FEA Simulation
CAD MODELS
Multiple simulations of different CAD models of the fluid pump were attempted in Abaqus FEA. The first simulation was done using a CAD that most highly resembled the fully fabricated and assembled pump, composed of the outer rigid cylindrical casing made from Polylactic Acid (PLA) enclosing the soft polymer Ecoflex pneumatic actuator, with rigid PLA end caps sealing off the air pockets as seen in the left figure above. The first simulation failed to deform. A second CAD was created to simplify the model, modeling only a single air pocket of the pneumatic actuator with a rigid backing and rigid end closures (middle figure above). The curved geometry resembled a wedge of a single pocket of the fluid pump. The meshing on the end caps of the single pocket showed some non-uniformity in the unit cells and the FEA runs aborted after each of the multiple attempts to correct the problem. The final CAD model was of a much more simplified air pocket that was constructed to create a pocket with the addition of a rigid backing (right figure above). This part of the pump had a simple rectangular geometry that was elongated to model a single pocket of the pneumatic actuator. The simulation for this simple geometry was successful.
To better model the 10 pockets of the actual pump, the single pocket was multiplied and revolved around a generated axis to create a model that better represented the fluid pump. The FEA simulation resembled the real life behavior of the pneumatic actuator of the fluid pump. In the relaxed or undeformed state, the chamber inside the pump is large and would provide space for fluid to fill. In the contracted or deformed state, the inflated pockets expands into the space of the chamber and the chamber reduces in size. The expansion of the pockets of the pump would displace fluid, pumping fluid out of the chamber. The first figure on this page shows the stress experienced in the inflated pump, with the greatest stress at the area enclosing the chamber.
