Structural Matters of Interest

(1-2 minutes to read)

The following provides a simple overview of the behavior of fan blades when under live loads. Blades are subjected to both inertial and aerodynamic forces, which produce a sumtotal of loads on the system. These total loads are the result of steady-state as well as unsteady loads. Structurally, steady state is relatively simple to account for, however, unsteady loads are more of interest; cyclic loads cause high-frequency fatigue to accumulate.

Following are gif files of blade bending and torsion activites, with

1. a standard fan blade moving from no load to normal maximum RPM and thrust and
2. a modified blade moving from no load to the same thrust load, at a lower RPM.

The deflection of the blades and the stresses are shown as follows: