verification: implicit contact patch test and Hertz line contact

Two oracle cases: the contact patch test on non-matching meshes in small and finite sliding,
and Hertz's cylinder on a flat under force control (peak pressure, pressure distribution,
subsurface stress). docs/fem.md describes the formulation, the literature survey its papers;
ROADMAP M7 and parity are updated.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo
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jyvikoandClaude Opus 5.5 authored and Irakli Kourtis committed 2026-10-14 14:58:32 -04:00
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# Contact patch test (implicit mortar contact, non-matching meshes)
Two unit cubes stacked along z, meshed independently: 3 × 3 × 2 hex8 below (graded in x and y),
2 × 2 × 2 above, so the nodes of the interface at z = 1 do not match. A frictionless contact pair
joins the lower block's top (main) and the upper block's bottom (secondary). The faces x = 0 and
y = 0 of both blocks are symmetry planes, the base z = 0 is held in z, and the top z = 2 is pushed
down by 0.02 (E = 1000, ν = 0.3) in two nonlinear static steps: `Small` without nonlinear
geometry (small sliding, mortar integrals in the reference configuration) and `Finite` with it
(finite sliding, searched and integrated on the deformed faces). The exact state is uniaxial
stress, uniform in both blocks, with a uniform contact pressure equal to it.
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{
"title": "Contact patch test: two blocks with non-matching meshes in uniaxial compression (implicit mortar contact)",
"kind": "theory",
"source": "The contact patch test: a contact discretisation must transmit a uniform pressure across a non-matching interface exactly; Taylor & Papadopoulos, On a patch test for contact problems in two dimensions, Nonlinear Computational Mechanics, Springer 1991, 690–702; Crisfield, Re-visiting the contact patch test, IJNME 48:435–449, 2000; passed by mortar methods: Puso & Laursen, CMAME 193:601–629, 2004. Uniaxial stress between frictionless symmetry planes is uniform in both blocks",
"quantities": [
{
"id": "small_lower_corner",
"quantity": "Small: σ_zz of the lower block's corner element under the interface (element 10) over that of the upper block's corner element over it (element 19)",
"measure": {
"command": "solve.probe",
"params": {
"step": "Small",
"elements": [
10
]
},
"pointer": "/elements/0/stress/0/2",
"over": {
"command": "solve.probe",
"params": {
"step": "Small",
"elements": [
19
]
},
"pointer": "/elements/0/stress/0/2"
}
},
"value": 1.0,
"tolerance": {
"relative": 1e-06
},
"reason": "small sliding is linear and its mortar integrals exact on these rectangular faces: a uniform stress is the discrete solution up to the convergence tolerance (10⁻¹⁰)"
},
{
"id": "small_lower_centre",
"quantity": "Small: σ_zz of the lower block's centre element under the interface (element 14) over that of element 19",
"measure": {
"command": "solve.probe",
"params": {
"step": "Small",
"elements": [
14
]
},
"pointer": "/elements/0/stress/0/2",
"over": {
"command": "solve.probe",
"params": {
"step": "Small",
"elements": [
19
]
},
"pointer": "/elements/0/stress/0/2"
}
},
"value": 1.0,
"tolerance": {
"relative": 1e-06
},
"reason": "as for the corner element"
},
{
"id": "small_lower_base",
"quantity": "Small: σ_zz of the lower block's bottom corner element (element 1) over that of element 19",
"measure": {
"command": "solve.probe",
"params": {
"step": "Small",
"elements": [
1
]
},
"pointer": "/elements/0/stress/0/2",
"over": {
"command": "solve.probe",
"params": {
"step": "Small",
"elements": [
19
]
},
"pointer": "/elements/0/stress/0/2"
}
},
"value": 1.0,
"tolerance": {
"relative": 1e-06
},
"reason": "as for the corner element"
},
{
"id": "small_upper_top",
"quantity": "Small: σ_zz of the upper block's top far corner element (element 26) over that of element 19",
