Altair Radioss 2021 Release Notes

New Features

New input file reader
  • The new reader is based on the same configuration files used in HyperWorks. This allows faster and better support of all new Radioss features in HyperWorks.
  • This new reader solves several issues involving unit system conversion and improved support of entities in submodels.
  • Models created in the version 4 format or earlier cannot be read by the new Radioss input file reader. These files can be updated to a newer input format version using HyperMesh or HyperCrash.
New general set option
  • New general set (/SET/GENERAL) where any nodes, elements, parts, subsets, boxes, or sets can be added or removed. Options exist to include external or all surfaces.
  • This new set can be used with any entity to define a node group, surface, or element group.
  • When a set is referenced by a keyword, the entities referenced (nodes, surface, line, or elements) are automatically extracted from the set.
New reader for LS-DYNA input format (Beta version)
  • A model in the LS-DYNA input format can be used as input for a Radioss computation (Starter and Engine).
  • The LS-DYNA model is read and mapped to equivalent Radioss functionality.
  • The number of features and parameters currently supported are detailed in the Reference Guide > LS-DYNA Input.
  • Due to the large number of new input options, this first release of the reader is a beta version.
ALE grid control (/ALE/GRID/*)
  • New grid control /ALE/GRID/LAPLACIAN based on Laplacian smoothing method.
  • New grid control /ALE/GRID/VOLUME based on volume. Each ALE node position is computed as the average position of the centroids of the elements to which it is connected. The volume of the elements is used to weight the average positions.
Boundary conditions
  • New cyclic boundary option /BCS/CYCLIC to model a section of a rotary machine, such as a turbine engine. The cyclic boundary is applied on each face of the cyclic section. This option is used with static conditions where the equivalent centrifugal force is applied with a specific load (/LOAD/CENTRI).
Element and property
  • For solid and thick shell properties, the flags Istrain and Ihkt are now automatically defined so they have been removed from the input deck. The flags Ismstr, Icpre, and Iframe can be automatically defined by Radioss based on the element type and material by using the new input value -1 in the property or -2 in /DEF_SOLID.
  • Elastic-plastic material /MAT/LAW44 can be assigned to beam element /PROP/TYPE3, /PROP/TYPE18 and truss element /PROP/TRUSS.
Materials and failure models
  • New failure model based on Mullins Ogden-Roxburgh model (/FAIL/ MULLINS_OR) compatible with /MAT/LAW92, /MAT/LAW95, and /MAT/LAW100. This failure model simulates viscous elastic behavior with stress reduction.
  • New elastic-plastic material law for high tensile strength steel and damage model (/MAT/LAW104) with non-local regularization method (/FAIL/GURSON).
  • New elastic-viscous-plastic model for polymer materials (/MAT/LAW101).
Result output
  • New plastic strain output results for any integrations point of the integrated beam element (/PROP/TYPE18) in the animation files (/ANIM/BEAM/EPSP) and H3D files (/H3D/BEAM/EPSP).
  • New engineering total strain tensor output for shell and solid elements in .h3d file (/H3D/SHELL/TENS/STRAIN_ENG, /H3D/SOLID/TENS/STRAIN_ENG).
  • New output stress or strain tensor on the external skin of the solid part in .h3d file (/H3D/SOLID/TENS/STRESS/OUTER, /H3D/SOLID/TENS/STRAIN/OUTER). An external skin is automatically created by Radioss to display the results. This output is useful to post-process Forming Limit Diagrams during the stamping process.
  • FLD damage factor indicator and FLD failure zone factor are extended to the outer surface of the thick shell and solid element in the .h3d file (/H3D/SOLID/FLDZ/OUTER, /H3D/SOLID/FLDF/OUTER).
Altair Compute Console
  • The HyperWorks Run Manager was replaced with an updated utility named Altair Compute Console (ACC).
  • Radioss can now be started by using the Compute Console shortcut in the menu which replaces the previous Radioss shortcut.
  • The Compute Console is the easiest way to launch Radioss on a local host or submit a simple job to a remote Linux server/cluster or PBS system.
ARM processor
  • Radioss is now available on ARM64 machines using the Linux operating system.


  • New airbag input card /MONVOL/FVMBAG2 with the same advanced features as /MONVOL/FVMBAG1 and a simpler input.
  • The finite volume is meshed using HyperMesh tetrahedron mesher when using kmesh = 12 or kmesh = 14 for the FVM bags in /MONVOL/FVMBAG1.
  • A new option in /MONVOL/PRES to input the pressure is a function of the relative volume (V/V0) with the flag Itypfun = 2 and a function of time multiplied by relative volume (V0/V) with Itypfun = 3.
ALE options
  • Improvement of the ALE grid formulations (/ALE/GRID/*) with linear tetrahedron element (/TETRA4).
  • Volume fractions can be initialized with 1D initial mapping /INIMAP1D and with 2D initial mapping /INIMAP2D.
  • Unit system compatibility is added for the boundary material /MAT/LAW11.
Contact interface
  • Improvement of computation stability for models with Advanced Mass Scaling (/AMS) and tied contact (/INTER/TYPE2) with Spotflag=27.
  • A new feature for the thermal conduction and radiation in the contact interface for forming application (/INTER/TYPE21). The thermal conduction continues with a user-defined decay factor when there is no more contact and within a user-defined distance.
  • New contact stiffness options, Isft=12, 13, 14 for the contact force resolution based on the Nitsche’s method in contact interface /INTER/TYPE24. This method uses the element stress state to adjust the contact stiffness.
  • Edge to Edge contact was added in the contact interface /INTER/TYPE25. The friction is not yet available for the edge to edge contact.
  • New option Itied in contact interface /INTER/TYPE7 to tie a secondary node when its time step becomes smaller than a defined time step value (dtmin). This option helps reduce the mass increase during a computation.
Element and property
  • A local coordinate system can be defined in the spring element (/SPRING). This option can be used for general spring (/PROP/TYPE23 and /MAT/LAW108).
Material and failure models
  • Reduction of the memory used for the user variables in the material laws. The restart file size is also reduced.
  • Correction of spring element behavior for Iequil=1 for the spring material /MAT/LAW108.
  • Correction of time history output concerning Inertia, kinetic energy, and CoG of spring elements with spring material /MAT/LAW108.
  • For better computation stability especially when using the single-precision version, the maximum default values are changed from 1030 to 1020 in several material laws. This change should not affect the results of the current models. The input is updated automatically when values larger than 1020 are set in the model.
  • The yield surface can be defined using a /FUNCT in material /MAT/LAW44 resulting in different behavior in combination with the definition of the analytical yield VP.
  • New error message when the void volume fraction does not respect the following rule: fI < fc < fF in the Gurson material /MAT/LAW52.
  • Starter improvement to display warning and message when functions or parameters are missing in the fabric material /MAT/LAW58.
  • New yield surface option with Barlat 3 parameter plane stress in the Yoshida material /MAT/LAW78.
  • Phase transformation is now available during the heating process in the material /MATLAW80.
  • New option to define the elastic shear modulus G in the connection material /MAT/LAW83, independently from the elastic Young's modulus.
Starter messages
  • New Starter error message when the /SHELL element is used in a 2D analysis (N2D3D=1,2), instead of /QUAD.
  • New Starter error message when the /SH3N element is used in a 2D analysis (N2D3D=1,2), instead of /TRIA.
  • New test to check to ensure that enough memory is available before starting the computation using the /BEM/DAA feature.
  • A warning message is displayed when a /HEAT/MAT card is used with an Eulerian or ALE material with the Iform=1 Lagrangian formulation. The flag is automatically switched to 0 ALE formulation.
  • A warning message is displayed when /INITEMP or /IMPTEMP are used, and ALE or EULER materials are present in the model.
  • A new error message is output when the /THERM_STRESS option is used with an ALE or EULER material.
  • New error message when an element defined in a model refers to a part (/PART) that does not exist in the model.
  • New warning message when the section force /SECT with cut methodology is defined in a submodel //SUBMODEL with offset. The offset is not applied when reading the SC01 file.
