forked from 1b-agent/fieldcraft-upstream
jyvikoandClaude Opus 5.5
8871f6721d
Frictionless contact pairs enforced by an augmented Lagrangian: nodal pressures from the mortar weighted gaps, Uzawa updates after each converged increment until the gaps are within 1e-5 of the element thickness, and the consistent tangent (outer products of the weighted gap gradients and the pressure-weighted Hessians from the automatic differentiation of the mortar integrals). Finite sliding searches and integrates on the current configuration every evaluation; without nonlinear geometry the pairs and their mortar integrals are fixed in the reference configuration (small sliding, linear and exact). The tangent's pattern takes the face pairs' blocks; the step cuts back when the active set chatters. Initial overclosure is offset or refused; general contact, 2D models and arc length are refused by name; the linear analyses refuse contact by name instead of the mesh. With contact the convergence force scale comes from the converged states, the loads and the current state. The loads-and-reactions balance check takes the nodal reactions into its scale (no spurious warning for a part squeezed between held faces). Tests: the contact patch test on non-matching hex8/tet4 meshes (exact with small sliding, to 1e-4 with finite sliding), Hertz cylinder on a flat (peak pressure within 3%, half-width bracketed) with quadratic Newton convergence, overclosure, thread-count determinism and the refusals; Hertz sphere on a flat (heavy). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo