Altair Radioss 2020 Release Notes

New Features

Radioss Entities:

/MERGE/RBODY: New option to merge rigid bodies together. This option can also add a slave node or node set to an existing rigid body. Simple options are available to manage the rigid body master node and the mass update. Only the master rigid body is kept in the model for the computation.
/FUNCT_SMOOTH: New Smooth amplitude curves. The curve is described using points that are connected using a cubical function with zero tangent at the points. Scaling and offset options are included in the function. This option can be used for loads and imposed motion.
/SENSOR/ENERGY: New sensor where the activation is controlled by the internal or kinetic energy of a user-defined part or subset.

Computation control:

/ALE/SOLVER: Default ALE formulations switches to surface integration for internal forces (for the legacy ALE solver). It is better than CAA since CAA uses shape function (and its limitation) for deviatoric stress. The new keyword allows to recover older formulations.

Material, failure model, equation of states:

/EOS/NASG: New Equation of State (EOS) from O. Lemetayer and R. Saurel based on the Noble-Abel and Stiffened Gas formulations.
/MAT/PLAS_PREDEF: New material with predefined value for the yield stress, ultimate stress, and corresponding strain. Only the material name needs to be entered.
/MAT/LAW103: New material law based on Hansel-Spittel formulation. This material is dedicated to forming analysis.
/MAT/LAW106: New Johnson-Cook material law with Young's modulus and Poisson's ratio can be defined as a function of temperature. This material is designed for Additive Manufacturing applications.
/FAIL/ALTER: New advanced nonlinear stress-based failure criteria for glass applications such as a windshield.
/FAIL/COCKCROFT: New failure model based on Cockcroft-Latham formulation.
/FAIL/VISUAL: New failure model to track maximum stress or strain in an element. The output is damage as a function of the minimum and maximum input values. The output is for visualization only. There is no damage to the stress tensor or element deletion.

Animation output:

/H3D/NODA/SSP: New visualization to display the speed of sound on the outer and inner surface of finite volume airbag (/MONVOL/FMVBAG1).
/H3D/ELEM/COLOR: New color function output for Multi Material ALE laws. The phase or sub-material is displayed with a color corresponding to the phase sub-material number.
/H3D/ELEM/VECT: New H3D output to display the contact force in the finite volume cell. This is used with contact interface /INTER/TYPE18 and ALE material /MAT/LAW151.

Time history output:

/TH/QUAD: Strain output for 2D solid elements (/QUAD) in the time history file for both isotropic and orthotropy element properties.

Enhancements

General controls:

/ADYREL

New option to define a starting time (T_start) and final time (T_stop) for automatic dynamic relaxation.
Improvement for some gravity loading cases.
Convergence improvement for a specific model with concentrated loads (/CLOAD).

/DT/ALE

The value of DT_MIN is now taken into account to stop the computation when the time step is smaller than DT_MIN. This is only for /ALE/EULER cells.

/ALE/MUSCL

New flag IFLAG=1 to reconstruct only volume fraction fields when used with /MAT/LAW151.

/UPWIND

New warning message is displayed in case eta3 is used. This method shows some limits and may lead to numerical instability and energy conservation issue. It is recommended to use the /ALE/MUSCL formulation.

Contact interfaces:

/INTER/TYPE7

Improvement of the domain decomposition for TYPE7 interfaces during self-impact.

/INTER/TYPE11

New option Irem_gap=2 to automatically manage self-impact in the edge to edge treatment.

/INTER/TYPE18

The ALE side can now be defined using a group of bricks (/GRBRIC) to allow compatibility with all ALE multi-fluid materials (/MAT/LAW151). The old format using node sets is still supported by the Radioss Starter.

/INTER/TYPE19

New parameters are added:

Irem_gap=2: To avoid incorrect self-impact in models with small elements relative to the contact gap thickness for edge to edge and node to surface contact.
%mesh_size: To modify the contact gap scale factor.
Irem_i2: To remove contact slaves nodes that are also slaves in a tied interface.

/INTER/TYPE21

New variable P_skid to compute the skid line prediction value printed with the output /H3D/NODA/SKID_LINE.

/INTER/TYPE25

Computation of initial penetrations vs external surface of solid parts (INACTI=5 and -1). Previously, initial penetrations were computed only for shell elements.

/FRICTION

New orthotropic friction model in the contact interfaces TYPE7, 19, 24 and 25.

/FRIC_ORIENT

New option to define the orthotropic friction direction in a part with an isotropic material. The orthotropic friction direction automatically is the same as the one defined in the orthotropic material.

/INTER/SUB

Support for contact interface /INTER/TYPE25 was added. Surface to surface and node to surface contact are supported.

Load entities and constraints:

/INIGRAV

The hydrostatic pressure initialization due to gravity for fluid materials is now compatible with 2D analysis.
Any non-planar surface can be defined in the initial gravity for ALE option. This option is no longer limited to planar surfaces.

/LOAD/PBLAST

Several load blast cards can be added in the model. This development is limited to /PARITH/OFF option.

/RBODY and /RBE2

Master node of the rigid entity is automatically removed from the slave nodes list, if needed.

/RBODY

Ispher=2, Automatic correction of unphysical inertia in a rigid body. This correction ensures numerical stability. The previous method is available as Ispher=3.

/RBE3

Improvement of the Starter computation time for models with a lot of /RBE3 (> 100000).

Unit compatibility:

Local unit systems can now be set on the following /ALE/EULER entities:
- /MAT/LAW5, /MAT/LAW11, /MAT/LAW37, /MAT/LAW41, /MAT/LAW46, /MAT/LAW51, /MAT/LAW97
- /EBCS
- /DFS/LASER, /DFS/WAV_SHA
- /DFS/DETPOINT, /DFS/DETPLAN, /DFS/DETLINE, /DFS/DETCORD

/PROP/TYPE6: New flags I_tetra4 and I_tetra10 in the orthotropic solid property.
/PROP/TYPE51 and /PROP/PCOMPP: Additional materials are compatible with these composite shell properties.

User libraries:

Improvement of the user library generation when third party libraries are used
Correction of memory allocation for the user dynamic library. Some data was not correctly transferred from/to the user subroutine.
Correction of F matrix in the user material law. some values were wrong in case of large rotations.

Material, failure model, equation of states:

/EOS/NASG

An error message is now printed, if the E₀ calculated by Radioss from the user data is negative.

/MAT/LAW51

The direct input of Drücker-Prager yield criteria from Mohr-Coulomb parameters material (/MAT/LAW102) can be used in the multi-material law /MAT/LAW51 (with Iform=12).
An error message nows specifies the issue location when PSHIFT values are not identical for all sub-materials.

/MAT/LAW5

3 afterburning models (QOPT): constant burning rate from T_start to T_stop, linear burning rate from T_start to T_stop, Miller's extension and instantaneous (to retrieve 2017.0 results). This option was introduced in version 2018, but some updates have been done in order to support local units.
New bulk parameter to allow a linear EOS modeling of unreacted explosive. Default value is computed automatically. Result may change compare to previous version (usually less than 1%). Previous results may be recovered with B_unreacted=1e-20.

/MAT/LAW6

Starter will no longer output P_SH and E₀ values when it is defined in the equation of state.

/MAT/LAW12 and /MAT/LAW14

New option for plastic work reference value (W^p_ref) as in /MAT/LAW25.

/MAT/LAW24

Improvement of the estimation of the plastic strain in the concrete material /MAT/LAW24 with I_cap=2. In the previous version, the plastic strain can have negative value.

/MAT/LAW58

Automatically switch to large strain formulation (I_smstr=4) for part with fabric material. The element and material will be more stable and more accurate.

/MAT/LAW88

Improved error message when there is an input error.

/FAIL/HASHIN

New option in the failure model to propagate the failure information to the neighbor elements (flag I_frwave=2).
New option Imod to select failure according number of cycles or relaxation time.

