pakkingsgrad

Pakkingsgrad, or packing density, is a measure of how much of a given volume is occupied by solid material as opposed to voids. It is commonly defined as φ = Vs / Vt, where Vs is the volume occupied by the particles and Vt is the total sample volume. The concept is used across disciplines such as granular materials, powders, soils, ceramics, and composites, and influences properties like porosity, permeability, mechanical strength and transport of fluids.

In sphere packings, the packing density depends on the arrangement of the particles. For equal spheres, theoretical values vary by crystal structure: simple cubic packing yields about 0.52, body-centered cubic about 0.64–0.68, and the densest ordered packings (face-centered cubic or hexagonal close packing) about 0.74. Random or loose packings typically achieve lower densities, with random close packing around 0.64. These benchmarks help interpret real materials where particle size distribution, shape, and friction alter the actual density.

In crystallography and materials science, the packing factor (or packing efficiency) describes the fraction of a unit cell volume occupied by atoms. It depends on atomic radii and the crystal structure; many close-packed metals exhibit packing factors near 0.74, while less efficient structures have lower values. The packing factor relates to density and to how tightly atoms can be arranged in a solid.

Measurement and relevance: packing density is estimated through methods such as density measurements, porosity calculations, mercury intrusion porosimetry, X-ray tomography, and imaging analysis. It informs design choices in ceramics, composites, cement, batteries, and filtration, where space utilization and fluid transport are critical.