{
  "schema": "copv_c02_structural_elastic_v1",
  "case_id": "C02_detailed_baseline_1MPa",
  "units": {
    "length": "mm",
    "force": "N",
    "stress": "MPa",
    "energy": "N mm"
  },
  "scope": "Small-displacement static linear-elastic code/research baseline; not a rated pressure, strength, seal, burst or manufactured-vessel qualification.",
  "geometry": {
    "source": "Accepted C01 detailed baseline: metal liner, adhesive, four ply groups, two polar collars, two titanium bosses and two steel inserts.",
    "structural_part_count": 12,
    "display_only_part_count": 6,
    "display_only": "Four elastomer O-rings and two PEEK rings; compression, seal contact and leakage are not modeled.",
    "analysis_repair": "Fit sampled polar-collar inner boundaries to the exact outer-ply CAD surface; retain outer envelopes and boss pockets, record volume changes and source hashes."
  },
  "materials": {
    "aluminum": {
      "grade": "Al 6061-T6",
      "model": "isotropic_linear",
      "E_MPa": 69000.0,
      "nu": 0.33,
      "source": "configs/copv_material_candidates.json -> elastic_control_candidate.liner; NASA 20180003005 Table 4"
    },
    "titanium": {
      "grade": "Ti-6Al-4V",
      "model": "isotropic_linear",
      "E_MPa": 115100.0,
      "nu": 0.28,
      "source": "R02 material-reference.json; NASA/TM-2016-218864 Table II; linear elastic constants only, no plastic curve imported; nu=0.28 is the retained R02 analysis assumption"
    },
    "steel": {
      "grade": "316L",
      "model": "isotropic_linear",
      "E_MPa": 200000.0,
      "nu": 0.3,
      "source": "Alfa Laval EN1.4404/AISI316L physical-properties table gives E=200GPa; nu=0.30 is an explicit isotropic analysis assumption",
      "source_url": "https://www.alfalaval.no/produkter/vaskebehandling/en-1-4404-aisi-316l/"
    },
    "adhesive": {
      "grade": "generic epoxy bondline numerical idealization",
      "model": "isotropic_linear",
      "E_MPa": 3000.0,
      "nu": 0.35,
      "source": "Explicit baseline modeling assumptions, not measured/qualified adhesive properties or an identification with the lamina's 3501-6 matrix"
    },
    "carbon": {
      "grade": "AS4/3501-6 numerical lamina benchmark",
      "model": "orthotropic_linear_3D",
      "E1": 114452.9710665888,
      "E2": 10342.135939752,
      "E3": 10342.135939752,
      "G12": 5998.43884505616,
      "G13": 5998.43884505616,
      "G23": 3792.1165112424,
      "nu12": 0.33,
      "nu13": 0.33,
      "nu23": 0.47,
      "source": "configs/copv_material_candidates.json -> elastic_control_candidate.overwrap; NASA-TM-109108 Table 1, upstream citation not independently retrieved"
    }
  },
  "material_axes": {
    "engineering_strain_voigt": [
      "11",
      "22",
      "33",
      "23",
      "13",
      "12"
    ],
    "engineering_shear": true,
    "definition": "Q columns are [fiber, transverse, normal] in global xyz. m=-unit increasing-z meridian tangent; c=+e_theta; n=m cross c; fiber=cos(alpha)m+sin(alpha)c, transverse=-sin(alpha)m+cos(alpha)c.",
    "ply_angles_degrees_inner_to_outer": [
      55.0,
      -55.0,
      -55.0,
      55.0
    ],
    "polar_collar_angles_degrees": {
      "top": 25.0,
      "bottom": -25.0
    },
    "evaluation": "Rotate full 3D strain/stress at each volume GP; retain transverse shear, curvature and twist. Nominal direction field is a research design choice, not a validated manufacturing winding path."
  },
  "connections": "Perfectly bonded shared structural interfaces; nominal gaps remain unloaded unless explicitly recorded as tied contacts. No friction, opening, cohesive damage or seal crush.",
  "load": {
    "peak_pressure_MPa": 1.0,
    "pressure_traction": "-p*n_solid on the true inner wetted wall and internal port shoulders; exterior pressure zero.",
    "upper_bore_radius_mm": 10.2,
    "lower_bore_radius_mm": 8.25,
    "equivalent_caps": "Each port receives its own p*pi*bore_radius^2 outward axial resultant once, distributed over its actual annular end face; no end-cap solid is invented.",
    "path_pressure_MPa": [
      0.1,
      0.2,
      0.3,
      0.4,
      0.5,
      0.6,
      0.7,
      0.8,
      0.9,
      1.0,
      0.9,
      0.8,
      0.7,
      0.6,
      0.5,
      0.4,
      0.3,
      0.2,
      0.1,
      0.0
    ]
  },
  "gauge": "Free-vessel 3-2-1 nodal gauge at three separated lower-port end points; prove rank six for rigid-motion modes. This removes rigid translation/rotation, not a physical mounting clamp.",
  "discretization": {
    "geometry": "straight-sided Gmsh TET10 with midside coordinates at exact chord midpoints; curved attempt rejected for negative Jacobians",
    "displacement": "P1 vector on the full detailed structural partition; TET10 midside display values are exact affine interpolation, not independent P2 unknowns",
    "volume_quadrature_degree": 4,
    "boundary_quadrature_degree": 4,
    "stress_output": "Original element and GP; no averaging across materials or ply interfaces",
    "limitation": "Detailed P1 code/research baseline. Geometry, mesh and P1/P2 convergence belong to C03; independent P2 verification specimens are not a full detailed P2 solve.",
    "accepted_mesh_directory": "mesh_h6_netgen",
    "mesh_optimizer": "Netgen on linear tetrahedra, then straight-sided TET10 coordinates"
  },
  "backend": {
    "assembly": "CPU FFCx/DOLFINx",
    "linear_algebra": "PETSc CUDA AIJCUSPARSE / CUDA vectors; selected preconditioner recorded in summary and KSP view. Default full-P1 CUDA FGMRES/GAMG with small CPU SVD coarsest solve; optional explicit CPU-HYPRE P1 coarse path is not a silent fallback.",
    "silent_CPU_fallback": false,
    "coarse_backend_explicit": true
  },
  "verification": {
    "orthotropic_specimen": "Independent skfem versus FEniCSx 3-component axisymmetric Quad9, same geometry/BC/load/GP fields, plus CPU/GPU algebra equality",
    "three_dimensional_patch": "Rotated 3D orthotropic straight-sided P2 element checked against analytical affine-strain energy and nodal equilibrium, with CalculiX where available",
    "full_model": "Positive Jacobians and connected load path; force/moment balance, true residual, external work versus twice strain energy, cap resultants, all saved load/unload states",
    "mesh_convergence": "C03; C02 does not claim local peak-stress convergence"
  }
}