Home
Reference Guide
This manual provides a detailed list of all the input keywords and options available in Radioss.
LS-DYNA Input
This manual provides a list of LS-DYNA input files available in Radioss.
*CONTROL
*CONTROL_UNITS
LS-DYNA Input Interface KeywordDefines the input file unit system.

Welcome
What's New
View new features for Radioss 2025.
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 2025
  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.
- LS-DYNA Input
  This manual provides a list of LS-DYNA input files available in Radioss.
  - *AIRBAG
  - *BOUNDARY
  - *CONSTRAINED
  - *CONTACT
  - *CONTROL
    - *CONTROL_HOURGLASS
      LS-DYNA Input Interface KeywordDefine default solid and hourglass formulation for 8-node solid elements.
    - *CONTROL_OUTPUT
      LS-DYNA Input Interface KeywordDefine Starter output details.
    - *CONTROL_PARALLEL
      LS-DYNA Input Interface KeywordDefine parallel arithmetic option.
    - *CONTROL_TERMINATION
      LS-DYNA Input Interface KeywordThis keyword defines the conditions to stop a running simulation.
    - *CONTROL_TIMESTEP
      LS-DYNA Input Interface KeywordDefines time step control conditions.
    - *CONTROL_UNITS
      LS-DYNA Input Interface KeywordDefines the input file unit system.
  - *DAMPING
  - *DATABASE
  - *DEFINE
  - *ELEMENT
  - *EOS
  - *HOURGLASS
    LS-DYNA Input Interface KeywordDefine solid and hourglass formulation for 8-node solid elements.
  - *INCLUDE
  - *INITIAL
  - *INTEGRATION_SHELL
    LS-DYNA Input Interface KeywordDefine user-defined through the thickness integration rules for the composite shell element.
  - *KEYWORD
    LS-DYNA Input Interface KeywordThis keyword should always be the first card of the input file. Optionally used with *CONTROL_UNITS card to specify model units.
  - *LOAD
  - *MAT
  - *NODE
    LS-DYNA Input Interface KeywordDefines a node number and nodal coordinates in the global coordinate system.
  - *PART
    LS-DYNA Input Interface KeywordDefines a part, which combines material and property information.
  - *RIGIDWALL
  - *SECTION
  - *SET
- Multi-Domain
  This manual contains the description of the keywords for the Radioss Multi-Domain.
- Obsolete Keywords
  Keywords that are still supported, but no longer maintained (*) are considered obsolete.
- 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.

*CONTROL_UNITS

LS-DYNA Input Interface KeywordDefines the input file unit system.

It is recommended to include this keyword.

Format


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)
*CONTROL_UNITS
`Length`	`Time`	`Mass`

Definition


Field	Contents	SI Unit Example
`Length`	Unit Length: = m (Default) meters = mm millimeter = cm centimeter = inch inches (0.0254 m) = foot foot (0.3048 m) (Text)
`Time`	Unit Time: = s (Default) seconds = ms milliseconds = micro_s microseconds (Text)
`Mass`	Unit Mass: = kg (Default) kilogram = g gram = mg milligram = mtrc_ton metric ton = lb pound (0.45359237 kg) = slug pound * second² / foot (14.5939029372 kg) = slinch pound * second² / inch (175.126835244 kg) (Text)

Comments

This keyword is mapped to /BEGIN.