"measure": {
"command": "solve.probe",
"params": {
"step": "Small",
"elements": [
26
]
},
"pointer": "/elements/0/stress/0/2",
"over": {
"command": "solve.probe",
"params": {
"step": "Small",
"elements": [
19
]
},
"pointer": "/elements/0/stress/0/2"
}
},
"value": 1.0,
"tolerance": {
"relative": 1e-06
},
"reason": "as for the corner element"
},
{
"id": "small_lateral",
"quantity": "Small: σ_xx of element 14 over its σ_zz (uniaxial stress: 0)",
"measure": {
"command": "solve.probe",
"params": {
"step": "Small",
"elements": [
14
]
},
"pointer": "/elements/0/stress/0/0",
"over": {
"command": "solve.probe",
"params": {
"step": "Small",
"elements": [
14
]
},
"pointer": "/elements/0/stress/0/2"
}
},
"value": 0.0,
"tolerance": {
"absolute": 1e-06
},
"reason": "frictionless symmetry planes and a frictionless interface leave the blocks free to expand sideways; the non-matching interface must not hold them"
},
{
"id": "small_pressure",
"quantity": "Small: the contact pressure at the secondary node (0.5, 0.5, 1) over −σ_zz of element 19",
"measure": {
"command": "solve.probe",
"params": {
"step": "Small",
"at": [
[
0.5,
0.5,
1.0
]
]
},
"pointer": "/nodes/0/contact/0/pressure",
"over": {
"command": "solve.probe",
"params": {
"step": "Small",
"elements": [
19
]
},
"pointer": "/elements/0/stress/0/2",
"scale": -1.0
}
},
"value": 1.0,
"tolerance": {
"relative": 1e-06
},
"reason": "the mortar multipliers are the nodal values of the contact pressure, uniform and equal to the stress across the interface"
},
{
"id": "small_force",
"quantity": "Small: the integrated contact pressure over the reaction at the pushed top",
"measure": {
"from": "small",
"pointer": "/contacts/0/normal_force",
"over": {
"command": "results.reactions",
"params": {
"step": "Small",
"sets": [
"top"
]
},
"pointer": "/sets/0/force/2",
"scale": -1.0
}
},
"value": 1.0,
"tolerance": {
"relative": 1e-06
},
"reason": "the pressure carries the whole load across the interface"
},
{
"id": "finite_lower_corner",
"quantity": "Finite: σ_zz of the lower block's corner element under the interface (element 10) over that of the upper block's corner element over it (element 19)",
"measure": {
"command": "solve.probe",
"params": {
"step": "Finite",
"elements": [
10
]
},
"pointer": "/elements/0/stress/0/2",
"over": {
"command": "solve.probe",
"params": {
"step": "Finite",
"elements": [
19
]
},
"pointer": "/elements/0/stress/0/2"
}
},
"value": 1.0,
"tolerance": {
"relative": 0.0002
},
"reason": "finite sliding is exact up to the geometric terms of the gaps the augmentation leaves (10⁻⁵ of the element thickness) and the default convergence tolerances"
},
{
"id": "finite_lower_centre",
"quantity": "Finite: σ_zz of the lower block's centre element under the interface (element 14) over that of element 19",
"measure": {
"command": "solve.probe",
"params": {
"step": "Finite",
"elements": [
14
]
},
"pointer": "/elements/0/stress/0/2",
"over": {
"command": "solve.probe",
"params": {
"step": "Finite",
"elements": [
19
]
},
"pointer": "/elements/0/stress/0/2"
}
},
"value": 1.0,
"tolerance": {
"relative": 0.0002
},
"reason": "as for the corner element"
},
{
"id": "finite_lower_base",
"quantity": "Finite: σ_zz of the lower block's bottom corner element (element 1) over that of element 19",
"measure": {
"command": "solve.probe",
"params": {
"step": "Finite",
"elements": [
1
]
},
"pointer": "/elements/0/stress/0/2",
"over": {
"command": "solve.probe",
"params": {
"step": "Finite",
"elements": [
19
]
},
"pointer": "/elements/0/stress/0/2"
}
},
"value": 1.0,
"tolerance": {
"relative": 0.0002
},
"reason": "as for the corner element"
},
{
"id": "finite_upper_top",
"quantity": "Finite: σ_zz of the upper block's top far corner element (element 26) over that of element 19",
"measure": {
"command": "solve.probe",
"params": {
"step": "Finite",
"elements": [
26
]
