Abstract
When the strong wind blew at an umbrella parallel to the ground from the unexpected direction, the umbrella was lifted by the lift force, and the umbrella was inclined to the opposite direction of the wind by the drag force. The umbrella received a strong wind on the back side (concave), and the umbrella turned inside out, and the ribs were broken in this way. These were found settled as follows. When a hinge turning freely was arranged at the top of axis of umbrella and the angle was maintained with springs, the umbrella inclined to the direction of wind, and the umbrella received downward lift force. The umbrella could always receive the strong wind on the convex surface, and ribs would not be broken. Furthermore, it would reduce the rain person suffered.
