Rheology of materials

Rheology is the study of the deformation and flow of matter under the effect of an applied mechanical stress. In the field of materials, this science concerns in particular the following fields

            - Viscoelasticity

            - Plasticity

            - Viscoplasticity

            - Non-Newtonian fluids

In practice, rheology allows the characterization of macroscopic mechanical properties of materials whose behavior escapes the classical theories of the elastic solid and Newtonian fluids (with constant viscosity). Such materials can thus be considered as having an intermediate behavior between the solid and the fluid, between the elastic and the viscous.

The objective of this Teaching Unit (UE) is to allow the students of L3 mechanics to better apprehend certain other teachings of L3 (in particular, the resistance of materials, the mechanics of fluids, the mechanics of the deformable solid and the dimensioning of the structures) as well as to prepare them to better approach future teachings in Master (generalized standard materials, etc).

To this end, this course will expose the different typical mechanical behaviors of different classes of materials (metals, polymers, granular materials, wood, etc.) by relating them to their specific (micro-)structural organizations and composition, which guide their deformation modes. The notions of isotropy, orthotropy, transverse isotropy and total anisotropy will be discussed. In addition, a presentation of the main types of experimental tests (e.g. uni-axial tension, bi-axial tension, etc.; strain hardening, creep, relaxation tests, etc.) will be given.

Rigid solid mechanics

Recommended prerequisites*:

Knowledge of materials and their classification

Final examination

1) Different types of materials

2) Different types of experimental trials

3) Different mechanical behaviors (associated with these experimental tests)

4) Rheological models to represent these behaviors

1. a) Rheological models: The course first explains in a general way the distinctions between solid and fluid behavior, elastic and viscous behavior, by considering the corresponding temporal aspects. An introduction to plasticity (fluid-like deformation of a solid beyond a mechanical stress threshold) is also presented

Then, the main rheological models (and their associated analogical models) are shown as well as their use to determine the corresponding mechanical properties. Finally, the methods to associate these models in series and/or in parallel in order to develop more complex ones are developed.