Fließbereichs

Fließbereich (Genitiv Fließbereichs) is a term used in German-language technical literature to denote the flow region or flow domain within a material or system. It refers to the spatial area where the material undergoes flow, i.e., plastic or viscous deformation, under the prevailing conditions of stress, temperature, and time.

The concept appears across several disciplines, including continuum mechanics, rheology, metallurgy, and geoscience. In metallurgy and metal forming, the Fließbereich describes the zones where plastic flow occurs once the material yields, as described by constitutive models that specify a nonzero plastic strain rate. In rheology, it designates regions where non-Newtonian fluids behave as flowing continua. In geoscience, the term can apply to magmatic or rock systems where temperature and pressure allow ductile flow, such as in lava domes or deep crustal rocks.

Key characteristics include dependence on loading and thermal conditions and delineation from solid-like regions by a yield criterion or flow rule. The boundary between the Fließbereich and non-flow regions may be dynamic, changing with time, strain, and evolving fields (stress, temperature). In modeling, the Fließbereich is usually represented by constitutive equations that specify how stress relates to the rate of deformation within that region.

Synonyms and related terms are Fließzone or flow domain, depending on the author. The concept is central to understanding how materials transition from elastic or rigid behavior to flowing behavior under given conditions. See also: plasticity, creep, rheology, non-Newtonian flow, yield criteria.