forked from 1b-agent/fieldcraft-upstream
5ebb9f16dc
The isotropic elasticity splits into D_dev + K m mᵀ; an element-wise discontinuous pressure is condensed out (p̂ = K M⁻¹ Gᵀ u), leaving K_dev + K G M⁻¹ Gᵀ (Hughes §4.3–4.5). Q2–P1disc and P2–P0 are inf-sup stable; Q1–P0 does not lock; tet4 and wedge6 still lock and are refused, as are orthotropic materials (named at the section). ElementDofs counts the condensed pressures. Verified: element patch, rigid modes and totals for every hybrid kind, a block in uniaxial strain at ν = 0.4999 (exact), Lamé's cylinder in plane strain at ν = 0.4999 (hex20 1e-5, tet10 1.3e-3, hex8 2.5e-3 vs the locking displacement hex8 at −80 %). Every non-hybrid result of the test suites hashes identically before and after. 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>