the.com/corrugation
engineering learned that a wrinkle is just a flat surface with a spine.
means a series of parallel ridges and grooves that make a thin material stiff without adding weight or thickness.
from from latin corrugare, to wrinkle, from com- (together) plus rugare (to crease) — the word for a bad complexion became the secret of cardboard boxes and roman aqueducts.
first patent1856, for lining hats, not boxes
cardboard reasontrapped air channels resist bending both ways
iron sheetscorrugated roofing spread across empires by 1830s
road versionwashboard ruts form from repeated tire vibration