forked from 1b-agent/fieldcraft-upstream
e900f41ce3
* Heat transfer and thermal stress: thermal materials, temperature BCs, heat loads, heat transfer and coupled temperature–displacement steps, solve.heat
Model: Material.thermal (conductivity, specific heat, expansion, isotropic or
per axis; reference temperature), BoundaryCondition::Temperature (dof 11),
loads SurfaceFlux, Convection, HeatSource and Temperature (a field in static
steps), procedures HeatTransfer { transient (θ-method) } and
CoupledTemperatureDisplacement; checks for missing conductivity/specific
heat/expansion. fem: heat conduction kernels (conductivity, capacity,
source, face flux/film, heat flux) on the DofLayout (one T per node), thermal
strain load and stress D(ε − ε_th) for every solid formulation incl.
incompatible modes. Solver: steady and transient heat transfer, thermal loads
in static steps, coupled steps (exact one-way coupling). Engine: solve.heat,
temperature/heat-flux result fields, probes. Decks refuse heat transfer by
name. Analytic verification: slab, source+convection/flux, thick cylinder,
erfc semi-infinite solid, free/constrained expansion, bimetal strip, coupled
step.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm
* thermal: strains in 2D elements and explicit dynamics
Plane::thermal_load and stresses_with for plane stress (εzz free), plane
strain (σzz = −D₃·ε_th) and axisymmetric elements, incompatible modes
included; the solver's 2D kernels take them. Explicit dynamics turns a
step's temperature loads into a per-element thermal strain rate (reached
linearly over the step) subtracted from each strain increment, so it feeds
J2 and Johnson–Cook updates. Verified: free expansion in every 2D theory
and element, a biaxially held plate, an explicit free bar (ΔL = αΔT L,
stress-free) and a clamped bar at −EαΔT, capped at the yield stress with
perfect plasticity.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm
* clippy
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm
* thermal: trusses take the axial thermal strain; keep the roadmap's M7 line
Truss::thermal_load and stresses_with project the thermal strain on the
member's tangent (Σ αₖ tₖ² ΔT); the static solver applies them to rod2/rod3
(#38). Explicit trusses take none yet and a warning says so.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm
---------
Co-authored-by: jyviko <2501648+jyviko@users.noreply.github.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
89 lines
6.3 KiB
Markdown
89 lines
6.3 KiB
Markdown
# Element library
|
||
|
||
ModelCraft's finite element library (`crates/fem`), family by family, with status. The scope is
|
||
modelled on what a full CAE code offers (Abaqus's element library is the reference for breadth);
|
||
names, formulations and tests are our own, written from the published literature. Deck writers map
|
||
each of our elements to each solver's name (see `crates/decks`). Simple elements first: 1D and 2D,
|
||
then shells, special-purpose and multiphysics elements.
|
||
|
||
Status: **done** (on main, verified against analytic solutions), **in progress** (an agent task is
|
||
open), **planned**.
|
||
|
||
Every element builds on the shared foundation of docs/fem.md: it declares its nodal degrees of
|
||
freedom (`DofKind`: translations, rotations, temperature, pressure) and condensed internal ones
|
||
(`ElementDofs`), the solvers number them with `DofLayout`, and its interpolation comes from the
|
||
shape-function library (`Basis`: line2/3, tri3/6, quad4/8/9, tet4/10, wedge6/15, pyramid5,
|
||
hex8/20/27 with first and second derivatives).
|
||
|
||
## Point and discrete elements
|
||
|
||
| Element | Use | Status |
|
||
|---|---|---|
|
||
| Point mass | Lumped mass at a node or reference point (isotropic or per direction) | done (implicit, explicit; Abaqus MASS, Nastran CONM1, LS-DYNA ELEMENT_MASS; per direction: Nastran only) |
|
||
| Rotary inertia | Inertia tensor at a 6-DOF node | done (implicit; Abaqus ROTARYI, Nastran CONM1, LS-DYNA ELEMENT_INERTIA; explicit when it has rotations) |
|
||
| Spring to ground / two-point spring | Linear spring in a fixed direction or along the line of nodes | done (implicit, explicit translational; Abaqus SPRING1/2/A, Nastran CELAS2, LS-DYNA ELEMENT_DISCRETE; skew fixed directions: LS-DYNA only) |
|
||
| Dashpot to ground / two-point | Linear viscous damper (dynamic steps; ignored in static) | done (explicit; ignored with a warning in static and frequency steps; Abaqus DASHPOT1/2/A, Nastran CDAMP2, LS-DYNA ELEMENT_DISCRETE) |
|
||
| Nonstructural mass | Mass spread over a region without stiffness | planned |
|
||
| Connectors | Kinematic joints (hinge, slot, universal…) with elasticity, damping, stops | planned (M7) |
|
||
|
||
## 1D elements
|
||
|
||
| Element | Use | Status |
|
||
|---|---|---|
|
||
| Truss, 2-node (2D and 3D) | Axial members, cables (compression allowed) | done (rod2: implicit, in plane models with their two unknowns per node; explicit, corotational under nonlinear geometry; Abaqus T3D2 / T2D2, Nastran CROD, LS-DYNA truss beam (3D models)) |
|
||
| Truss, 3-node (2D and 3D) | Curved axial members | done (rod3: implicit, plane models too; explicit with small displacements; Abaqus T3D3 / T2D3; no Nastran or LS-DYNA counterpart) |
|
||
| Beam, 2-node Timoshenko, 3D | Frames, stiffeners; shear deformable | done (exact interdependent interpolation, profile properties, orientation vector; `modelcraft_fem::beam`) |
|
||
| Beam, 2-node Euler–Bernoulli (cubic), 2D and 3D | Slender frames; exact for end-loaded prismatic members | planned (1D elements II) |
|
||
| Beam, 3-node Timoshenko (quadratic), 2D and 3D | Curved and stocky beams | planned (1D elements II) |
|
||
| Beam, 2D (planar frames) | In-plane frames with 3 DOFs per node | planned (1D elements II) |
|
||
| Pipe / elbow | Pipes with internal pressure, ovalisation | planned (1D elements II) |
|
||
| Open-section beams with warping | Thin-walled sections in torsion | planned |
|
||
| Rebar / stringers | Reinforcement along edges or embedded | planned |
|
||
|
||
## 2D elements
|
||
|
||
| Element | Use | Status |
|
||
|---|---|---|
|
||
| Plane stress tri3, tri6, quad4, quad8 | Thin plates loaded in their plane | in progress (2D elements) |
|
||
| Plane strain tri3, tri6, quad4, quad8 | Long sections (dams, tunnels, extrusions) | in progress (2D elements) |
|
||
| Axisymmetric tri3, tri6, quad4, quad8 | Revolved solids (shafts, vessels, discs) | in progress (2D elements) |
|
||
| Incompatible-mode and reduced-integration quads | Bending-accurate and cheap variants | in progress (2D elements) |
|
||
| Generalized plane strain | Plane strain with a free out-of-plane strain | planned |
|
||
| Axisymmetric with twist | Revolved parts under torsion | planned |
|
||
| Axisymmetric shells (2-node, 3-node) | Thin revolved shells (tanks, domes) | planned |
|
||
| Hybrid (mixed u–p) variants | Nearly incompressible materials | planned |
|
||
|
||
## Shells and membranes
|
||
|
||
| Element | Use | Status |
|
||
|---|---|---|
|
||
| Shell quad4 (MITC4), triangle (locking-free) | Thin and thick shells | done (flat MITC4 and MITC3 with a Hughes–Brezzi drilling rotation; `modelcraft_fem::shell`) |
|
||
| Shell quad8 / tri6 | Curved thick shells | planned |
|
||
| Continuum shells (8-node, on swept hex) | Thick-to-thin shells, composites through thickness | planned (M8) |
|
||
| Membranes (tri3, quad4, quad8) | Fabrics, inflatables, skins without bending | planned |
|
||
| Surface elements | Massless surfaces for loads and contact | planned |
|
||
| Composite layups on shells | Ply tables, orientations | planned (M8) |
|
||
|
||
## 3D solids
|
||
|
||
| Element | Use | Status |
|
||
|---|---|---|
|
||
| tet4, tet10 | Free meshes of any part | done |
|
||
| hex8 (full, incompatible modes), hex20 (full, reduced) | Structured and swept meshes | done |
|
||
| wedge6 | Swept meshes from triangles, transitions | done |
|
||
| hex8 one-point with hourglass control, nodal-pressure tet4 (explicit) | Explicit dynamics | done |
|
||
| wedge15, pyramid5/13 | Quadratic transitions, tet–hex transition | planned (M5); wedge15 and pyramid5 shape functions done |
|
||
| Hybrid (mixed u–p) solids | Nearly incompressible materials (rubber) | in progress (FEM foundation, phase C); pressure DOF kind done |
|
||
| Modified quadratic tet (tet10 for contact/plasticity) | Robust quadratic tets | planned |
|
||
|
||
## Special-purpose and multiphysics
|
||
|
||
| Element | Use | Status |
|
||
|---|---|---|
|
||
| Cohesive (2D, 3D) | Adhesive layers, delamination | planned |
|
||
| Gasket | Through-thickness gasket behaviour | planned |
|
||
| Infinite elements | Unbounded domains | planned |
|
||
| Heat transfer (all shapes), coupled temperature–displacement | Thermal and thermal-stress analyses | done for solids (tet4/10, wedge6, hex8/20: steady and transient conduction, flux, convection, sources; coupled temperature–displacement); thermal strain in solids, trusses, 2D elements (plane stress, plane strain, axisymmetric) and explicit dynamics (one-point hex8, nodal-pressure tet4, with plasticity); 2D/shell/beam conduction and shell/beam thermal strain planned |
|
||
| Acoustic | Fluid acoustics, structural–acoustic coupling | planned |
|
||
| Rigid elements | Rigid bodies from meshes | planned (M7) |
|