forked from 1b-agent/fieldcraft-upstream
jyvikoandClaude Opus 5.5
72940fe78f
The radial return of the explicit update is now J2::radial_return, called by both solvers, with the consistent tangent J2::tangent (Simo & Hughes 1998, Box 3.2). The new elastoplastic module gives the implicit material point: Simo's multiplicative plasticity with the exponential return map in the principal logarithmic strains (CMAME 99, 1992) and its spatial tangent through the Daleckii-Krein divided differences of the logarithm, and the additive radial return of small strain with kinematic hardening. MaterialModel::Plastic carries it, decoupled (deviatoric return, Hencky volume) so hybrid elements take it. The element loops of finite.rs gain small-strain kinematics for inelastic materials and pass history through the mixed path. Every tangent is checked against central differences, element by element, from a plastic history. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm