Fatigue Analysis Through Finite Element Models For Paper Suction Rolls

Mario Vega, Mario Razeto, Emilio Dufeu, Alvaro Hillerns


This paper focuses on the application of fatigue life prediction to paper suction rolls. The
procedure was developed to perform failure analysis requested by a local paper manufacturer.
A numerical method must be employed to determine stresses, due to both the complex loading and the
stress concentrators induced by perforations on the shell. The finite element method was used. A twomodel
approach was chosen. A global model of the roll was constructed using shell elements and
taking into account the orthotropic behaviour induced by the perforations. A detailed plane stress
model was used to compute the stress concentrators around perforations. Fatigue analysis was
performed. Multi-axial stress concentration factors were determined from stress results. The high
perforated area on the shell made it necessary to introduce an area reduction factor usually not
accounted for in fatigue analysis. Reliability of the roll was determined taking into account the high
number of notches.
The convergence of the stress solution was investigated, via successive refinement of the mesh.
Automatic refinement tools are not suitable to this problem given the amount of stress concentrators.
Results from analysis indicate that the two mayor factors affecting the predicted life of the roll are the
stress concentrators around the perforations and the loss of reliability due to the amount of these
notches. Hence, the accuracy of stress results from the finite element models is particularly important
in this problem.

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