I3.6/A3.6 GPS - Transferts thermiques
Les transferts thermiques sont les mécanismes par lesquels la chaleur se déplace d'un corps à un autre.
Il existe trois types de transferts thermiques :
- la conduction
- la convection
- la radiation.
La conduction se produit lorsque la chaleur se déplace à travers un matériau solide en raison de collisions entre les molécules.
La convection se produit lorsque la chaleur se déplace à travers un fluide en mouvement.
La radiation se produit lorsque la chaleur se déplace sous forme d'ondes électromagnétiques, comme la lumière.
Les facteurs qui influencent les transferts thermiques comprennent la température, la surface de contact, la distance, la conductivité thermique et la convection.
Les matériaux et les surfaces peuvent également être conçus pour minimiser ou maximiser les transferts thermiques.
Mécanique des Milieux Continus
Continuum mechanics is a mathematical framework for studying the transmission of force through and deformation of materials of all types. The goal is to construct a framework that is free of special assumptions about the type of material, the size of deformations, the geometry of the problem, and so forth. Of course, no real materials are actually continuous. We know from physics and chemistry that all materials are formed of discrete atoms and molecules. Even at much larger size scales, materials may be composed of distinct components, e.g., grains of sand or platelets of blood. Nevertheless, continuum mechanics deals with the study of the macroscopic behavior of materials disregarding their microscopic structure. We think of the material as being continuously distributed throughout some region of space. At any instant of time, every point in the region is the location of what we refer to as a particle of the material. It is then possible to define quantities such as density, displacement, velocity and so on, as continuous (or at least piecewise continuous) functions of position. This procedure is found to be satisfactory provided that we deal with bodies whose dimensions are large compared with the characteristic lengths (for example interatomic spacings in a crystal, or mean free paths in a gas) on the microscopic scale. The microscopic scale need not be of atomic dimensions; it is possible, for example, to apply continuum mechanics to a granular material such as sand, provided that the dimensions of the region considered are large compared with those of an individual grain. Although there are certainly problems for which it is necessary to take into account the discrete nature of materials, the ultimate justification for using continuum mechanics is that predictions are often in accord with observations and measurements.
The three basic components of continuum mechanics are kinematics, conservation (balance) laws and constitutive equations. The kinematics component describes the geometry of motion and deformation of a continuum body, without considering the cause of motion or deformation. The conservation laws expresses how external effects influence the motion of a continuum body. These laws are universal meaning that they apply equal to all materials. Finally, the constitutive equations describe the material behavior of particular material or classes of materials (e.g., elastic solids, viscous fluids, viscoplastic materials and so on). The formulation of constitutive equations is essentially a matter of experimental observations, but a theoretical framework is needed in order to devise suitable experiments and to interpret experimental results.
I3 - TD TP Mécanique et CAO [LILLE]
Série de 3 TP gravitant autour de :
- la définition cinématique
- la résolution de problèmes statiques et/ou cinématiques
- la résistance des matériaux (méthode classique et numérique)
- la conception de produit (plusieurs méthodes d'obtention)