Modélisation de fissures elliptiques internes par hybridation de fonctions de poidsEmbedded elliptical cracks modeling with hybridization of weight functions

A method improving the evaluation of the stress intensity factor by hybridization of two weight functions is presented and applied to embedded elliptical cracks under various loadings. The hybridization consists in using one or the other function in the zone of the crack where it is the most efficient. The delimitation of the two zones is achieved after optimizing the axes ratio and the curvature radius of the crack. During this optimization we seek to reduce the effects of the singularities present in the weight functions as well as to take better into account the influence of the ellipse curvature. To cite this article: B. El Khalil Hachi et al., C. R. Mecanique 334 (2006).     

Rigidité à la torsion d'un cylindre présentant une double périodicité

The objective of the present Note is to estimate the equivalent torsion rigidity modulus for a cylinder whose cross-section Σ exhibits a periodical distribution of porous zones Σ_P. Taking into account a second, finer, periodical distribution of pores in Σ_P, we have to use the homogenization method in a biperiodical context. However, the contrast of scales at the interfaces between Σ_P and the compact part Σ_C of Σ, requires some subtle fitting up of this method. Finally, we point out the existence of boundary layers around the interfaces ∂Σ_P and we estimate the weakening of the torque rigidness. To cite this article: M'B. Taghite et al., C. R. Mecanique 334 (2006).