113 lines
3.9 KiB
Python
113 lines
3.9 KiB
Python
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"""Integration test for the Simply Supported Beam (Quad) example (Ex 6.4)."""
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from __future__ import annotations
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import tempfile
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from pathlib import Path
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import pytest
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pytest.importorskip("openseespy")
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from otko.services import load_project, save_project # noqa: E402
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from otko.services.opensees_runner import OpenSeesRunner # noqa: E402
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pytestmark = pytest.mark.slow
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def test_beam_quad_2d_midspan_deflection(tmp_path) -> None: # type: ignore[no-untyped-def]
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"""10-step LoadControl on a 16×4 plane-stress quad mesh — reference
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midspan deflection ≈ 0.394 in (matches the OpenSees Wiki Ex 6.4 result).
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Validates the new QuadElement emit path for ndm=2, ndf=2 models.
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"""
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from examples.beam_quad_2d import (
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_mid_bottom_node_id,
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_mid_top_node_id,
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build_beam_quad_2d,
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)
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proj = build_beam_quad_2d()
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proj.validate_references()
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path = tmp_path / "beam_quad.osmodel"
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save_project(proj, path)
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reloaded = load_project(path)
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reloaded.validate_references()
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result = OpenSeesRunner(reloaded).run(reloaded.analyses[0])
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l1 = _mid_bottom_node_id()
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l2 = _mid_top_node_id()
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uy_bottom = result.node_disp[l1][-1, 1]
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uy_top = result.node_disp[l2][-1, 1]
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# Reference (pure openseespy with the same mesh): Uy ≈ -0.3943 in at
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# both midspan nodes after 10 steps of LoadControl (load factor = 10).
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assert uy_bottom == pytest.approx(-0.3943, abs=1e-3)
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assert uy_top == pytest.approx(-0.3943, abs=1e-3)
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# Top and bottom midspan deflections differ only by Poisson-contraction
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# through the beam depth — a few microinches.
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assert abs(uy_top - uy_bottom) < 1e-4
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# By symmetry, left and right support reactions must balance the two
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# 10-kip midspan loads (total -20 kip vertical).
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assert reloaded.nodes[0].id == 1 # left pin
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reaction_sum_fy = sum(
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result.node_reaction[nid][-1, 1]
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for nid in (1, 17) # node 17 = (L, 0) = roller
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)
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assert reaction_sum_fy == pytest.approx(20.0, abs=1e-6)
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def test_beam_quad_2d_free_vibration_chain(tmp_path) -> None: # type: ignore[no-untyped-def]
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"""TransientCase with preload + remove_patterns + mode-1 Rayleigh.
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Confirms the chained-analysis support: after the Static preload,
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dropping pattern 1 leaves the beam oscillating freely about Uy=0
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with 2% stiffness-proportional damping, and the amplitude decays
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monotonically in the envelope sense.
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"""
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from examples.beam_quad_2d import (
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_mid_bottom_node_id,
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build_beam_quad_2d,
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)
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proj = build_beam_quad_2d()
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proj.validate_references()
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path = tmp_path / "beam_quad.osmodel"
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save_project(proj, path)
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reloaded = load_project(path)
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reloaded.validate_references()
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results_dir = Path(tempfile.mkdtemp(prefix="beamvib_"))
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r = OpenSeesRunner(reloaded).run(reloaded.analyses[1], results_dir=results_dir)
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import h5py
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with h5py.File(r.h5_path) as f:
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t = f["time"][:]
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u = f[f"nodes/{_mid_bottom_node_id()}/disp"][:, 1]
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# Transient starts at t=0 (loadConst reset) and runs 1500 × 0.5 = 750 s.
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assert t[0] == pytest.approx(0.5, abs=0.01)
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assert t[-1] == pytest.approx(750.0, abs=0.5)
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# Initial displacement inherits the ~0.394-in static sag. The first
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# sample is one transient step in (dt = 0.5 s), so we're a hair away
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# from the peak but still well inside the first half-cycle.
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assert u[0] == pytest.approx(-0.394, abs=0.02)
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# Oscillatory motion: amplitude swings to both signs.
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assert u.min() < -0.1
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assert u.max() > +0.05
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# 2 % stiffness-proportional damping over 750 s drives the amplitude
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# to well below the initial sag — envelope (peak-to-peak across the
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# final 100 samples) should be a small fraction of the initial |u|.
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final_envelope = abs(u[-100:]).max()
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assert final_envelope < 0.05, (
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f"Final-envelope amplitude {final_envelope:.4f} in — "
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"damping did not attenuate the free-vibration response."
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)
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