-Voigt model with a time-spectral distribution of hygrolocks springs. The discrete formulation presented here, based on original idea of mixed series/parallel rheological model, is shown to be very practical for implementation in scientific numerical codes. In order to compensate a lack of complete data-set on wood material, a generic time and moisture-dependent material is proposed to compare the various models: this dataset could be re-used in other studies. Finally the relevance of hygrolock models for wood time-dependent behavior is discussed: it appears that hygrolock models suits well to the upper part of wood hygroscopic domain, whereas further hypothesis should be tested for dry domain. A judicious choice in moisture activation of material parameters, combined with the blocking effect of hygrolock, agree with recent experimental results on simplifying the description of so-called ++ effect.

Mots clés: hygrolock; wood; mechanosorption; moisture activated creep

Domaines: Mécanique des matériaux [physics.class-ph]

Julien Colmars, Frédéric Dubois, Joseph Gril. One-dimensional discrete formulation of a hygrolock model for wood hygromechanics. Mechanics of Time-Dependent Materials, 2014, 18, pp.309 - 328. ⟨10.1007/s11043-013-9229-x⟩. ⟨hal-01084665⟩