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Reference Guide
This manual provides a detailed list of all the input keywords and options available in Radioss.
Starter Input
This manual provides a list of all the model definition keywords and options available in Radioss.
Elements
Block Format Keyword
Springs
/SPRING
Block Format Keyword Defines a spring element. It is used for modeling connection. The spring properties are applied to the local spring coordinate system.

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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.
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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.
  - 2D and 3D Analysis Options
  - Starter Keywords Syntax
    Block Format Keyword
  - Smooth Particle Hydrodynamics (SPH)
    The Smooth Particle Hydrodynamics method formulation is used to solve the equations of mechanics, when particles are free from a meshing grid.
  - Computational Fluid Dynamics (CFD)
  - General Controls
    Block Format Keyword In this group, keywords are used to set default value, global parameter, analysis type, input/output print, damping and ALE and CFD treatment for the whole model. For default value, it is still possible to overwrite in each specific keywords.
  - Nodes
    Block Format Keyword In Radioss, two node types are available. They use Cartesian coordinate to describe the position of each node.
  - Elements
    Block Format Keyword
    - Beams and Trusses
    - Springs
      - /SPRING
        Block Format Keyword Defines a spring element. It is used for modeling connection. The spring properties are applied to the local spring coordinate system.
      - /XELEM
        Block Format Keyword Describes the multi-strand element. It could be use with /PROP/TYPE28 (NSTRAND), and it could be used for belt modelization by taking nodes upon the dummy.
    - Shells
    - Solids
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  - Component and Parts Organization
    Block Format Keyword In this group, keywords are used to combine material and property information (/PART), assemble model (/SUBSET) or define a separate model (//SUBMODEL).
  - Interfaces
    Block Format Keyword Interfaces solve the contact and impact conditions between two parts of a model. Several interface types are available in Radioss and use different contact treatments.
  - Materials
  - Properties
    Block Format Keyword
  - Monitored Volumes (Airbags)
    Block Format Keyword Monitored volumes can be used to model an airbag, tire, tank, or any closed volume.
  - Constraints
    Block Format Keyword Radioss supports several different kinematic constraints, which are mainly used to impose acceleration, velocity, displacement or temperature in structure or constraint the moving of structure. They are mutually exclusive for each degree-of-freedom (DOF). Two kinematic conditions applied to the same node may be incompatible.
  - Load Cases
    Block Format Keyword In Radioss the following load cases are available. Stress/strain as initial state could be considered by modeling, as well as pressure, gravity, and thermal load.
  - Tools
    Block Format Keyword In this group, tools like transformation, frames, skews, and curve are introduced.
  - Groups(Sets)
    Block Format Keyword Keywords in this group are used to define how to select a group of node, part, elements, lines, or surfaces.
  - Adaptive Meshings
    Block Format Keyword Adaptive Meshing is used in metal forming to divide the element to better describe the geometry. /ADMESH/GLOBAL and /ADMESH/SET are not available for SPMD computation.
  - Output Database
    Block Format Keyword Time histories output for different element groups, section output, or gauge output are described in this group.
  - Obsolete
    Block Format Keyword Keywords that are still supported, but no longer maintained (*) are considered obsolete.
- 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.
- 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.

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/SPRING

Block Format Keyword Defines a spring element. It is used for modeling connection. The spring properties are applied to the local spring coordinate system.

Format


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/SPRING/`part_ID`
`sprg_ID`	`node_ID`₁	`node_ID`₂	`node_ID`₃	`node_ID`₄	`node_ID`₅	`node_ID`₆			`Skew_ID`

Definition


Field	Contents	SI Unit Example
`part_ID`	Part identifier of the block. (Integer, maximum 10 digits)
`sprg_ID`	Element identifier. (Integer)
`node_ID`₁	Node identifier 1 for spring. (Integer)
`node_ID`₂	Node identifier 2 for spring. (Integer)
`node_ID`₃	Node identifier 3. (Integer)
`node_ID`₄	Node identifier 4. (Integer)
`node_ID`₅	Node identifier 5. (Integer)
`node_ID`₆	Node identifier 6. (Integer)
`Skew_ID`	Optional: Skew system identifier. Only used when the spring is defined using /PROP/TYPE8 (SPR_GENE) or /PROP/SPR_MAT (TYPE23) with /MAT/LAW108 (SPR_GEN). 8 (Integer)

Comments

The identifier must be unique in each element family, but it is advised for each element type to have a unique element identifier in the global model.
More than one spring block can be used to define a part.
Any number of springs can be defined in one block.
Spring elements with /PROP/TYPE8 (SPR_GENE) or /PROP/TYPE23 (SPR_MAT) with /MAT/LAW108 (SPR_GENE) may have a length equal to 0.
Spring elements with /PROP/TYPE12 (SPR_PUL), /PROP/TYPE13 (SPR_BEAM), /PROP/TYPE23 (SPR_MAT) and /PROP/TYPE13 (SPR_BEAM) with /MAT/LAW113 (SPR_BEAM) should have a non-zero length.
Spring element is defined with two nodes: node_ID₁ and node_ID₂.
The plane XY is defined with the three nodes (node_ID₁, node_ID₂, and node_ID₃); the third node, node_ID₃ defines the Y direction also for the non-symmetric spring (/PROP/TYPE13 or /MAT/LAW113).
Figure 1.
Both node_ID₅ and node_ID₆ are reserved for future use for new joints types.
For spring elements using /PROP/TYPE8 (SPR_GENE) or /PROP/SPR_MAT with /MAT/LAW108, the local system can be defined for each element using /SPRING Skew_ID. If Skew_ID is not defined for each element, the local system defined in /PROP/TYPE8 (SPR_GENE) or /PROP/TYPE23 (SPR_MAT) Skew_ID is used. If a system is not defined in the element or property, then the global system is used.