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Upcoming release

The release notes for the upcoming release are:

New features

  • Restart and initial conditions

    • Binary stress-field transfer: Added *Restart write, stress to write the final committed integration-point stress field at the end of a step. The binary field can be imported into a new analysis with an exactly matching mesh using *Initial conditions, type=stress, file=<filename>, mesh=matching. This supports calculating an equilibrium stress field with a simple constitutive model and reusing it as the initial stress field for a subsequent analysis with a more advanced model. Only stresses are transferred; constitutive state variables and other material-specific history have to be initialized separately. See Restart and Initial stress.

  • Elements

  • Embedded region

    • Embedded beam, interaction: Embedded beam implementation for linear structures with dominant skin friction and negligible base resistance such as anchors, micro piles or nails.

  • Loads:

    • Relative Springs: Springs representing a support installed only at some later stage — a strut installed after an excavation step has already deflected the retained wall, for instance — should be force-free at the moment of installation the support, not already carrying the load corresponding to whatever deformation occurred before it existed. A new keyword relative takes the deformation history of springs into account. See Reference Manual and the Theory Manual.

  • Constraints

    • Linear equation constraints: Extended *Equation with the linear type. A homogeneous relation containing two or more user-defined DOF/factor pairs can now be applied independently to every node of a node set. This supports direction-dependent constraints such as zero normal displacement on inclined boundaries or piecewise representations of curved boundaries. See the Theory Manual.

  • Constitutive models

    • Hardening Soil: The Hardening Soil model with Matsuoka-Nakai failure surface with benchmarks given in the Benchmark Manual.

    • Hardening Soil Bricks: The Hardening Soil model with small strain extension.

    • Ta-Ger: Added the Ta-Ger sand model, a constitutive model for sand based on an explicit elastoplastic matrix, Bouc-Wen-type hysteresis, Rowe-type dilatancy, Bolton's relative dilatancy index and stress-induced anisotropy. The model is intended for monotonic and cyclic loading of sands, including contractive and dilative response, pore-pressure build-up under undrained conditions and liquefaction-related stress paths.

    • Bathytropic Elasticity: Added a depth-initialised isotropic elastic model that derives the local shear modulus and Young's modulus from prescribed shear-wave-velocity and density profiles. The modulus is stored at the first constitutive evaluation and remains constant afterwards. See the Reference Manual and Theory Manual.

  • Contact

  • Graphical mini tools

    • CPT Model Generator: Added a graphical tool for generating, running, and evaluating axisymmetric cone penetration test models. The documentation page includes a Windows executable and an embedded demonstration video. The tool supports geometry and mesh generation, layered soil profiles, hypoplastic and Mohr-Coulomb materials, separate CPT-body and friction-sleeve contact parameters, numgeo input generation and execution, and the evaluation of tip resistance, sleeve friction, and friction ratio.

General modifications

  • Elements

    • Beam elements: Density now contributes consistently to body forces, not only to the mass matrix

  • Convergence criteria:

    • The dof-based convergence evaluation was updated to evaluate residual and reference force norms on unconstrained degrees of freedom.

    • The documentation of the dof-based convergence criteria was updated to reflect the current implementation, including the negligible solution response criterion, negligible unbalance energy criterion, nonquadratic-convergence relaxation and the current default tolerances.

  • Step termination

    • The evaluation of *Termination criteria was revised. Instead of inferring the comparison direction from the sign of the prescribed termination value, numgeo now stores reference values at the beginning of the step and checks whether the prescribed value is crossed relative to this reference state.

    • The termination check now accounts for a numerical tolerance based on machine precision and the magnitudes of the reference value, current value and prescribed termination value.

    • With this release, numgeo also allows to define multiple *Termination criteria per step. The first one to be fulfilled terminated the step.

  • Solver

    • With the upcoming release the use of the Simple solver is restricted to models with no more than 10 elements. For models with more elements, the solver is automatically changed to Pardiso and a warning is issued.

  • Speed-up starting time of large simulations

    • The starting time for large models has been significantly reduced. For a finite element model with approx. 1 Mio. nodes and more than 0.42 Mio. elements, the start-up time (reading model from input file + building the database and checking inputs) has been reduced from over 1 h to now only 5 seconds.

Resolved bugs

  • Equation constraints

    • The penalty residual and tangent now use the stored coefficients consistently for every equation term. This corrects equation definitions with non-unit factors and generalises assembly from two-term constraints to an arbitrary number of terms.

  • Output

    • Fixed some issues with binary vtk output

  • Benchmark Manual

    • SANISAND-2: Remove deprecated tangent_stiffnes optional parameter from material definition. Unfortunately this led to an error when using the model in combination with the HCA model (HCA_SANISAND-2)

Manuals

  • Benchmark Manual

  • Reference Manual

    • Equation: Added the linear equation type for homogeneous same-node constraints with user-defined coefficients and documented the locally scaled penalty multiplier.

    • Restart: Added the step-level *Restart write, stress option for binary output of the final committed integration-point stress field.

    • Initial stress: Added File=<filename>, Mesh=matching for importing a binary stress field written by *Restart write, stress.

    • BC-HYPO-IGS-SF: Bio-Cemented Hypoplasticity + Intergranular Strain + Semi-Fluidized State and Fabric Change Effects.

    • Controls: Updated dof-based convergence-control parameters and default values.

    • Ta-Ger: Added material input syntax, parameter description, state-variable output and implementation notes for the Ta-Ger sand model.

    • *Termination: Added documentation of stress- and strain-based early termination syntax and clarified that the comparison direction is determined from the reference state at the beginning of the step.

    • Beam elements: Updated manual, removed release announcement

    • Hardening Soil Bricks: Hardening soil model with Matsuoka Nakai failure surface and Bricks small strain extension

    • Springs: Added relative option, added documentation for userdefined tabular springs

    • Embedded region, interaction: new embedded region implementation for coupling line (guest) elements - trusses or beams - to a region of continuum (host) elements using distributed interface springs, following the embedded beam concept frequently used for grouted anchors, soil nails and micro piles.

    • Bathytropic elasticity: Added material input syntax, parameter definitions, coordinate and unit conventions, one-time stiffness initialisation, state-variable information and guidance for dynamic-density consistency.

  • Theory Manual

    • Multi-point constraints: Updated the penalty formulation for arbitrary equation coefficients and terms, documented the local tangent-stiffness scaling and added the set-based linear equation type.

    • Convergence criteria: Updated description of dof-based convergence controls.

    • Ta-Ger: Added the theoretical background of the Ta-Ger sand model, including the explicit elastoplastic matrix, mapping variable, hardening exponent, bounding and phase-transformation stress ratios, Bolton-index calibration and stress-induced anisotropy.

    • Early termination criteria: Added theoretical background for stress- and strain-based step termination criteria, including the definition of reference values, the crossing criterion for loading and unloading paths, and the numerical tolerance used in the evaluation.

    • Hardening Soil Bricks: Hardening soil model with Matsuoka Nakai failure surface and Bricks small strain extension

    • Springs: Added documentation

    • Embedded region, interaction: new embedded region implementation for coupling line (guest) elements - trusses or beams - to a region of continuum (host) elements using distributed interface springs, following the embedded beam concept frequently used for grouted anchors, soil nails and micro piles.

    • Bathytropic elasticity: Added the depth-dependent shear-wave-velocity and density profiles, derivation of the elastic moduli, one-time initialisation algorithm, small-strain strain-energy potential, elastic Jacobian and implementation limitations.

    • Parallel assembly

  • Tutorial Manual