Animation, time history and state output:

/H3D/QUAD/VORTX: Now available for material /MAT/LAW151.
/H3D/SHELL/USER/UVAR=ALL/PLY=ALL/IPT=ALL: User variables can be output for each ply in the .h3d file.
/STATE/DT/ALL: All nodes of the model, including free nodes, rigid body master node, SPH are now written in the state file. In the previous version, only the node attached to part was written.
/TH/QUAD: Strain are available for 2D solid element (/QUAD) in time history file, both for isotropic and orthotropy element properties.
/TH/BRICK and /TH/QUAD: (QVIS) time history for artificial viscosity (pseudo viscosity.
/TH/PART: Part center of gravity is now available for shell elment formulations QEPH, QBAT.

Starter and Engine output file:

Elapsed time for the Starter is printed in the Starter output file.
The cumulative time of the Starter and each Engine is written at the end of each Engine output file.
New error message when the material ID defined in the detonation card (/DFS/DET* and /DFS/WAV_SHA) is not an expected one.
The warning message #503 NODE GROUP BUILT FROM 10-NODE TETRAHEDRA is removed from the Starter output file. This message is now useless.
New timer for the ALE, EULER computation time (/MON/ON).
Correction and improvement to the Starter message #162.
Failure strain values for /FAIL/TENSTRAIN are now written in the Engine output file.

Speed and scalability:

/CONVEC and /RADIATION: Parallelization of convection and radiation option (SMP).
/INIVOL:
- Improvement of the algorithm to reduce the CPU time needed to initialize the initial volume set up (Starter).
- Improvement of the initial volume filling in order to reduce the memory used in the Starter. The issue could be seen only for big model (> 6M elements).
- Improvement of initialization of hydrostatic pressure (/INIGRAV) initialization in case of mixing between sub materials.
/ALE: Improve domain decomposition for ALE.
Algorithm improvement to reduce the memory used with the option /FRICTION in the Starter and the Engine.
Improvement of decomposition method in case the number of SPMD domains is bigger than number of deformable Lagrangian elements for model with ALE domain.
Correction of performance issue (from version 2019) for the composite material /MAT/LAW25 with failure and included in contact interface /INTER/TYPE7.
Improvement of the computation speed in case function is defined with large number of points in material law /MAT/LAW70.
Multi domain option is available for OpenMPI version.

Resolved Issues

Submodel (//SUBMODEL)

Radioss Starter no longer fails when the cards /FAIL and /VISC are defined inside a submodel (//SUBMODEL) where encrypted (/ENCRYPT or /KEY).
Imposed velocity /IMPVEL/FGEO is now compatible with submodel (//SUBMODEL). The Radioss Starter was failing in the previous versions.
The input of a local coordinate system (/SKEW) now works for /PROP/TYPE34 (SPH) when defined in a sub-model.
Contact interface /INTER/TYPE19 is now correct when used in a sub-model of a sub-model.
The Starter no longer fails when offset values defined in the //SUBMODEL are defined with parameters.

Multi-material /MAT/LAW51:

Improvement of the silent boundary (Iform=6) for the 2D analysis. The pressure was not correctly calculated.
An issue was fixed with the explosive material. Results were different between Iform=11 and Iform=12.
Correction of an issue in the inlet/outlet behavior (Iform=4 and Iform=5). Computation was failing with a specific model.
The pressure shift defined in sub-material laws is now correctly taken into account.
Time step stability improvement for a specific model to prevent a time step was reduction.

Multi fluid material /MAT/LAW151:

Correction of a potential numerical issue for material law /MAT/LAW151 with JWL sub-material and inlet /EBCS/INLET.
New error message, if EOS is missing in the multi-fluid law.
The parameter P₀ from the linear equation of state (/EOS/LINEAR) is now taken into account inside the multi-fluid law.

Other material law corrections:

/MAT/LAW71: Correction of shell stability with this material law to prevent model failure.
/MAT/LAW97 (JWLB): Numerical correction for the detonation time value.
/EOS/IDEALGAS: Unit translation correction for temperature and heat capacity.
/MATLAW58: Improvement in the stability of 4 node shell elements. The model was failing with "NaN".
/MAT/LAW88: Improvement of the unload behavior defined by a curve.
/FAIL/HASHIN: Numerical issue fixed with the different developments to improve failure and the update of the old material laws.

