The interplay of material and geometric instabilities in large deformation s of viscous rock
Résumé
We analyse folding phenomena in layered viscous rock in which we assume that the thickness of each layer is much smaller than characteristic structural dimensions. We derive constitutive relations and apply a computational simulation scheme suitable for problems involving very large deformations of layered viscous materials. We then consider buckling instabilities in a finite, rectangular domain. Embedded within this domain, parallel to the longer dimension we consider a stiff, layered beam under compression. We analyse folding up to 40% shortening. The effect of layering manifests itself in that appreciable buckling instabilities are obtained at much lower viscosity ratios (1:10) than required for the buckling of isotropic beams (roughly 1:500). The wavelength induced by the initial harmonic perturbation of the layer orientation seems to be persistent. A linear instability analysis is conducted to clarify the numerical results and also to examine the potential role of couple stresses on the folding process
Origine : Fichiers produits par l'(les) auteur(s)