Shear strengthIn engineering, shear strength is the strength of a material or component against the type of yield or structural failure when the material or component fails in shear. A shear load is a force that tends to produce a sliding failure on a material along a plane that is parallel to the direction of the force. When a paper is cut with scissors, the paper fails in shear. In structural and mechanical engineering, the shear strength of a component is important for designing the dimensions and materials to be used for the manufacture or construction of the component (e.
Essai de compressionUn essai de compression mesure la résistance à la compression d'un matériau sur une machine d'essais mécaniques suivant un protocole normalisé. Les essais de compression se font souvent sur le même appareil que l'essai de traction mais en appliquant la charge en compression au lieu de l'appliquer en traction. Pendant l'essai de compression, l'échantillon se raccourcit et s'élargit. La déformation relative est « négative » en ce sens que la longueur de l'échantillon diminue.
Contrainte (mécanique)vignette|Lignes de tension dans un rapporteur en plastique vu sous une lumière polarisée grâce à la photoélasticité. En mécanique des milieux continus, et en résistance des matériaux en règle générale, la contrainte mécanique (autrefois appelée tension ou « fatigue élastique ») décrit les forces que les particules élémentaires d'un milieu exercent les unes sur les autres par unité de surface. Ce bilan des forces locales est conceptualisé par un tenseur d'ordre deux : le tenseur des contraintes.
Burgers vectorIn materials science, the Burgers vector, named after Dutch physicist Jan Burgers, is a vector, often denoted as b, that represents the magnitude and direction of the lattice distortion resulting from a dislocation in a crystal lattice. The vector's magnitude and direction is best understood when the dislocation-bearing crystal structure is first visualized without the dislocation, that is, the perfect crystal structure.
Cross slipIn materials science, cross slip is the process by which a screw dislocation moves from one slip plane to another due to local stresses. It allows non-planar movement of screw dislocations. Non-planar movement of edge dislocations is achieved through climb. Since the Burgers vector of a perfect screw dislocation is parallel to the dislocation line, it has an infinite number of possible slip planes (planes containing the dislocation line and the Burgers vector), unlike an edge or mixed dislocation, which has a unique slip plane.
Crystallographic databaseA crystallographic database is a database specifically designed to store information about the structure of molecules and crystals. Crystals are solids having, in all three dimensions of space, a regularly repeating arrangement of atoms, ions, or molecules. They are characterized by symmetry, morphology, and directionally dependent physical properties. A crystal structure describes the arrangement of atoms, ions, or molecules in a crystal.
Yield (engineering)In materials science and engineering, the yield point is the point on a stress-strain curve that indicates the limit of elastic behavior and the beginning of plastic behavior. Below the yield point, a material will deform elastically and will return to its original shape when the applied stress is removed. Once the yield point is passed, some fraction of the deformation will be permanent and non-reversible and is known as plastic deformation.
Stress–strain analysisStress–strain analysis (or stress analysis) is an engineering discipline that uses many methods to determine the stresses and strains in materials and structures subjected to forces. In continuum mechanics, stress is a physical quantity that expresses the internal forces that neighboring particles of a continuous material exert on each other, while strain is the measure of the deformation of the material. In simple terms we can define stress as the force of resistance per unit area, offered by a body against deformation.
PseudoelasticityPseudoelasticity, sometimes called superelasticity, is an elastic (reversible) response to an applied stress, caused by a phase transformation between the austenitic and martensitic phases of a crystal. It is exhibited in shape-memory alloys. Pseudoelasticity is from the reversible motion of domain boundaries during the phase transformation, rather than just bond stretching or the introduction of defects in the crystal lattice (thus it is not true superelasticity but rather pseudoelasticity).
Tenseur des contraintesLe tenseur des contraintes est un tenseur d'ordre 2 utilisé en mécanique des milieux continus pour caractériser l'état de contrainte, c'est-à-dire les efforts intérieurs mis en jeu entre les portions déformées d'un milieu. Le terme a été introduit par Cauchy vers 1822. Comme les efforts intérieurs sont définis pour chaque surface coupant le milieu (on parle d'ailleurs également d'efforts surfaciques), le tenseur est défini localement, en chaque point du solide. L'état de contrainte du solide est donc représenté par un champ tensoriel.
