forked from 1b-agent/fieldcraft-upstream
jyvikoandClaude Opus 5.5
9a8ae50bca
K_σ = ∫ (∇N_a · σ ∇N_b) I dV for a stress state at the stiffness points (solids, plane and axisymmetric elements with the hoop term), for linear buckling. Checked: uᵀK_σu = σ V for a uniform stress on a distorted hex20 and a plane strain quad8, rigid translations in its null space. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>