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Materials & Rheology

Constitutive models

PyExtrusion 0.19.0 exposes two separate hot-working constitutive datasets:

  • AA6063;
  • AA6060.

Use the short public names in normal workflows:

from pyextrusion.engineering import AA6060, AA6063

These names are aliases of the existing model objects, not copies or new datasets. The source-specific names remain available for backward compatibility; see the provenance mapping. No material registry or additional alloy dataset is introduced.

Both are HotWorkingConstitutiveModel instances. They contain the parameters used by the hyperbolic-sine flow-stress relationship together with source references and explicit notes. The two alloys are not interchangeable, and the constants do not claim to represent every chemistry, homogenisation state, supplier or production lot.

Equivalent geometry

equivalent_extrudate_diameter_mm() derives a circular diameter that preserves the total simultaneously extruded area for a supplied container diameter and extrusion ratio. It is an equivalent-axisymmetric geometry, not a claim that the real profile is circular.

Modified Feltham mean strain rate

modified_feltham_mean_strain_rate_s_1() evaluates the scalar mean strain-rate relationship used by the Sheppard model. If the deformation semi-angle is not provided, PyExtrusion evaluates the documented empirical relationship from the extrusion ratio.

The result is a mean value for the deformation zone. It is not a local strain-rate field.

Zener-Hollomon and flow stress

The public rheology chain is:

  1. calculate mean strain rate;
  2. calculate log_zener_hollomon_parameter() or zener_hollomon_parameter_s_1();
  3. calculate steady_state_flow_stress_mpa() from Z, or use flow_stress_mpa() for the combined calculation.

The logarithmic API is useful when Z would be inconveniently large. All temperatures passed to the public API are in degrees Celsius; conversion to absolute temperature is performed internally.

See the Engineering API for an executable example and the technical references for source attribution.