Volumenanteil

Volumenanteil, in German often translated as volume fraction, is the fraction of a system’s total volume occupied by a particular phase or component. It is defined as phi_i equals V_i divided by V_total, is dimensionless, and is commonly expressed as a percentage.

In materials science and related fields, Volumenanteil is used to describe multiphase materials such as fibre-reinforced composites, porous ceramics, foams, emulsions, and gas–liquid mixtures. The volume fraction indicates how much space a phase occupies and strongly influences properties such as stiffness, strength, thermal and electrical conductivity, and transport behavior. For example, increasing the fiber volume fraction in a polymer composite typically increases stiffness but can reduce strain to failure; in porous media, porosity corresponds to the volume fraction of voids.

Relation to mass fraction: the mass fraction w_i of a component i relates to its volume fraction by w_i = phi_i times rho_i divided by rho_mix, where rho_i is the component density and rho_mix is the overall mixture density equal to the sum over all phases of phi_j rho_j. Equivalently, phi_i can be obtained from w_i if the densities are known. This shows how density contrasts affect conversions between volume and mass fractions.

Measurement and estimation: Volumenanteil can be determined directly by imaging techniques and image analysis (optical or electronic microscopy, X-ray computed tomography). Indirect methods include gravimetric determinations based on Archimedes’ principle in liquids or porosimetry to measure void fractions. In engineered materials, volume fractions can also be inferred from manufacturing data and material models.

Related concepts include porosity, saturation, and phase geometry, all of which describe how space is partitioned among the phases in a system.