Result output
  • Schlieren now output with 2D and staggered scheme using /H3D/ELEM/SCHLIEREN or /ANIM/ELEM/SCHLIEREN.
  • The contact energy is output as elastic contact energy, frictional energy, and damping energy (for some contacts) to both the /TH/INTER and global variables when the Engine option /TH/VERS = 2021 is defined.
  • Correction of the time history output for subset and parts for the outputs, center of gravity, momentum, and inertia (/TH/PART and (/TH/SUBS).
  • The center of gravity of an SPH PART is now output in the time history file (/TH/PART).
  • The generalized stress variable F1, F2, F12, Q1, and Q2 for shell elements are renamed as "STRESS", instead of "FORCE" (/TH/SHELL).
Other enhancements
  • /FRAME/FIX now supports a local unit system.
  • Simplification of the /GRAV input. By default, gravity is applied to all nodes using a constant value defined using the scale factor flag.
  • Performance optimization of time history output (TH file).
  • Improvement of the unit management with single precision. The Starter was failing with for ID greater than 8 million.

Resolved Issues

  • Improvement of the submodel (//SUBMODEL) compatibility for the airbag /MONVOL/AIRBAG1.
ALE options
  • Correction of various issues for the detonator’s options (/DFS/DET*).
  • Improvement of result mapping from 2D to 3D model for materials with an explosive.
  • Correction of unit conversion issue for the initial velocity option (/INIVEL/GRID, /INIVEL/T+G).
  • Improvement of the fluid and structure coupling with contact interface /INTER/TYPE18 and with multi-fluid material /MAT/LAW151.
  • Starter issue correction when /EULER/MAT is used on sub-material of material /MAT/LAW151.
  • Improvement for the handling of pressure shift option (Psh) with material /MAT/LAW151 with Iform=12. A new warning message is displayed when the pressure shift value is different in the sub-materials.
Boundary conditions
  • Correction and update of the boundary condition (/BCS/LAGMUL) and rigid body (/RBODY/LAGMUL) with the Lagrangian method. The behavior was not correct.
  • Correction of the rigid body (/RBODY) behavior in the Radioss SPMD version when /FUNCT_SMOOTH used with imposed displacement is defined on the main node.
Contact interface
  • The tied contact (/INTER/TYPE2, Spotflag=27,28) will switch automatically to penalty formulation when a secondary node is defined in /IMPDISP, /IMPVEL, /IMPACC or constrained with cut approach (/SECTION with Isva=100,101).
  • Improvement of the model stability with SPMD and the thermal option Ithe=2 with contact /INTER/TYPE21. A specific model was failing.
  • Correction of a numerical issue in the interface /INTER/TYPE21 and thermal conduction option in the HMPP parallel version.
Imposed conditions / loadcase
  • Correction of the centrifugal load (/LOAD/CENTRI) applied on a structure using a non-constant rotational velocity and local coordinate system.
  • The heat transfer coefficient in /CONVEC was not converted into the right working unit system.
  • The option /IMPDISP/FGEO is now compatible with submodel (//SUBMODEL).
  • Several corrections to the /IMPFLUX option for unit system conversion and submodel compatibility.
  • Several corrections on the /LOAD/PFLUID option for unit system conversion and submodel compatibility.
  • Improvement of the bolt preloading (/PRELOAD) behavior for large global rotations. The preloading force was not constant. There are still some issues with this option with the single-precision version.
Element property
  • The unit of DTmin was not correctly defined and initialized in the orthotropic thick shell property (/PROP/TYPE21).
  • The numerical damping parameter dn was not used for the QBAT and DKT18 shell formulations in /PROP/SHELL.
  • Correction of the kinetic energy output for a solid part with /TETRA10 elements and the formulation Itetra10=2.
  • The middle node of the quadratic tetrahedron element (/TETRA10) with the formulation Itetra10=2 can be defined in an RBE2 element (partial dof).
  • Correction of an instability issue of 3 node shell element /SH3N with the option Ish3n < 4 and Idrill=1 in /PROP/SHELL.
