8/22/2023 0 Comments Define viscosity and elasticity![]() ![]() ![]() ![]() The elasticity of materials is described by a stress–strain curve, which shows the relation between stress (the average restorative internal force per unit area) and strain (the relative deformation). Young's modulus and shear modulus are only for solids, whereas the bulk modulus is for solids, liquids, and gases. For instance, Young's modulus applies to extension/compression of a body, whereas the shear modulus applies to its shear. The various moduli apply to different kinds of deformation. There are various elastic moduli, such as Young's modulus, the shear modulus, and the bulk modulus, all of which are measures of the inherent elastic properties of a material as a resistance to deformation under an applied load. When an elastic material is deformed due to an external force, it experiences internal resistance to the deformation and restores it to its original state if the external force is no longer applied. The material's elastic limit or yield strength is the maximum stress that can arise before the onset of plastic deformation. The SI unit of this modulus is the pascal (Pa). In engineering, the elasticity of a material is quantified by the elastic modulus such as the Young's modulus, bulk modulus or shear modulus which measure the amount of stress needed to achieve a unit of strain a higher modulus indicates that the material is harder to deform. This is an ideal concept only most materials which possess elasticity in practice remain purely elastic only up to very small deformations, after which plastic (permanent) deformation occurs. This is known as perfect elasticity, in which a given object will return to its original shape no matter how strongly it is deformed. Hooke's law states that the force required to deform elastic objects should be directly proportional to the distance of deformation, regardless of how large that distance becomes. For rubbers and other polymers, elasticity is caused by the stretching of polymer chains when forces are applied. When forces are removed, the lattice goes back to the original lower energy state. In metals, the atomic lattice changes size and shape when forces are applied (energy is added to the system). The physical reasons for elastic behavior can be quite different for different materials. This is in contrast to plasticity, in which the object fails to do so and instead remains in its deformed state. Solid objects will deform when adequate loads are applied to them if the material is elastic, the object will return to its initial shape and size after removal. In physics and materials science, elasticity is the ability of a body to resist a distorting influence and to return to its original size and shape when that influence or force is removed. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |