Abstract
This report focuses on the modeling air ducts and the mathematical limited pressure. Recently, the air duct made of thinner iron sheet is used for the reason of the global environmental protection and the construction. However, the strength of the air ducts is not clear. Therefore, we constructed the prediction of the limited pressure in the normal air ducts. The normal air duct made of many parts is replaced to the simple structural elements. As the result, the elementary structural mechanics are applied.
