The phrase "steel armature" refers to a framework or structure made of strong steel material. It is used to provide support, stability, or reinforcement to something, such as sculptures, buildings, or electrical appliances. Full definition
Projector and video projection, chromed steel, and dichronic plexi mounted on steel armature. (magazine.art21.org)
Vinyl over steel armature with attached vacuum - formed plastic leaves, cast urethane buds, cast dental acrylic petals, vinyl monofilament stamens and pistils; painted with lacquer and acrylic paint; dusted with volcanic ash from Mount St. Helens, WA, 1980, 72 × 15 in. (tampamuseum.org)
Sanell Aggenbach East Grass on cotton over steel armature Installation view at Jan Marais Nature Reserve (artthrob.co.za)