| This thesis presents a study on certain aspects of the modeling of the mechanical behavior of rocksalt. he model SUVIC, developed at École Polytechnique de Montréal, has been used for these works. It is a unified viscoplastic model with kinematic and isotropic hardening and internal variables. This model is recognized to be sufficiently flexible to provide a proper description of the behavior of rocksalt for a wide range of loading conditions.; The model is introduced in a modified more general framework, suitable for the introduction of non-isothermal components. This representation helps in achieving certain thermodynamic verifications related to the dissipative nature of the model. In particular, one can mention the use of a non-singular formulation to describe the behavior of rocksalt at steady state.; This characterization of the steady state conditions is followed by a simplification in the way to express the importance of the saturated values of the internal state variables with respect to the applied stress. A linear formulation, more restrictive than the previous one, is found to be more stable numerically. Certain new elements related to the inclusion of the effects of temperature and the ability to generalize the model in a more classical framework from which certain thermodynamic variables can be inferred, are also presented.; Several experimental aspects are also discussed. A database of laboratory tests on Avery Island rocksalt has been constructed from data available from the literature. These tests illustrate a strong kinematics hardening component. The question of the material constants determination is discussed in details throughout this thesis. An approach providing a preliminary set of constants from experimental results from a particular salt is explained.; The preliminary set of constants is optimized by using certain numerical tools. The identification process starts by the determination of the elastic constants, followed by the determination of the constants describing steady-state conditions (for different temperatures) using a hyperbolic sine formulation. For the transient phase, which is the key of this constant determination exercise, analytical methods are first used for isothermal conditions.; The SUVIC model is also introduced in a finite element code. The use of ZéBuLoN as platform to implement the model is presented in details, in particular with respect to the integration of the local problem with explicit (Runge-Kutta) and implicit (&thetas;) integration methods. Simulations are shown for laboratory tests and hyperstatic problems (thick and thin wall cylinders). (Abstract shortened by UMI.)... |
