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Perfect plasticity is a property of materials to undergo irreversible deformation without any increase in stresses or loads. Plastic materials that have been hardened by prior deformation, such as cold forming, may need increasingly higher stresses to deform further. Generally, plastic deformation is also dependent on the deformation speed, i.e ...
A property having a fixed value for a given material or substance is called material constant or constant of matter. [1] (Material constants should not be confused with physical constants, that have a universal character.) A material property may also be a function of one or more independent variables, such as temperature. Materials properties ...
An alternative approach is to add a strain rate dependence to the yield stress and use the techniques of rate independent plasticity to calculate the response of a material. [ 4 ] For metals and alloys , viscoplasticity is the macroscopic behavior caused by a mechanism linked to the movement of dislocations in grains , with superposed effects ...
Plastic deformation of a thin metal sheet. Flow plasticity is a solid mechanics theory that is used to describe the plastic behavior of materials. [1] Flow plasticity theories are characterized by the assumption that a flow rule exists that can be used to determine the amount of plastic deformation in the material.
Malleability, a similar mechanical property, is characterized by a material's ability to deform plastically without failure under compressive stress. [8] [9] Historically, materials were considered malleable if they were amenable to forming by hammering or rolling. [10] Lead is an example of a material which is relatively malleable but not ductile.
A solid is a material that can support a substantial amount of shearing force over a given time scale during a natural or industrial process or action. This is what distinguishes solids from fluids, because fluids also support normal forces which are those forces that are directed perpendicular to the material plane across from which they act and normal stress is the normal force per unit area ...
When the stress state lies on the surface the material is said to have reached its yield point and the material is said to have become plastic. Further deformation of the material causes the stress state to remain on the yield surface, even though the shape and size of the surface may change as the plastic deformation evolves.
The properties are better studied using tensor-valued constitutive equations, which are common in the field of continuum mechanics. For non-Newtonian fluid's viscosity , there are pseudoplastic , plastic , and dilatant flows that are time-independent, and there are thixotropic and rheopectic flows that are time-dependent.