3.1. Finite element model
The experimental fan blade specimen was shown in Fig.3. The fan was
composed of hub, wheel and 60 blades. When the fan was driven by
variable frequency motor to rotate, the blades were under the
interactive fatigue load for a long time, which may lead to the blades
fatigue failure under a certain number of cycles. The finite element
model of the fan blade was established to simulate the working condition
of the fan blade, so as to determine the dynamic stress distribution of
the fan blade, the maximum stress in the stress concentration area and
the possible failure position of the blade[35]. In this study, we
used ANSYS software for analysis and a 3D finite element model of fan
blade was established. We used Hypermesh software to mesh the fan blade
model, and on account of the complexity of geometric structure, the
simulation model was established by 427K 8 nodes solid hexahedron
elements. The mesh size was 0.4~5mm, and 1.1 million
hexahedron meshes were divided, as shown in Fig.4. Considering the
influence of friction force and contact force of structural parts of
fan, centrifugal force simulation of all elements in the model was
carried out by using angular velocity. The stress distribution at
critical point of blade components was calculated.