Inelastinen

Inelastinen is a Finnish term that translates to not elastic and is used in physics and materials science to describe processes in which a material or system does not return fully to its original shape after a deforming force is removed. In such cases some energy is transformed into other forms, such as heat, sound, or permanent deformation, rather than being fully stored as elastic potential energy.

In the context of collisions, an inelastic collision is one in which kinetic energy is not conserved, even though momentum is conserved. The degree of inelasticity is described by the coefficient of restitution, e, where 0 ≤ e < 1. When e = 1 the collision is perfectly elastic; as e decreases, more energy is dissipated through deformation, heating, or other internal processes. A completely inelastic collision corresponds to e = 0, where the colliding bodies move together after impact.

Inelastic deformation refers to irreversible changes in shape under load. When a material yields and flows plastically, it does not return to its original form once the load is removed. This behavior is characterized by a yield point, plastic deformation, and energy loss visible as hysteresis in stress–strain responses. Viscoelastic materials exhibit time-dependent inelastic responses, combining both viscous and elastic elements.

Applications and measurement include crash safety design, impact testing, and material characterization. Engineers assess inelastic behavior through impact tests, indentation or tensile experiments, and analyses of energy dissipation, aiding in the selection of materials for energy absorption and durability.