forked from 1b-agent/fieldcraft-upstream
jyvikoandClaude Opus 5.5
2321d75cc6
The material point interface returns the Kirchhoff stress and the spatial tangent of its Lie derivative from the deformation gradient, with per-point history committed by the solver: St Venant–Kirchhoff (pushed forward from S = D E) and the decoupled compressible neo-Hookean with its isochoric and volumetric parts. Total Lagrangian solids (tet4, tet10, wedge6, hex8, hex20 full and reduced) and plane strain and axisymmetric elements give internal forces and the consistent tangent with its geometric stiffness; hybrid solids use the Simo–Taylor–Pister three-field formulation on the existing pressure fields. Incompatible modes and plane stress are refused by name. Follower pressure on faces and 2D edges with its load stiffness. Every tangent is checked against central differences of its forces. Co-Authored-By: Claude Opus 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm