Material Model for 3D Printed Nylon Filament

Nylon is a commonly used material for 3D printing. The following figure shows experimental data obtained from compressing a single filament in the transverse  direction. The filament was coiled up and compressed between two parallel compression platens.

The experimental data was only obtained in the transverse compressive direction at one strain rate (-0.0012/s) at room temperature.  Since the data is only available at one strain rate it difficult to calibrate a viscoplastic material model. Here I selected to calibrate 3 material models:

  • Abaqus elastic-plastic (with isotropic hardening plasticity)
  • ANSYS elastic-MISO plastic
  • PolyUMod Three Network (TN) Model.

In order to calibrate the TN model I assumed that the strain-rate dependence of the material is similar to other Nylons, and selected the parameter m=10 (for both flow networks). The following figures show the calibration results.

Note that for the TN model I also included the predictions (see the green curve) at a 100 times faster cyclic strain rate. The predictions at that strain rate, of course, are only approximately correct. But the TN model predictions are likely more accurate than the strain-rate independent elastic-plastic models.

The following link contains all files that I used in this case study.

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