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In this Note we present an approach to determine the local minima of a specific class of minimization problems. Attention is focused on the inextensibility condition of flexible rods expressed as a nonconvex constraint. Two algorithms are derived from a special splitting of the Lagrangian into the difference of two convex functions (DC). They are compared to the augmented Lagrangian methods used in this context. These DC formulations are easily extended to contact problems and applied to the determination of confined buckling shapes. To cite this article: P. Alart, S. Pagano, C. R. Mecanique 330 (2002) 819–824. [Copyright &y& Elsevier]

In this Note we study a parameter identification problem associated with a two-dimensional mechanical problem. In a first part, the experimental technique of determining the displacement field is presented. The variational method proposed herein is based on the minimization of a separate convex functional which leads to the reconstruction of the elastic tensor and the stress field. These two reconstructed fields are continuous and piecewise linear on a triangulation of the two-dimensional problem. Some numerical and experimental examples are presented to test the performance of the algorithm. To cite this article: G. Geymonat et al., C. R. Mecanique 330 (2002) 403–408. [Copyright &y& Elsevier]

Abstract: This Note presents criteria on the artificial compliance due to intrinsic cohesive zone models. A homogenized model is proposed for a collection of cohesive zones embedded between each mesh of a finite element-type discretization (cohesive-volumetric approach). The overall elastic behavior of this cohesive-volumetric medium is obtained as a function of the local properties and the mesh size. For an isotropic discretization, a criterion on the cohesive stiffnesses is derived: the additional compliance inherent to intrinsic cohesive zone models is bounded by lower value. [Copyright &y& Elsevier]