| Elastic: | (english) A material or structure is said to behave elastically if it returns to its original geometry upon unloading. |
| Elastic energy: | (english) The energy stored in deformed elastic material (e.g., a watch spring). Elastic energy equals where k is the stiffness, and is the associated deflection. Elastic energy is sometimes called elastic potential energy because it can be recovered when the object returns to its original shape; see potential energy. |
| Elastic limit: | (english) The point beyond which the deformations of a structure or material are no longer purely elastic. |
| Inelastic: | (english) Not surprisingly, the opposite of elastic. A deformation of a structure or material under load is described as inelastic when the deformation remains after the load is removed. The term plastic is often used with the same meaning. |
| Linear: | (english) A structure is said to behave linearly when its the deformation response is directly proportional to the loading (i.e. doubling the load doubles the displacement response). For a material, linear means that the stress is directly proportional to the strain. |
| Linear Elastic: | (english) A force-displacement relationship which is both linear and elastic. For a structure, this means the deformation is proportional to the loading, and deformations disappear on unloading. For a material, the concept is the same except strain substitutes for deformation, and stress substitutes for load. |
| Modulus of elasticity: | (english) The proportional constant between stress and strain for material with linear elastic behavior: calculated as stress divided by strain. Modulus of elasticity can be interpreted as the slope of the stress-strain graph. It is usually denoted as E, sometimes known as Young's Modulus Y, or E-Modulus. |
| Pressure: | (english) Pressure is a similar idea to stress, the force intensity at a point, except that pressure means something acting on the surface of an object rather than within the material of the object. When discussing the pressure within a fluid, the meaning is equivalent to stress. |
| Shear strain: | (english) Strain measuring the intensity of racking in the material. Shear strain is measured as the change in angle of the corners of a small square of material. |
| Shear modulus: | (english) The ratio of shear stress divided by the corresponding shear strain in a linear elastic material. |