BathAfrica: Add rewritten practical lesson with steps, code and expected results

2026-10-29T21:01:05Z

Add rewritten practical lesson with steps, code and expected results

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__NOTOC__
{{OpenSite scope}}
{{OpenSite lesson
|id=opensite.help.dimensionless-material-expressions
|summary=Assign a Python scalar expression to a dimensionless material property.
|prerequisites=A practice user material and the Python expression runtime. This lesson is separate from a material-standard definition.
|steps==== Create the material ===
Use the same practice-material inputs as the material creation lesson.

=== Choose a dimensionless target ===
Poisson ratio is dimensionless. A bare Python scalar may fill this quantity destination; it cannot stand in for an arbitrary dimensional length or pressure.

=== Store and recalculate ===
The rewritten expression is <code>0.22 + 0.08 * cos(60°)</code>, with degree conversion in Python. Enable consent, then request recalculation.

=== Check the value ===
The arithmetic result is 0.26. Read the property from the material object and compare with that independent expected number.

|result=The object’s Poisson value is 0.26 within 1e-12.
|limitations=Arithmetic correctness is not validation of the chosen constitutive model or a design standard. Keep source, units and material assumptions together.
}}

== Complete example ==
{{Code|lang=python|code=<nowiki>import math
import opensite

doc = opensite.execute("document.new", {})["document"]
created = opensite.material_create_user(doc, {
"name": "Practice steel", "family": "steel", "role": "structural_steel",
"has_elastic": True, "elastic_pa": 210.0e9,
"has_poisson": True, "poisson": 0.28,
"has_mass_density": True, "mass_density": 7850.0,
"has_thermal": True, "thermal_per_k": 1.2e-5,
})
source = "0.22 + 0.08 * math.cos(math.radians(60))"
opensite.execute("document.set_expression", {
"document": doc, "object": created["id"], "property": "poisson",
"expression": source, "language": "python",
})
opensite.execute("document.set_python_expressions_enabled", {
"document": doc, "enabled": True,
})
opensite.recalculate_python_expressions(doc)
actual = doc.get_object(created["id"]).poisson.si_value
assert abs(actual - 0.26) < 1e-12
print("Dimensionless Poisson value:", actual)</nowiki>}}

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BathAfrica: Add rewritten practical lesson with steps, code and expected results