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Radioss 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.
*CONTACT
*CONTACT_AUTOMATIC_BEAMS_TO_SURFACE
LS-DYNA Input Interface KeywordDefine nodes of beam elements to surface contact interface.

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Radioss is a leading explicit finite element solver for crash and impact simulation.
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Radioss User Guide
This manual provides details on the features, functionality, and simulation methods available in Altair Radioss.
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 2026
  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
    - *CONTACT_AIRBAG_SINGLE_SURFACE
      LS-DYNA Input Interface KeywordDefine automatic single contact for airbags.
    - *CONTACT_AUTOMATIC_BEAMS_TO_SURFACE
      LS-DYNA Input Interface KeywordDefine nodes of beam elements to surface contact interface.
    - *CONTACT_AUTOMATIC_GENERAL
      LS-DYNA Input Interface KeywordDefine an automatic general contact interface between elements.
    - *CONTACT_AUTOMATIC_NODES_TO_SURFACE
      LS-DYNA Input Interface KeywordDefine nodes to surface contact interface.
    - *CONTACT_AUTOMATIC_ONE_WAY_SURFACE_TO_SURFACE
      LS-DYNA Input Interface KeywordDefine surface to surface contact between a set of shell and solid elements.
    - *CONTACT_AUTOMATIC_SINGLE_SURFACE
      LS-DYNA Input Interface KeywordDefine automatic single contact interface between elements.
    - *CONTACT_AUTOMATIC_SURFACE_TO_SURFACE
      LS-DYNA Input Interface KeywordDefine surface to surface contact between a set of shell and solid elements.
    - *CONTACT_ERODING_NODES_TO_SURFACE
      LS-DYNA Input Interface KeywordDefine nodes to surface contact interface.
    - *CONTACT_ERODING_SINGLE_SURFACE
      LS-DYNA Input Interface KeywordDefine automatic single contact interface set of shell and solid elements.
    - *CONTACT_ERODING_SURFACE_TO_SURFACE
      LS-DYNA Input Interface KeywordDefine surface to surface contact between a set of shell and solid elements.
    - *CONTACT_FORCE_TRANSDUCER_PENALTY
      LS-DYNA Input Interface KeywordAccumulates output for contact forces (from other existing contacts) acting on a given set of nodes/segments determined by set, part or subset with optional selection of interacting main side contact entities and intersection between sets and boxes.
    - *CONTACT_INTERIOR
      LS-DYNA Input Interface KeywordDefine an interior contact for each part defined in the defined set of parts.
    - *CONTACT_NODES_TO_SURFACE
      LS-DYNA Input Interface KeywordDefine nodes to surface contact interface.
    - *CONTACT_SPOTWELD
      LS-DYNA Input Interface KeywordDefine nodes to surface contact interface dedicated for spotweld connection.
    - *CONTACT_TIEBREAK
      LS-DYNA Input Interface KeywordDefines tied contact between entities without failure.
    - *CONTACT_TIED
      LS-DYNA Input Interface KeywordDefines tied contact between entities.
  - *CONTROL
  - *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.
  - *INTERFACE_SPRINGBACK
    LS-DYNA Input Interface KeywordDescribes the variables to output in an initial state file or DYNAIN file at the end of the analysis.
  - *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
Radioss Example Guide
This manual presents examples solved using Radioss with regard to common problem types.
Radioss Verification Problems
This manual presents solved verification models.
Radioss Frequently Asked Questions
This section provides quick responses to typical and frequently asked questions regarding Radioss.
Radioss Theory Manual
This manual provides detailed information about the theory used in the Altair Radioss Solver.
Radioss User Subroutines
This manual describes the interface between Altair Radioss and user subroutines.

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*CONTACT_AUTOMATIC_BEAMS_TO_SURFACE

LS-DYNA Input Interface KeywordDefine nodes of beam elements to surface contact interface.

Format


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)
*CONTACT_AUTOMATIC_BEAMS_TO_SURFACE_`{OPTION3}`

If OPTION3 = ID, insert the following line


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)
`inter_ID`	`Title`


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)
`SSID`	`MSID`	`SSTYP`	`MSTYP`
`FS`	`FD`	`DC`				`Tstart`	`Tstop`
`SFS`	`SFM`	`SST`	`MST`	`SFTS`	`SFMT`	`FSF`

Optional Card A


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)
`SOFT`

Optional Card B


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)

Optional Card C


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)
			`DTSTIF`

Definition


Field	Contents	SI Unit Example
`OPTION3`	ID Include a contact identifier and title
`inter_ID`	Contact interface identifier. (Integer)
`Title`	Contact interface title. (Character, maximum 70 characters)
`SSID`	Secondary set or part identifier. (Integer)
`MSID`	Main set or part identifier. (Integer)
`SSTYP`	Input secondary set type. = 2 Part set ID = 3 Part ID (Integer)
`MSTYP`	Input main set type. = 0 Segment set ID = 1 Shell element set ID = 2 Part set ID = 3 Part ID = 5 All parts (`SSID` is ignored) = 6 Part set ID. All parts are included in the contact except the one defined in the part set ID = 7 Subset set ID (Integer)
`FS`	Static friction coefficient. (Real)
`FD`	Dynamic friction coefficient. (Real)
`DC`	Exponential decay coefficient. (Real)	$[\frac{s}{m}]$
`Tstart`	Start time. (Real)	$[s]$
`Tstop`	Stop time. Default = 1E+30 (Real)	$[s]$
`SFS`	Secondary stiffness scale factor. (Real)
`SFM`	Main stiffness scale factor. (Real)
`SST`	Secondary maximum gap value. (Real)	$[m]$
`MST`	Main maximum gap value. (Real)	$[m]$
`SFTS`	Secondary contact gap scale. (Real)
`SFMT`	Main contact gap scale. (Real)
`FSF`	Coulomb friction coefficient scale factor. (Real)
`SOFT`	Contact stiffness definition flag. = 0 Contact stiffness is the average of the main and secondary stiffness. = 1 Contact stiffness is the minimum of the main and secondary stiffness. = 2 Contact stiffness based on the average of the main and secondary stiffness and time step stability condition. (Integer)
`DTSTIF`	Time step used for stiffness calculation. Used only if `SOFT` > 0. (Real)

Comments

This keyword maps to /INTER/TYPE25.