Mechanika have recently analysed a plastic pressure vessel for a beverage brewing company in the UK.
The bottle was designed for 3 bar working pressure and 6 bar proof pressure. Mechanika assessed the following items using FEA in ANSYS Mechanical Workbench 2020 R1 and hand calculations:
- Static pressure analysis
- Combined thermal analysis
- Creep Assessment
- Fatigue life prediction
A half symmetry model was created, which expedited the calculation process and also enabled a significantly finer mesh to be applied in regions of high stress – without compromising the calculation speed.
During the analyses process Mechanika identified some product simplifications for design improvement, which reduced the mean stress in the bolted flange and enabled the equipment to meet the desired fatigue life of 1E4 cycles.
The bolted joints were initially assessed from first principals, using hand calculations to determine the joint stiffness and load at which joint separation would occur, which correlated with the FEA to within 5%.