Contact interfaces for the manufacturing process

Draw bead normal force was applied in contact /INTER/TYPE8 (draw bead), even if the slave node is in distance more than depth + thickness.
Behavior for the thermal conducting coefficient computation according to pressure in contact /INTER/TYPE21.
Contact interface /INTER/TYPE21 behavior when using I_fric=1 and C1 coefficient.
Numerical issue when /INTER/TYPE21 and /INTER/TYPE19 are defined in the same model

Tied contact

Numerical issue when tied contact (/INTER/TYPE2) switched from kinematic to penalty formulation, if the node was a slave of several TIED contact interfaces with Spot_flag=27 or Spot_flag=28.

General contact interfaces

The friction coefficient is now always positive in contact interfaces TYPE7, 21, 24 and 25.
Computation was failing in the SPMD version when the contact interface TYPE7, 24 or 25 was activated with T_start during the second run (_0002.rad)
Improvement of the initial penetration computation in the contact interface TYPE25 with INACTI=5. Some initial forces were existing close to the edges.
Improvement of the contact interface TYPE24 in models with initial penetration and tied conditions. Some contact forces (/INTER/TYPE24) appeared between parts with tied conditions (/INTER/TYPE2).
/INTER/TYPE24: Some shell slave nodes penetrated solid master segments.
Improvement of edge2edge behavior (I_edge=1) in the contact /INTERTYPE24. Some nodes could remain anchored in a specific model.
The Starter was failing when input in contact interface /INTER/TYPE19 that used the Darmstad friction model (I_fric=2).

Shell element

The total thickness of the shell element was not correctly calculated in composites that used mixed material laws /MAT/LAW2, /MAT/LAW22, /MAT/LAW27 or /MAT/LAW32.

Solid element

Stability improvement of the solid element (HEPH) and material law /MAT/LAW38 with /PROP/SOLID, I_hkt=2. I_hkt=2 is now the default value for this material law.
Correction of a numerical issue involving HEPH solid elements and material /MAT/LAW42 where bulk scale function fct_ID_blk is used. The material behavior was not correct.
Correction of a numerical issue when the middle node of a quadratic tetrahedron element (/TETRA10) with I_tetra10=2 is defined in several tied contacts as a slave in one contact and master in the other contact. The computation was failing on some specific models.
Element stability improvement for the element switching automatically from large strain to small to prevent negative volume. This improvement concerns elements using foam or hyper-elastic materials.

Spring, truss and beam properties

Correction of numerical instability when hardening flag H=6 is used in the model.
Correction of the plastic strain on the truss elements. The plastic strain was under-estimated by a factor of 3.

Other entities improvements

ALE: Correction of the ALE force transfer through the Lagrangian surface.
/ENCRYPT: Time out feature option was not working for specific time out dates.
/INISPRI/FULL: Improved initialization (force, deformation) of the spring element /PROP/TYP13. The initialization was done correctly, but the value was released after the 1st cycle.
/*/LSENSOR: This option was not taken into account when restarting an Engine run.
/RBODY: A rigid body defined in a 2D analysis was not moving, even if the master node was not constrained.
/MONVOL/FVMBAG1: Numerical instability in the finite volume computation for a specific airbag meshed with pyramid and tetrahedron elements. The model was failing during the first cycle.
/SENSOR/SECT: Sensor behavior for signals coming from section forces FX, FY, FZ and total force in the sensor.
/XREF: Strain initialization for brick elements with small strain formulation (I_smstr=1) and material /MAT/LAW70.

Starter output file

Correction for the Property and Material parameters review. The value defined in /DEF_SOLID was not output correctly.
Correction of the property ID in the Starter error message #658.

Animation output

Numerical correction were done to the existing options /H3D/NODA/P, /H3D/NODA/TEMP and /H3D/NODA/DENS.
The output of the middle nodes of quadratic tetrahedron elements was added to the grid point stress and strain output (/H3D/NODA/GPS, /H3D/NODA/GPSTRAIN) in the H3D file format.

Single precision version

Improvements to the single precision version for solid element stability, contact interface TYPE24, contact interface TYPE2, and hyper-elastic material laws.