A relationship between non-exponential stress relaxation and delayed elasticity in the viscoelastic process in amorphous solids: Illustration on a chalcogenide glass

Yann Gueguen (1) , Vincent Keryvin (2, 1) , Tanguy Rouxel (1) , Mickaël Le Fur (1) , Hervé Orain (1) , Bruno Bureau (3) , Catherine Boussard-Plédel (3) , Jean-Christophe Sangleboeuf (3)

1 IPR - Institut de Physique de Rennes
2 LIMATB - Laboratoire d'Ingénierie des Matériaux de Bretagne
3 ISCR - Institut des Sciences Chimiques de Rennes

Inorganic glasses are viscoelastic materials since they exhibit, below as well as above their glass transition temperature, a viscoelas-tic deformation under stress, which can be decomposed into a sum of an elastic part, an inelastic (or viscous) part and a delayed elastic part. The delayed elastic part is responsible for the non-linear primary creep stage observed during creep tests. During a stress relaxation test, the strain, imposed, is initially fully elastic, but is transformed, as the stress relaxes, into an inelastic and a delayed elastic strains. For linear viscoelastic materials, if the stress relaxation function can be fitted by a stretched exponential function, the evolution of each part of the strain can be predicted using the Boltzmann superposition principle. We develop here the equations of these evolutions, and we illustrate their accuracy by comparing them with experimental evolutions measured on GeSe 9 glass fibers. We illustrate also, by simple equations, the relationship between any kind of relaxation function based on additive contribution of different relaxation processes and the delayed elastic contribution to stress relaxation: the delayed elasticity is directly correlated to the dispersion of relaxations times of the processes involved during relaxation.

Mots clés: stretch exponent; linear viscoelasticity; chalcogenide glasses; delayed elasticity; anelasticity

Domaines: Mécanique [physics]; Physique [physics]

Yann Gueguen, Vincent Keryvin, Tanguy Rouxel, Mickaël Le Fur, Hervé Orain, et al.. A relationship between non-exponential stress relaxation and delayed elasticity in the viscoelastic process in amorphous solids: Illustration on a chalcogenide glass. Mechanics of Materials, 2015, 85, pp.47-56. ⟨10.1016/j.mechmat.2015.02.013⟩. ⟨hal-01153240⟩