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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.
*ELEMENT
*ELEMENT_SEATBELT_RETRACTOR
LS-DYNA Input Interface KeywordDefines a 1D seat belt retractor element.

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Radioss^® is a leading explicit finite element solver for crash and impact simulation.
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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
  - *DAMPING
  - *DATABASE
  - *DEFINE
  - *ELEMENT
    - *ELEMENT_BEAM
      LS-DYNA Input Interface KeywordDefines a beam, discrete beam, or a truss element.
    - *ELEMENT_DISCRETE
      LS-DYNA Input Interface KeywordDefines a 1 degree of freedom spring element.
    - *ELEMENT_MASS
      LS-DYNA Input Interface KeywordThis keyword defines mass added to nodes or node sets.
    - *ELEMENT_MASS_PART
      LS-DYNA Input Interface KeywordThis keyword defines mass added to parts or part sets.
    - *ELEMENT_PLOTEL
      LS-DYNA Input Interface KeywordDefines a spring element without any stiffness for visualization.
    - *ELEMENT_SEATBELT
      LS-DYNA Input Interface KeywordDefines a 1D seat belt element.
    - *ELEMENT_SEATBELT_ACCELEROMETER
      LS-DYNA Input Interface KeywordThis keyword defines an accelerometer.
    - *ELEMENT_SEATBELT_PRETENSIONER
      LS-DYNA Input Interface KeywordDefines a 1D seat belt pretensioner element.
    - *ELEMENT_SEATBELT_RETRACTOR
      LS-DYNA Input Interface KeywordDefines a 1D seat belt retractor element.
    - *ELEMENT_SEATBELT_SENSOR
      LS-DYNA Input Interface KeywordDefines a seat belt sensor.
    - *ELEMENT_SEATBELT_SLIPRING
      LS-DYNA Input Interface KeywordDefines a 1D or 2D seat belt slipring.
    - *ELEMENT_SHELL
      LS-DYNA Input Interface KeywordDefines a shell element with 3 or 4 nodes.
    - *ELEMENT_SOLID
      LS-DYNA Input Interface KeywordDefines 3-dimensional solid elements.
    - *ELEMENT_SPH
      LS-DYNA Input Interface KeywordDefines a Smooth Particle Hydrodynamic (SPH).
    - *ELEMENT_TSHELL
      LS-DYNA Input Interface KeywordDefines 3-dimensional thick shell elements.
  - *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
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Verification Problems
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Frequently Asked Questions
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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.

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*ELEMENT_SEATBELT_RETRACTOR

LS-DYNA Input Interface KeywordDefines a 1D seat belt retractor element.

Format


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)
*ELEMENT_SEATBELT_RETRACTOR
`RID`	`RNID`	`REID`	`SENS_ID1`	`SENS_ID2`	`SENS_ID3`	`SENS_ID4`
`T`_delay	`PULL`	`FCT_L`	`FCT_UL`	`FEED`

Definition


Field	Contents	SI Unit Example
`RID`	Retractor identifier. (Integer)
`RNID`	Retractor node identifier. (Integer)
`REID`	Seat belt element identifier attached to the retractor. (Integer)
`SENS_ID1`	Sensor for retractor activation. (Integer)
`SENS_ID2`	Sensor for retractor activation. (Integer)
`SENS_ID3`	Sensor for retractor activation. (Integer)
`SENS_ID4`	Sensor for retractor activation. (Integer)
`T`_delay	Time delay. (Real)	$[s]$
`PULL`	Seat belt pull length for locking. (Real)	$[m]$
`FCT_L`	Load curve identifier. (Integer)
`FCT_UL`	Unload curve identifier. (Integer)
`FEED`	Feed element length. (Real)	$[m]$

Comments

This keyword maps to /RETRACTOR/SPRING.
First non-zero sensor is used to activate pretensioner. Time delay T_delay is added to the sensor activation.