  • Correction of numerical error of solid elements (/PROP/SOLID) with Ismstr=10 and elastic material /MAT/LAW1.
  • Modification of the Navier-Stokes viscosity behavior in solid properties /PROP/TYPE14 and /PROP/TYPE6. The behavior has been changed to better compute the critical damping. Also, the time step computation has been updated.
  • Correction of unit conversion for the axisymmetric spring property (/PROP/TYPE25).
  • The curve abscissa scale factor Lscale was not used for the unit conversion in the spring property /PROP/TYPE26.
  • Loading and unloading functions defined in the spring property /PROP/TYPE26 were not correctly reported in the Starter output file.
  • The parameter h was not correctly taken into account, if the SPH property (/PROP/SPH) was defined in a //SUBMODEL.
  • Improvement of the shell behavior with the composite property /PROP/TYPE51 when the material assigned in the part is different than the one used in the plies. The computation was failing or was giving wrong results.
  • Membrane damping dm defined in shell property (/PROPERTY/TYPE51) was not taken into account for material /MAT/LAW25. This modification may lead to some differences in the results.
Materials and failure models
  • Correction of the flag Ifail_so=1 in the failure model /FAIL/SNCONNECT. The solid element was failing only when all integration points reach the failure limit.
  • Correction of the failure model /FAIL/BIQUAD for solid elements. The issue may cause too early failure in the tension load.
  • Improvement of the material behavior /MAT/LAW36 with VP=1. It was causing non-smooth thickness distribution at the end of a blow molding simulation.
  • Correction of the strain rate calculation for /MAT/LAW36 applied to beam elements /PROP/TYPE18.
  • Correction of the unit translation of parameter Einf in /MAT/LAW43.
  • The numerical damping parameter dn defined in the shell property was not taken into account for material /MAT/LAW58.
  • Material stability improvements for /MAT/LAW65 with specific parameters and loading conditions.
  • Correction of the pressure computation when plastic behavior is reached in material /MAT/LAW72 for solid elements. The computation may become unstable.
  • Correction of numerical instability for specific hot forming application in the material /MAT/LAW80. The shell element was diverging.
  • Material stability improvement for /MAT/LAW87.
  • Improvement of the dynamic behavior for elastic vibrations during the unloading phase or quasi-static loading phase in material /MAT/LAW90.
  • Improvement of the material /MAT/LAW94 for quadratic tetrahedron (/TETRA10) elements.
Result output
  • Correction of the strain tensor output per integration points for the solid element. The shear strain component was 2 times too high.
  • Improvement of the ply angle display when the initial orientation is 0°. The same as elementary material reference orientation. The ply angle was randomly displayed as +/- 180° with the output (/ANIM/SHELL/PHI or /H3D/SHELL/PHI).
  • The native .h3d file was corrupted and not readable when a subset (/SUBSET) did not have any title or was a blank line. A default title is automatically added to the subset card.
  • Correction of a numerical issue when NPT=ALL was requested on a model defined with composite shell properties (/H3D/SHELL/*). The keyword was rejected by the Engine.
  • Improvement of the stress and strain tensors output for the composite thick shell property (/PROP/TYPE22), both for animation and H3D files.
  • Correction of the time history output for the part and subset of quadratic tetrahedron elements (/TETRA10). The inertia and COG position was wrong in the part output (/TH/PART).
Other corrections
  • The checkpoint restart option can now be used with quadratic tetrahedron elements /TETRA10 with Itetra10=2
  • A specific model with rivets (/RIVET) set in time history (/TH) was failing with the SPMD version.
  • Multi-domain is now handling correctly /GAUGE and /ACCEL when present in the same input deck.
  • Correction of several issues in the sensors (/SENSORS) for the Radioss HMPP version. The results could be wrong depending on the model decomposition.
  • Correction of a possible error or core dump of Radioss Starter with the ellipsoid surface (/SURF/ELLIPS).
  • Improvement of the cumulative computation time written in the Engine output file for the single precision version in a multiple Engine run. The computation time values were not correctly reported from 1 run to the next one.