4C version v2026.2.0

What's Changed

Breaking Changes

• Disable old solid time integration in ssi by @c-p-schmidt in #1689
• Change default solid time integration setting by @c-p-schmidt in #1715
• Remove wall elements from 4C by @amgebauer in #1976
• Remove CALC_NECKING_TSI_VALUES by @rjoussen in #1732
• [beaminteraction] Remove bruteforce search from beam contact and make ArborX a mandatory dependency for beam-contact-interaction by @maxfirmbach in #1752
• [solver] Remove AZCONV parameter by @maxfirmbach in #1933
• Rename master/slave to source/target in contact module by @lauraengelhardt in #1927
• [TSI] Remove tsi cross output and old writers by @rjoussen in #1975
• Remove untested penalty-based 3D multipoint constraint by @lauraengelhardt in #1774

Dependency Changes

• Add mumps as direct solver by @c-p-schmidt in #1815
• Update superlu_dist dependency to version 9.2.1 by @c-p-schmidt in #1869
• [Qhull] Make it an optional dependency by @maxfirmbach in #1931
• [infrastructure] Rework Trilinos configure process and add TPL dependency variables by @maxfirmbach in #1930
• [MIRCO] Update hash by @maxfirmbach in #1932

Miscellaneous

• Beam to beam point couplings with Lagrange multipliers by @isteinbrecher in #1691
• Implement 1D pipeflow for pulmonary system by @engstlerL in #1683
• Add junction implementation in 1D pipeflow by @engstlerL in #1717
• Add terminal units in 1D pipe flow implementation by @engstlerL in #1781
• Introduction of NOX in Reduced Lung by @maxiludwig in #1807
• [ReducedLung] Implement model registry and factory for terminal units by @bgoderbauer in #1929
• [ReducedLung] Implement model registry and factory for airway models by @bgoderbauer in #1960
• Add naive implementation of an orthotropic material by @maxfirmbach in #1700
• Introduce growth and remodeling as ssi problem by @tuchpaul in #1805
• Enable intensive scalar transport in ssi by @tuchpaul in #1792
• Introduce time dependent anisotropic inelastic deformation gradient by @c-p-schmidt in #1926
• Enable mesh fiber input for muscle materials by @lauraengelhardt in #1806
• Use EvaluationContext in ElastHyper to enable mesh fiber input for Blemker material by @lauraengelhardt in #1808
• Add temperature parameters for RefJC viscoplasticity, along with GP output by @dragos-ana in #1879
• Enable 2D solid elements (using wall theory) by @amgebauer in #1894
• Enable EAS in 2D SOLID elements by @amgebauer in #1903
• Enable nurbs in 2D SOLID elements by @amgebauer in #1902
• Enable 2d solidscatra elements by @amgebauer in #1920
• Add infrastructure for python bindings in 4C by @amgebauer in #1091
• Add external python predictor by @danielwolff1 in #1898
• Add Python-based surrogate model for rough surface contact by @mayrmt in #1735
• [Particles] Introduce constraints feature to the particles framework by @vovannikov in #1729
• [SPH] Multiple open (Dirichlet and Neumann) boundaries by @vovannikov in #1856
• Add pre-crack for BB-Peridynamics by @alhermann in #1881
• Switch 2D/3D peridynamics by @georghammerl in #1775
• Change peridynamic contact formulation by @georghammerl in #1789
• Add per particle dbcs by @georghammerl in #1895
• [discretization] Add Clement Interpolant by @maxfirmbach in #1738
• [beaminteraction] Add augmented system formulation for beam-solid volume meshtying by @maxfirmbach in #1750
• [beaminteraction] Individual augmentation scaling parameters by @isteinbrecher in #1897
• [beaminteraction] Avoid binning based partitioning by @maxfirmbach in #1523
• Add two half pass method to SBIP approach for beam potential interactions by @davidrudlstorfer in #1957
• Make the new structure time integration compatible with saddle-point contact/meshtying preconditioners (MueLu) by @PhilipOesterlePekrun in #1744
• [constraint framework] Add nullspace orthonormalization by @maxfirmbach in #1822
• [structure] Add partial krylov projector by @maxfirmbach in #1819
• [LinAlg] Add locally replicated maps and orthonormalization for multi vector columns by @maxfirmbach in #1782
• [LinAlg] Add rank m correction method by @maxfirmbach in #1839
• PoroElast framework: enable Gauss point output / fix case output by @dragos-ana in #1770
• Add option to include bodyforce contributions in the solid field in porofluid_pressure_based problem types by @lkoeglmeier in #1835
• Enable optional vtk output of shell7p thickness director and thickness by @mairehenke in #1748
• Use external node set names in condition definitions by @rjoussen in #1688
• Feature: Support named point sets in VTU files by @bennoschoenstein in #1918
• Allow to specify cell data for element creation when reading mesh by @isteinbrecher in #1763
• Implement lazy conversion of mesh data to target types by @amgebauer in #1809
• Introduce specific solver for the calculation of the initial potential field by @c-p-schmidt in #1850
• [solver] Unify preconditioner xml file parameter by @maxfirmbach in #1935
• Allow to export timings as yaml by @amgebauer in #1979
• Make control file writing crash safe by @georghammerl in #1870
• Update deal.II context with fe capabilities in FEValues fashion by @marksidoro in #996
• Add additional NOX status test for beaminteraction using Lagrange multipliers by @dharinib98 in #1660

Contributors

List of all contributors who authored, committed, reviewed, or commented on accepted pull requests for this release.

• Authors / Committers: @PhilipOesterlePekrun @alhermann @amgebauer @bennoschoenstein @bgoderbauer @c-p-schmidt @danielwolff1 @davidrudlstorfer @dharinib98 @dragos-ana @eulovi @georghammerl @ischeider @isteinbrecher @jeremylt @lauraengelhardt @lkoeglmeier @m-frey @mairehenke @marksidoro @maxfirmbach @maxiludwig @mayrmt @ppraegla @reginabuehler @rjoussen @sebproell @tuchpaul @vovannikov

• Reviewers: @PhilipOesterlePekrun @alhermann @amgebauer @bennoschoenstein @bgoderbauer @c-p-schmidt @danielwolff1 @davidrudlstorfer @dharinib98 @dragos-ana @engstlerL @eulovi @georghammerl @gilrrei @ischeider @isteinbrecher @jeremylt @knarfnitram @lauraengelhardt @lkoeglmeier @m-frey @mairehenke @marksidoro @maxfirmbach @maxiludwig @mayrmt @ppraegla @reginabuehler @rjoussen @sebproell @slfuchs @tuchpaul @vovannikov @vryy

New Contributors

Thanks to first-time contributors to 4C!

• @engstlerL made their first contribution in #1683
• @jeremylt made their first contribution in #1843
• @alhermann made their first contribution in #1881
• @bennoschoenstein made their first contribution in #1918

Full Changelog: v2026.1.0...v2026.2.0