FluxFEM

FluxFEM 0.3.10 FluxFEM 0.3.10 is a broad structural-mechanics release. It collects the recent work on structural elements, coupling constraints, plate/shell helpers, mixed-dimensional models, Craig-Bampton ROM workflows, contact utilities, and nonlinear- material diagnostics. Capability Overview Core FEM Weak-form-centered assembly JAX-based residual/Jacobian workflows SciPy/NumPy-oriented sparse assembly paths Hex/tet continuum spaces Dirichlet handling Mass assembly VTU export utilities Structural Elements Spring helpers Mass helpers Dashpot helpers 2D bar/truss helpers 3D bar/truss helpers 2D frame helpers 3D Euler-Bernoulli beam helpers Beam point loads Beam distributed/uniform loads Truss point loads Consistent/lumped mass support where available Constraints and Coupling MPC-style constraint rows Tie constraints Rigid/RBE2-style constraints RBE3-style distributed coupling Distributed coupling rows Bolt preload helpers Component-selective slave/reference coupling Solid-beam RBE3-style coupling Solid-truss RBE3-style coupling Solid-shell translational ties Nonmatching shell-solid translational interpolation Solid-shell patch-to-edge RBE3-style coupling Plate and Shell Q4 Mindlin/Reissner-Mindlin plate helpers Q4 Reissner-Mindlin shell helpers Reduced shear integration Full shear integration MITC4-style shear option Plate/shell stiffness assembly Plate/shell mass assembly Shell examples with 2D and tilted 3D coordinates Shear-locking benchmark tutorials Shell-solid cantilever comparison tutorial Dynamics Linear Newmark workflows Lumped spring-mass-dashpot examples Beam tip spring/dashpot dynamics Reduced-coordinate Newmark utilities Mass/stiffness projection workflows Craig-Bampton ROM CB basis construction from assembled FE systems Stiffness/mass matrix reduction Sparse-preserving projection utilities Matrix-free reduced operator actions Retained interface/contact DOF workflows Multi-field CB builder workflows Beam/truss/plate/shell ROM coverage Solid-shell, solid-beam, and solid-truss CB checks Mixed solid + shell + beam CB-ROM checks Static, modal, and Newmark-history regression coverage Contact-ready retained interface examples Contact and Interfaces Penalty-style contact helpers Active contact update loops Node/surface contact utilities Paired-surface contact utilities Contact diagnostics KKT/contact builder paths Mortar-oriented utilities Two-body contact VTU tutorial Supported-box contact tutorials Contact/CB-ROM example workflows Nonlinear Materials Neo-Hookean hyperelastic residual examples Small-strain J2 material-point return mapping J2 FE quadrature-state helpers J2 load-step helper with committed history updates J2 VTU output J2 load-history CSV output J2 Newton-iteration CSV output J2 dtype defaults aligned with active JAX x64 configuration J2 convergence diagnostics J2 material-point tangent finite-difference tests J2 FE residual Jacobian finite-difference checks Tutorials and Documentation Roadmap implementation status added to README Beam/truss tutorials Plate/shell tutorials Shell-solid coupling tutorials Contact tutorials Craig-Bampton ROM tutorials Nonlinear J2 tutorial PETSc shell solver tutorial VTU-output examples for inspection Notes RBE2/RBE3 helpers are FluxFEM-style tested constructions, not complete Nastran card-compatible implementations. Current shell helpers focus on flat/planar Reissner-Mindlin-style workflows; general curved shell kinematics and layered shells remain future work. J2 plasticity is now well covered for material-point and small FE verification cases, but production restart/output and broader material lifecycle APIs remain future work. Large-sliding/frictional contact and full mortar contact lifecycle management remain active development areas. Polished support-layout optimization, shape-parameter optimization, and nonlinear/contact ROM workflows are still good next targets.