},
"pointer": "/elements/0/stress/0/2",
"over": {
"command": "solve.probe",
"params": {
"step": "Finite",
"elements": [
19
]
},
"pointer": "/elements/0/stress/0/2"
}
},
"value": 1.0,
"tolerance": {
"relative": 0.0002
},
"reason": "as for the corner element"
},
{
"id": "finite_lateral",
"quantity": "Finite: σ_xx of element 14 over its σ_zz (uniaxial stress: 0)",
"measure": {
"command": "solve.probe",
"params": {
"step": "Finite",
"elements": [
14
]
},
"pointer": "/elements/0/stress/0/0",
"over": {
"command": "solve.probe",
"params": {
"step": "Finite",
"elements": [
14
]
},
"pointer": "/elements/0/stress/0/2"
}
},
"value": 0.0,
"tolerance": {
"absolute": 0.0002
},
"reason": "frictionless symmetry planes and a frictionless interface leave the blocks free to expand sideways; the non-matching interface must not hold them"
},
{
"id": "finite_pressure",
"quantity": "Finite: the contact pressure at the secondary node (0.5, 0.5, 1) over −σ_zz of element 19",
"measure": {
"command": "solve.probe",
"params": {
"step": "Finite",
"at": [
[
0.5,
0.5,
1.0
]
]
},
"pointer": "/nodes/0/contact/0/pressure",
"over": {
"command": "solve.probe",
"params": {
"step": "Finite",
"elements": [
19
]
},
"pointer": "/elements/0/stress/0/2",
"scale": -1.0
}
},
"value": 1.0,
"tolerance": {
"relative": 0.0002
},
"reason": "the mortar multipliers are the nodal values of the contact pressure, uniform and equal to the stress across the interface"
},
{
"id": "finite_force",
"quantity": "Finite: the integrated contact pressure over the reaction at the pushed top",
"measure": {
"from": "finite",
"pointer": "/contacts/0/normal_force",
"over": {
"command": "results.reactions",
"params": {
"step": "Finite",
"sets": [
"top"
]
},
"pointer": "/sets/0/force/2",
"scale": -1.0
}
},
"value": 1.0,
"tolerance": {
"relative": 0.0002
},
"reason": "the pressure carries the whole load across the interface"
},
{
"id": "small_stress",
"quantity": "Small: σ_zz of element 19 (uniaxial stress E ε = −10 for the 1% squeeze)",
"measure": {
"command": "solve.probe",
"params": {
"step": "Small",
"elements": [
19
]
},
"pointer": "/elements/0/stress/0/2"
},
"value": -10.0,
"tolerance": {
"relative": 0.0001
},
"reason": "the squeeze less the penetration the augmented Lagrangian leaves (up to 10⁻⁵ of the element thickness, a few 10⁻⁵ of the squeeze)"
}
]
}
@@ -0,0 +1,65 @@
{
"note": "FieldCraft's accepted results for this case, written by `cargo xtask oracle --bless`. A result outside its band fails CI.",
"values": {
"finite_force": {
"band": 1e-9,
"value": 0.9999999999974551
},
"finite_lateral": {
"band": 0.0002,
"value": 1.223600676667172e-6
},
"finite_lower_base": {
"band": 1e-9,
"value": 0.9999905821256437
},
"finite_lower_centre": {
"band": 1e-9,
"value": 0.999987114528879
},
"finite_lower_corner": {
"band": 1.000001514518151e-9,
"value": 1.000001514518151
},
"finite_pressure": {
"band": 1e-9,
"value": 0.9999828003418422
},
"finite_upper_top": {
"band": 1e-9,
"value": 0.9999912761681571
},
"small_force": {
"band": 1.0000000000000607e-9,
"value": 1.0000000000000606
},
"small_lateral": {
"band": 1e-6,
"value": 7.880554574306202e-15
},
"small_lower_base": {
"band": 1e-9,
"value": 0.999999999999944
},
"small_lower_centre": {
"band": 1e-9,
"value": 0.9999999999999398
},
"small_lower_corner": {
"band": 1e-9,
"value": 0.9999999999999855
},
"small_pressure": {
"band": 1e-9,
"value": 0.9999999999999953
},
"small_stress": {
"band": 1e-8,
"value": -9.99957382191768
},
"small_upper_top": {
"band": 1e-9,
"value": 0.9999999999999263
}
}
}
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[
{"command": "mesh.block", "params": {"body": "Lower", "kind": "hex8", "corners": [[0, 0, 0], [1, 0, 0], [1, 1, 0], [0, 1, 0], [0, 0, 1], [1, 0, 1], [1, 1, 1], [0, 1, 1]], "divisions": [3, 3, 2], "faces": {"1": "bottom", "2": "top", "3": "y0", "6": "x0"}, "bias": [2.0, 0.6, 1.0]}},
{"command": "mesh.block", "params": {"body": "Upper", "kind": "hex8", "corners": [[0, 0, 1], [1, 0, 1], [1, 1, 1], [0, 1, 1], [0, 0, 2], [1, 0, 2], [1, 1, 2], [0, 1, 2]], "divisions": [2, 2, 2], "faces": {"1": "bottom", "2": "top", "3": "y0", "6": "x0"}, "merge": 0}},
{"command": "model.set.create", "params": {"name": "lower", "geometry": [{"body": "Lower"}]}},
{"command": "model.set.create", "params": {"name": "upper", "geometry": [{"body": "Upper"}]}},
{"command": "model.set.create", "params": {"name": "lower_top", "geometry": [{"body": "Lower", "face": "top"}]}},
{"command": "model.set.create", "params": {"name": "upper_bottom", "geometry": [{"body": "Upper", "face": "bottom"}]}},
{"command": "model.set.create", "params": {"name": "x0", "geometry": [{"body": "Lower", "face": "x0"}, {"body": "Upper", "face": "x0"}]}},
{"command": "model.set.create", "params": {"name": "y0", "geometry": [{"body": "Lower", "face": "y0"}, {"body": "Upper", "face": "y0"}]}},
{"command": "model.set.create", "params": {"name": "z0", "geometry": [{"body": "Lower", "face": "bottom"}]}},
{"command": "model.set.create", "params": {"name": "top", "geometry": [{"body": "Upper", "face": "top"}]}},
{"command": "model.material.create", "params": {"name": "Mat", "elastic": {"type": "isotropic", "young": 1000.0, "poisson": 0.3}}},
{"command": "model.section.create", "params": {"name": "lower", "set": "lower", "material": "Mat", "kind": {"type": "solid"}}},
{"command": "model.section.create", "params": {"name": "upper", "set": "upper", "material": "Mat", "kind": {"type": "solid"}}},
{"command": "interaction.contact.pair", "params": {"name": "interface", "main": "lower_top", "secondary": "upper_bottom"}},
{"command": "model.boundary_condition.create", "params": {"name": "x0", "type": "displacement", "target": {"set": "x0"}, "values": [0, null, null, null, null, null]}},
{"command": "model.boundary_condition.create", "params": {"name": "y0", "type": "displacement", "target": {"set": "y0"}, "values": [null, 0, null, null, null, null]}},
{"command": "model.boundary_condition.create", "params": {"name": "z0", "type": "displacement", "target": {"set": "z0"}, "values": [null, null, 0, null, null, null]}},
{"command": "model.boundary_condition.create", "params": {"name": "push", "type": "displacement", "target": {"set": "top"}, "values": [null, null, -0.02, null, null, null]}},
{"command": "model.step.create", "params": {"name": "Small", "procedure": {"type": "nonlinear_static", "nonlinear_geometry": false, "tolerances": {"force": 1e-10, "displacement": 1e-08, "energy": 1e-16}}, "boundary_conditions": ["x0", "y0", "z0", "push"], "loads": []}},
{"command": "model.step.create", "params": {"name": "Finite", "procedure": {"type": "nonlinear_static", "nonlinear_geometry": true}, "boundary_conditions": ["x0", "y0", "z0", "push"], "loads": []}},
{"command": "solve.nonlinear", "params": {"step": "Small"}, "id": "small"},
{"command": "solve.nonlinear", "params": {"step": "Finite"}, "id": "finite"}
]
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# Hertz line contact: cylinder on a flat (implicit mortar contact)
A steel cylinder of radius R = 10 mm pressed on a steel block (E = 210 GPa, ν = 0.3; mm, N, MPa)
in plane strain: a quarter model of the cylinder's lower part (a 2.5 mm wide block whose bottom
is the circular arc, graded towards the contact) on a 5 × 5 mm foundation, symmetric about
x = 0, one element thick with every node held in z. A pressure on the indenter's top carries
the load P = 2265.57 N/mm (per length of the whole cylinder) chosen so that Hertz's half-width is
b = 0.5 mm and the peak pressure p₀ = 2884.6 MPa. Soft springs (0.01 N/mm per node) hold the
indenter's top vertically until the contact closes. One nonlinear static step without nonlinear
geometry: small sliding, mortar contact of the round face (secondary) on the flat (main) by an
augmented Lagrangian.
@@ -0,0 +1,109 @@
{
"title": "Hertz line contact: a cylinder pressed on a flat (implicit mortar contact, plane strain)",
"kind": "theory",
"source": "H. Hertz, Über die Berührung fester elastischer Körper, J. reine angew. Math. 92:156–171, 1882; K. L. Johnson, Contact Mechanics, Cambridge University Press 1985, §4.3 (two-dimensional contact of cylindrical bodies, eqs. 4.45–4.49): b = √(4PR/(πE*)), p₀ = 2P/(πb), with 1/E* = 2(1 − ν²)/E for two bodies of one material and R the cylinder's radius on a flat",
"quantities": [
{
"id": "peak_pressure",
"quantity": "the largest contact pressure p₀ (at x = 0)",
"measure": {
"from": "solve",
"pointer": "/contacts/0/max_pressure/value"
},
"value": 2884.6153846153843,
"tolerance": {
"relative": 0.02
},
"reason": "p₀ = 2P/(πb) for the load per length P = 2265.57 N/mm, b = 0.5 mm; the contact width spans seven elements of the graded mesh"
},
{
"id": "normal_force",
"quantity": "the force across the contact (half model, 1 mm thick)",
"measure": {
"from": "solve",
"pointer": "/contacts/0/normal_force"
},
"value": 1132.7858125924733,
"tolerance": {
"relative": 0.002
},
"reason": "the pressure carries the whole load; the soft springs that hold the indenter before contact take a millionth"
},
{
"id": "pressure_x0296",
"quantity": "the contact pressure at the secondary node at x = 0.29594 (node 7)",
"measure": {
"command": "solve.probe",
"params": {
"step": "Press",
"nodes": [
7
]
},
"pointer": "/nodes/0/contact/0/pressure"
},
"value": 2325.066800691437,
"tolerance": {
"relative": 0.05
},
"reason": "p₀ √(1 − x²/b²) at the node; the nodal pressure (the node's normal force over the area it carries) averages the distribution over the node's elements"
},
{
"id": "pressure_x0367",
"quantity": "the contact pressure at the secondary node at x = 0.36701 (node 8)",
"measure": {
"command": "solve.probe",
"params": {
"step": "Press",
"nodes": [
8
]
},
"pointer": "/nodes/0/contact/0/pressure"
},
"value": 1959.0164149439815,
"tolerance": {
"relative": 0.1
},
"reason": "as at node 7, nearer the edge, where the elements round off the square-root fall of the pressure to zero at b"
},
{
"id": "pressure_x0633",
"quantity": "the contact pressure at the secondary node at x = 0.63325 (node 11, beyond the half-width b = 0.5)",
"measure": {
"command": "solve.probe",
"params": {
"step": "Press",
"nodes": [
11
]
},
"pointer": "/nodes/0/contact/0/pressure"
},
"value": 0.0,
"tolerance": {
"absolute": 1.0
},
"reason": "outside the contact the surfaces are apart: no pressure (an element beyond b, since the edge element carries part of the last closed node's pressure)"
},
{
"id": "syy_depth",
"quantity": "the vertical stress σ_yy under the centre of contact at depth 0.47127 (node 713)",
"measure": {
"command": "solve.probe",
"params": {
"step": "Press",
"nodes": [
713
]
},
"pointer": "/nodes/0/stress/1"
},
"value": -2099.1580228637245,
"tolerance": {
"relative": 0.04
},
"reason": "σ_z = −p₀ / √(1 + z²/b²) on the axis of a half-plane (Johnson 1985, eq. 4.49); the foundation is ten half-widths wide and deep, not a half-plane, and the stress is the nodal average of the elements around the node"
}
]
}
@@ -0,0 +1,29 @@
{
"note": "FieldCraft's accepted results for this case, written by `cargo xtask oracle --bless`. A result outside its band fails CI.",
"values": {
"normal_force": {
"band": 1.133036636011328e-6,
"value": 1133.0366360113278
},
"peak_pressure": {
"band": 2.891953889449524e-6,
"value": 2891.953889449524
},
"pressure_x0296": {
"band": 2.325066800691437e-6,
"value": 2257.8357909118563
},
"pressure_x0367": {
"band": 2.0784005834495077e-6,
"value": 2078.4005834495074
},
"pressure_x0633": {
"band": 1.0,
"value": -0.0
},
"syy_depth": {
"band": 2.0991580228637247e-6,
"value": -2059.819639241533
}
}
}
@@ -0,0 +1,23 @@
[
{"command": "mesh.block", "params": {"body": "Indenter", "kind": "hex8", "corners": [[0, 0, 0], [2.5, 0.3175416344814579, 0], [2.5, 3.0, 0], [0, 3.0, 0], [0, 0, 1.0], [2.5, 0.3175416344814579, 1.0], [2.5, 3.0, 1.0], [0, 3.0, 1.0]], "divisions": [20, 10, 1], "bias": [8, 8, 1], "edges": [{"corners": [1, 2], "arc": {"center": [0, 10.0, 0]}}, {"corners": [5, 6], "arc": {"center": [0, 10.0, 1.0]}}], "faces": {"3": "round", "5": "top", "6": "sym"}}},
{"command": "mesh.block", "params": {"body": "Foundation", "kind": "hex8", "corners": [[0, -5, 0], [5, -5, 0], [5, 0, 0], [0, 0, 0], [0, -5, 1.0], [5, -5, 1.0], [5, 0, 1.0], [0, 0, 1.0]], "divisions": [24, 14, 1], "bias": [10, 0.1, 1], "faces": {"3": "base", "5": "flat", "6": "sym"}, "merge": 0}},
{"command": "model.set.create", "params": {"name": "indenter", "geometry": [{"body": "Indenter"}]}},
{"command": "model.set.create", "params": {"name": "foundation", "geometry": [{"body": "Foundation"}]}},
{"command": "model.set.create", "params": {"name": "all", "geometry": [{"body": "Indenter"}, {"body": "Foundation"}]}},
{"command": "model.set.create", "params": {"name": "round", "geometry": [{"body": "Indenter", "face": "round"}]}},
{"command": "model.set.create", "params": {"name": "flat", "geometry": [{"body": "Foundation", "face": "flat"}]}},
{"command": "model.set.create", "params": {"name": "top", "geometry": [{"body": "Indenter", "face": "top"}]}},
{"command": "model.set.create", "params": {"name": "base", "geometry": [{"body": "Foundation", "face": "base"}]}},
{"command": "model.set.create", "params": {"name": "sym", "geometry": [{"body": "Indenter", "face": "sym"}, {"body": "Foundation", "face": "sym"}]}},
{"command": "model.material.create", "params": {"name": "Steel", "elastic": {"type": "isotropic", "young": 210000.0, "poisson": 0.3}}},
{"command": "model.section.create", "params": {"name": "indenter", "set": "indenter", "material": "Steel", "kind": {"type": "solid"}}},
{"command": "model.section.create", "params": {"name": "foundation", "set": "foundation", "material": "Steel", "kind": {"type": "solid"}}},
{"command": "interaction.contact.pair", "params": {"name": "hertz", "main": "flat", "secondary": "round"}},
{"command": "model.boundary_condition.create", "params": {"name": "sym", "type": "displacement", "target": {"set": "sym"}, "values": [0, null, null, null, null, null]}},
{"command": "model.boundary_condition.create", "params": {"name": "plane", "type": "displacement", "target": {"set": "all"}, "values": [null, null, 0, null, null, null]}},
{"command": "model.boundary_condition.create", "params": {"name": "base", "type": "displacement", "target": {"set": "base"}, "values": [null, 0, null, null, null, null]}},
{"command": "model.spring.create", "params": {"name": "hold", "type": "spring", "first": {"set": "top"}, "direction": {"dof": 2}, "stiffness": 0.01}},
{"command": "model.load.create", "params": {"name": "press", "type": "pressure", "set": "top", "magnitude": 453.1143250369893}},
{"command": "model.step.create", "params": {"name": "Press", "procedure": {"type": "nonlinear_static", "nonlinear_geometry": false, "max_iterations": 60}, "boundary_conditions": ["sym", "plane", "base"], "loads": ["press"]}},
{"command": "solve.nonlinear", "params": {"step": "Press"}, "id": "solve"}
]