Why is corrugated board stronger than plain flat board?
The easiest way to think of corrugated board is a series of tubes joined together to form a strip. A cylinder is very strong and can support weight on its edges without crumpling unlike a flat piece of board. You can prove this for yourself by cutting an old cardboard postal tube into a series of shorter tubes. Now glue them together edge to edge along the length of the tube to form a circle. You will find that your cylinder of tubes will support a heavy book like a dictionary all on the edges of board.
