Bubble Nucleation model

The Thermoplastics microcellular injection molding simulation process, which is available with the Ultimate license, has been enhanced with the addition of a fitted classical bubble nucleation model. You can now choose to use the existing default Constant nucleation density model, which assumes a constant nucleation density throughout the part, or you can select the new Fitted classical nucleation model.

The Fitted classical nucleation model assumes that nucleation occurs in any region of the polymer and only depends on the average concentration of the physical foaming agent. With this implementation, the effect of shear/ extensional stress on nucleation is ignored. The bubble nucleation starts as soon as J, the nucleation rate, shows a non-zero value. The gas concentration in the resin is calculated based on the mass balance for the gas in the resin and the bubble.

This model is available for selection for all three mesh types;

• Midplane,
• Dual Domain
• 3D

For 3D meshes, bubble nucleation/ growth is calculated when filling begins. For Midplane and Dual Domain the calculation starts when the nozzle is closed.

The following new results are available with the implementation of this bubble nucleation model:

• Bubble number density
• Bubble number density, final (for Midplane and Dual Domain only)