We have finally got around to posting this nice job from last month: a Pressure Vessel FEA and fatigue assessment of a polymer industrial water filter at 10 bar, for use in Europe and the United States. The analysis was conducted using ANSYS Mechanical Workbench 2020 R1.
Mechanika Ltd assessed the original design and identified a number of areas for fatigue life improvement; the changes were quantified and fed back to the client, who implemented the changes. The geometry was then re-assessed to show acceptable fatigue life and robust structural performance.
The threaded interface between the head and body was assessed using non-linear frictional contacts with simulated preload, to determine accurate stresses around the joint – without falsely fixing it with linear bonded contacts and returning singularities with unrealistic restraints. The threaded joint was post processed to quantify the local axial defections around the O-ring seal, to confirm that there would be no breach of containment.
No fixtures were applied to the model, only internal pressure and nozzle loads, which demonstrated model equilibrium.
A traditional fatigue life calculation was undertaken from first principles, using the principle stresses in the areas of high stress and likely fatigue crack initiation.
The Water Filter was subsequently pressure tested and displayed acceptable fatigue life.