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Reference Guide
This manual provides a detailed list of all the input keywords and options available in Radioss.
Engine Input
This manual provides a list of all the solution definition keywords and options available in Radioss.
General Controls
Engine Keyword In this group keywords are used to generally define the output style, control of computation, damping and ALE setup during the computation.
Computation
/RUN
Engine Keyword Identifies the run number.

Welcome
What's New
View new features for Radioss 2024.
Overview
Radioss^® is a leading explicit finite element solver for crash and impact simulation.
Tutorials
Discover Radioss functionality with interactive tutorials.
User Guide
This manual provides details on the features, functionality, and simulation methods available in Altair Radioss.
Reference Guide
This manual provides a detailed list of all the input keywords and options available in Radioss.
- File Extensions and Formats
  Current Radioss format uses the 12x extension format.
- Single File Input
  This format allows running either Starter or Engine with the same file.
- New Keywords in 2024
  New and modified features in Radioss.
- Starter Input
  This manual provides a list of all the model definition keywords and options available in Radioss.
- Engine Input
  This manual provides a list of all the solution definition keywords and options available in Radioss.
  - Engine Keywords Syntax
  - General Controls
    Engine Keyword In this group keywords are used to generally define the output style, control of computation, damping and ALE setup during the computation.
    - Formats
    - Computation
      - /KILL
        Engine Keyword The Engine is stopped and restart files are not created, if one of the following criteria is exceeded.
      - /MADYMO
        Engine Keyword Activates MADYMO- Radioss coupling.
      - /MASS/RESET
        Engine Keyword Reset the mass of the model to the initial mass computed at t=0.
      - /MON
        Engine Keyword Provides an estimation of the CPU time spent for each processor.
      - /NEGVOL
        Engine Keyword Solid element control for elements with negative volumes. Switch to small strain formulation or stop the run a solid elements volume becomes negative.
      - /PARITH
        Engine Keyword Turns the parallel arithmetic ON/OFF.
      - /RAD2RAD/ON
        Engine Keyword To activate Multi-Domain coupling, Radioss Engine Input file must contain the following directive.
      - /RERUN
        Engine Keyword Permits to continue a previous Radioss run.
      - /RUN
        Engine Keyword Identifies the run number.
      - /SENS/RESET
        Engine Keyword Option to reset the sensor status at the beginning of the run.
      - /STOP
        Engine Keyword The Engine is stopped, due to reached energy error ratio criteria, total mass ratio criteria or nodal mass ratio criteria.
      - /STOP/LSENSOR
        Engine Keyword The Engine is stopped due to sensor activation, when the first sensor in the defined list is activated.
      - /THERMAL
        Engine Keyword Thermal analysis.
    - Input/Output
    - Damping
    - ALE
  - Deletion/Input Modifications
    Engine Keyword In this group, keywords are used for modification (deletion or add options) in Engine.
  - Animation and Post-processing Output Files
    Generates animation files containing results according to the keywords specified. The keywords are specified in the topics within Animation and Post-processing Output Files.
  - Implicit Solution
    Engine Keyword In this group keywords are used for implicit solution. Different implicit solver methods (linear, nonlinear, buckling or quasi-static), different options to control the implicit computation, different implicit time step method and implicit output messages are introduced.
  - Kinematics and Loading
    Engine Keyword In this group, keywords are used to define the kinematic condition (constrain/release rotation or translation DOF) and initial condition (rotational/translational velocity).
  - Time Step
    Engine Keyword In this group, keywords are used to define different time step control (STOP, KILL, CST or DEL, and so on) for different entities (shell, brick, beam, airbag, interface, and so on) during the computation.
  - Initial State
    Engine Keyword In this group, keywords are used to output different info (like stress, strain, orthotropy direction, temperature, and so on) in a state file (STA-File).
  - Obsolete
    Engine Keyword Keywords that are still supported, but no longer maintained (*) are considered obsolete.
- LS-DYNA Input
  This manual provides a list of LS-DYNA input files available in Radioss.
- Optimization Keywords
  Optimization Keyword This manual contains the description of the keywords for the Radioss optimization. This manual is compatible with the version 2018 of Radioss.
- Multi-Domain
  This manual contains the description of the keywords for the Radioss Multi-Domain.
- Other Files
- Definition
Example Guide
This manual presents examples solved using Radioss with regard to common problem types.
Verification Problems
This manual presents solved verification models.
Frequently Asked Questions
This section provides quick responses to typical and frequently asked questions regarding Radioss.
Theory Manual
This manual provides detailed information about the theory used in the Altair Radioss Solver.
User Subroutines
This manual describes the interface between Altair Radioss and user subroutines.

/RUN

Engine Keyword Identifies the run number.

Format

/RUN/Run Name/Run Number/Restart Letter

T_stop

Definition


Field	Contents	SI Unit Example
`Run Name`	Character variable that identifies the problem solved. (Character, minimum 4; maximum 80 characters)
`Run Number`	The run numbers 1, 2, ... (Integer)
`Restart Letter`	(Optional) Restart file identifier = I, J, K If several restarts were saved in the previous run.
`T`_stop	Final time for the run.

Comments

If using MADYMO- Radioss coupling, the final run time taken into account is not T_stop, but the final time defined in MADYMO input.
Restart letter could be I, J, K, ...

= J

Run Restart with Runname_0001_J.rst

= K

Run Restart with Runname_0001_K.rst

These Restart files are saved in previous run by using /RFILE.