feat: initial otko import

examples/cantilever.py

@@ -0,0 +1,121 @@
+"""Cantilever beam example — ideal for showing force diagrams.
+
+A 5 m horizontal cantilever fixed at the left end, with a point load
+at the tip and a distributed-equivalent set of nodal loads along the
+span. Pure bending response makes for instantly recognisable N/V/M
+diagrams.
+
+Run from the repository root:
+
+    python examples/cantilever.py
+
+Produces ``examples/cantilever.osmodel``.
+Open in the GUI, run "Tip-Load" Static case, then:
+
+  Display → Show Force Diagram → V2 (shear)   → constant within each segment
+  Display → Show Force Diagram → M3 (moment)  → linear, max at the fixed end
+  Display → Show Deformed Shape               → classic cantilever curve
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from otko.core import (
+    ElasticBeamColumn,
+    ElasticSection,
+    LinearTimeSeries,
+    ModalCase,
+    NodalLoad,
+    Node,
+    PlainLoadPattern,
+    Project,
+    ProjectMeta,
+    StaticCase,
+    UniformElementLoad,
+    UnitSystem,
+)
+from otko.services import load_project, save_project
+
+
+def build_cantilever() -> Project:
+    """5 m cantilever discretised into 5 elements (1 m each)."""
+    n_segments = 5
+    seg_len = 1.0
+    nodes = []
+    for i in range(n_segments + 1):
+        x = i * seg_len
+        restraint = (True,) * 6 if i == 0 else (False,) * 6
+        # Lump some mass at every free node so modal works too.
+        mass = (1000.0, 1000.0, 1000.0, 0.0, 0.0, 0.0) if i > 0 else (0.0,) * 6
+        nodes.append(Node(id=i + 1, name=f"N{i+1}",
+                          coords=(x, 0.0, 0.0), restraint=restraint, mass=mass))
+
+    elements = [
+        ElasticBeamColumn(id=i + 1, name=f"E{i+1}",
+                          nodes=(i + 1, i + 2), section_id=1)
+        for i in range(n_segments)
+    ]
+
+    return Project(
+        meta=ProjectMeta(name="Cantilever", author="Ozan", units=UnitSystem.SI_M_N),
+        ndm=3, ndf=6,
+        nodes=nodes,
+        sections=[
+            ElasticSection(
+                id=1, name="W12x40",
+                E=200e9, A=0.0076,
+                Iz=2.0e-4, Iy=4.5e-5,
+                G=80e9, J=8.5e-7,
+            ),
+        ],
+        elements=elements,
+        time_series=[LinearTimeSeries(id=1, name="Ramp")],
+        load_patterns=[
+            # Tip horizontal load (y) of 10 kN — this produces shear V2
+            # and moment M3 about the strong axis, the conventional 2D
+            # "in-plane bending" components.
+            PlainLoadPattern(
+                id=1, name="TipLoad",
+                time_series_id=1,
+                nodal_loads=[
+                    NodalLoad(node_id=n_segments + 1,
+                              forces=(0.0, -10_000.0, 0.0, 0, 0, 0)),
+                ],
+            ),
+            # Uniform distributed load wy = -2 kN/m along every element.
+            # Produces parabolic moment diagram, max at fixed end
+            # (M_max = q·L²/2 = 2·5²/2 = 25 kN·m).
+            PlainLoadPattern(
+                id=2, name="UniformLoad",
+                time_series_id=1,
+                element_loads=[
+                    UniformElementLoad(element_id=i + 1, wy=-2_000.0)
+                    for i in range(n_segments)
+                ],
+            ),
+        ],
+        analyses=[
+            StaticCase(id=1, name="Tip-Load", pattern_ids=[1]),
+            StaticCase(id=2, name="Uniform-Load", pattern_ids=[2]),
+            ModalCase(id=3, name="Modal-3", n_modes=3),
+        ],
+    )
+
+
+def main() -> None:
+    project = build_cantilever()
+    project.validate_references()
+    print(f"Built '{project.meta.name}' — {len(project.nodes)} nodes, "
+          f"{len(project.elements)} elements, {len(project.analyses)} cases.")
+    out_path = Path(__file__).with_suffix(".osmodel")
+    save_project(project, out_path)
+    print(f"Saved -> {out_path}")
+    restored = load_project(out_path)
+    restored.validate_references()
+    assert restored.model_dump(by_alias=True) == project.model_dump(by_alias=True)
+    print("Round-trip OK.")
+
+
+if __name__ == "__main__":
+    main()