forked from 1b-agent/fieldcraft-upstream
jyvikoandClaude Opus 5.5
a30d0b5c5b
Segment-to-segment penalty contact between element faces: each secondary face and each main face facing it are projected onto the secondary face's plane, split into triangles, clipped (Sutherland–Hodgman) and integrated with a three-point rule per sub-triangle (Puso–Laursen segmentation, the penalty at the integration points as Fischer–Wriggers), so a uniform pressure gives the consistent nodal forces on both meshes and the contact patch test passes on non-matching meshes. Every contact runs both ways at half the penalty: pairs with each surface as the secondary, general and self contact face against face. A bucket grid of face boxes every increment, faces integrated in parallel and their forces added in face order: the same numbers on any thread count. The penalty per area ε = s γ min(m/A)/Δt² comes from the lumped masses, each node's directional area and the stable increment, bounded by Gershgorin's row sums so contact never shortens the increment. Coulomb friction with exponential decay by a regularised return map at the secondary nodes; rigid walls take Coulomb impulses. Contact work and friction dissipation join the energy balance; each contact reports its peak force, first and last contact, deepest penetration, friction and the nodes adjusted at the start (initial penetrations adjusted strain-free or refused with the node, face and depth); a cap on contact faces. Verified (crates/explicit/tests/contact.rs, tests/oracle/explicit-*): colliding bars (2L/c +1.2%, ρcAv₀/2, KE kept to 0.005%, contact energy back to 8e-5 of it), blocks sliding to a stop on a rigid wall and on a plate under constant and decaying friction (0.005–0.2%), the patch test (σ_zz uniform to 0.06%), two spheres colliding against Hertz (peak +2.3%, duration −0.4%; the oracle case waits for a graded sphere mesher), a free body untouched by general contact, determinism across threads. Oracle measures gain `over` (ratios). Existing fixtures do not move. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm
15 lines
1.8 KiB
JSON
15 lines
1.8 KiB
JSON
[
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{"command": "mesh.block", "params": {"body": "BarA", "kind": "hex8", "corners": [[0, 0, 0], [10.0, 0, 0], [10.0, 0.1, 0], [0, 0.1, 0], [0, 0, 0.1], [10.0, 0, 0.1], [10.0, 0.1, 0.1], [0, 0.1, 0.1]], "divisions": [200, 1, 1], "faces": {"4": "end"}}},
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{"command": "mesh.block", "params": {"body": "BarB", "kind": "hex8", "corners": [[10.0, 0, 0], [20.0, 0, 0], [20.0, 0.1, 0], [10.0, 0.1, 0], [10.0, 0, 0.1], [20.0, 0, 0.1], [20.0, 0.1, 0.1], [10.0, 0.1, 0.1]], "divisions": [200, 1, 1], "faces": {"6": "start"}, "merge": 0}},
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{"command": "model.set.create", "params": {"name": "A", "geometry": [{"body": "BarA"}]}},
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{"command": "model.set.create", "params": {"name": "B", "geometry": [{"body": "BarB"}]}},
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{"command": "model.set.create", "params": {"name": "a_end", "geometry": [{"body": "BarA", "face": "end"}]}},
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{"command": "model.set.create", "params": {"name": "b_start", "geometry": [{"body": "BarB", "face": "start"}]}},
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{"command": "model.material.create", "params": {"name": "Mat", "elastic": {"type": "isotropic", "young": 10000.0, "poisson": 0.0}, "density": 1.0}},
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{"command": "model.section.create", "params": {"name": "A", "set": "A", "material": "Mat", "kind": {"type": "solid"}, "formulation": {"integration": "reduced"}}},
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{"command": "model.section.create", "params": {"name": "B", "set": "B", "material": "Mat", "kind": {"type": "solid"}, "formulation": {"integration": "reduced"}}},
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{"command": "interaction.contact.pair", "params": {"name": "impact", "main": "b_start", "secondary": "a_end"}},
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{"command": "model.step.create", "params": {"name": "Impact", "procedure": {"type": "explicit_dynamic", "end_time": 0.3, "initial_velocities": [{"set": "A", "velocity": [0.1, 0, 0]}], "bulk_viscosity": {"linear": 0.0, "quadratic": 1.5}}, "boundary_conditions": [], "loads": []}},
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{"command": "solve.explicit", "params": {"step": "Impact"}, "id": "solve"}
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]
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