Hubert Maigre

An exact inversion formula from determining a planar fault from boundary measurements

This paper considers the inverse problem of determining a timedependent slip fault which releases shear stress elastically. The input data are the accelerations measured on the free external surface. A new formulae for determining explicitly the geometry of the planar fault is proposed. Potential applications to real earthquakes are discussed.

Follow-up of a panel restoration procedure through image correlation and finite element modeling

Conservation of paintings of Cultural Heritage on wood panels could gain from using tools of wood science and structural mechanics. Indeed, with a virtual model, prediction of an artwork behavior for various scenarii could help for decision on conservation or restoration acts. Since each artwork is a particular case, it requires an identification step to nurture the model. In this article, we are concerned with a particular restoration act: the partial replacement of a cradle. This study couples an experimental approach (3D stereo-correlation) and a numerical approach (finite elements). The experimental part concerns an optical non-invasive form measurement with digital image correlation, using a projected speckle pattern on the painted panel, with luminance compensation. The numerical part concerns stress evaluation, once the model and the experiments are compared using a geometric mapping and a spatial projection of discrete fields. Using modeling and identification, the simulation attempts to recover the residual stresses in the panel, and allows testing several restoration conditions.

2D X-FEM Simulation of Dynamic Brittle Crack Propagation

The application of X-FEM technique to the prediction of two dimensional dynamic brittle crack growth is presented in this paper. The method is known to guarantee exact energy conservation in case of crack propagation and it is applied to the simulation of one dynamic crack propagation experiment submitted to a mixed mode loading and showing stop and restart of a crack.

On the Growth, the Arrest and the Restart of a Crack during a Dynamic Brittle Fracture Experiment

Our purpose is to propose a methodology for assessing dynamic crack propagation laws under mixed-mode loading. Dynamic brittle fracture experiments are performed on polymethylmethacrylate (PMMA) in which mode combination changes and crack arrest phases occur. Then, these experiments are numerically reproduced by using the eXtended Finite Element Method (X-FEM) in order to validate the algorithms and the criteria assumed.