forked from 1b-agent/fieldcraft-upstream
jyvikoandClaude Opus 5.5
17b2c837f2
Elements of a plastic material take the J2 material point: total Lagrangian with nonlinear geometry, the small-strain loops without (elastic elements keep their linear stiffness, so elastic results do not move). The plastic history is committed per converged increment. Increments follow the step's load path, ending at its points, the extrapolated predictor scaled by the change of the load factor. Steps with path-dependent materials start an increment without a predictor from the tangent predictor (the prescribed motion spread through the converged tangent), and a first tangent that is not positive definite is a cutback when the undeformed model's is. Refused by name: the Johnson-Cook rate term (a static step has no time) and kinematic hardening at finite strain; damage, erosion and adiabatic heating are left out with a warning. Results carry the equivalent plastic strain at the integration points (solve.probe, the step summary). LS-DYNA writes a load path as the step's curve; Abaqus refuses it and a plastic deck of several general steps (Abaqus carries the plastic state between them). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm