Areal Density
The mass of a protective panel per unit area, in kg/m² — the number that decides whether a protection level is affordable in weight.
Protection is a weight budget before it is a materials choice. A 6 mm armour steel panel is about 47 kg/m²; an aluminium panel of equal protection is thicker but lighter, which is why light and amphibious hulls move to 5083 or 7039 despite the cost. Comparing materials on thickness alone hides the trade; comparing on areal density at a stated threat level is the only like-for-like.
Related terms
Where this applies
armour-ballistic-materials
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