(T-FORMCAD is no longer available for licensing as of Dec. 31, 2004)

What is T-FORMCAD?

T-FORMCAD is a software package that solves the equations describing the deformation of a polymeric sheet or parison by application of pressure or vacuum. It is used to simulate the process of thermoforming without plug assistance, and blow molding without pre- or simultaneous stretching. The program gives accurate wall thickness predictions during the thermoforming or blow molding processes for fully 3-D geometries. It has been used to simulate the thermoforming of complex refrigerator liners, and several other consumer products.

What is the numerical method?

The finite element method for the membrane approximation is used. Triangular elements on a finite element grid are automatically created on the sheet or parison surface. The finite element method solves the force equilibrium equations for a membrane, and the deformation and thickness are determined during the forming process.

How much knowledge of the finite element method is needed to solve problems?

Absolutely none! The program is menu-driven and easy to use. Grid and mold geometries are straightforward to create even for complex shapes.

What material parameters are needed?

Independent biaxial (preferably) or uniaxial stress-strain data at different temperatures must be available. Material parameters are determined by fitting the Ogden model of rubber elasticity to the stress-strain data. We have a very active research program on the development of a constitutive equation which is capable of describing stress-strain behavior of thermoplastics under thermoforming and blow molding conditions.

How can we evaluate the performance of different polymer grades?

Different resins have different material parameters and therefore T-FORMCAD gives different predictions.

How do the prediction results compare to experimental data and real-life situations?

T-FORMCAD has been successfully used for simulation of thermoforming of various shapes including a door handle of a recreational vehicle (HDPE), food trays, and complex refrigerator liners (ABS). Excellent comparison has been obtained in blow molding of PET soft drink bottles and automotive fuel tanks. The numerical technique is constantly being refined for higher resolution and reliability of predictions.

Can T-FORMCAD read graphic files from CAD packages?

Yes, indirectly. T-FORMCAD is distributed with template files for converting finite element meshes for molds and sheets created within Hypermesh, the 3-D finite element mesh generation package from Altair Engineering, Inc., into a format that T-FORMCAD can read. Hypermesh has built-in translators for many types of graphic files, so existing mold files from CAD packages could be translated to T-FORMCAD format through Hypermesh.

What are the software limitations?

T-FORMCAD cannot be used simulate plug-assisted thermoforming, or blow molding with pre- or simultaneous stretching. As well, only sheets of uniform thickness can be specified, and temperature effects are not incorporated into the material model. Finally, T-FORMCAD does not support webbing of the material sheet.

Click to see Sample Screens

Click to see animation of beverage bottle inflation (offline)

Return to the List of Programs

References

B.L. Koziey, M.O. Ghafur, J. Vlachopoulos and F.A. Mirza, "Computer Simulation of Thermoforming", in Composite Sheet Forming, D. Bhattacharyya (Ed.), Elsevier, Amsterdam, 75-89 (1997).