This work considers a mathematical model that describes quasistatic evolution of an elastic 2D bar that may come in frictional contact with a deformable foundation. We present the model and some of its underlying assumptions. In particular, the novelty in the model is that both vertical and horizontal motions are taken into account, which makes it especially useful when frictional contact is concerned. Contact is described with the normal compliance condition and friction with the Coulomb law of dry friction. We introduce a hybrid variational formulation of the problem and a numerical discretization based on a uniform time step and the finite element method in space. The numerical algorithm has been implemented, and we present computer simulations that illustrate the mechanical behavior of the system with emphasis on frictional aspects of the problem.

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The purpose of this talk is primarily to introduce a new methodology to synthesize numerically accurate programs for the Gaussian elimination method in order to solve linear systems coming from mechanical problems. The synthesis is based on program transformation techniques and it is guided in its estimation of accuracy by interval arithmetic that computes the propagation of roundoff errors. Besides a discussion on numerical accuracy issues related to floating-points arithmetics and roundoff errors, we present our approach used to compute the error bound during the resolution process. Finally, some experimental results will be presented to prove the efficiency of our synthesizer tool and show that the specialized produced code to solve the family of systems given in input is far more accurate and faster than the standard implementation of the Gauss method.