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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.
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).
/SUBSET
Block Format Keyword Describes the subsets.

Welcome
What's New
View new features for Radioss 2024.1.
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.
  - 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
  - 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).
    - /PART
      Block Format Keyword Defines a part, which combines material and property information. Optionally, the interface gap can be specified.
    - /SUBSET
      Block Format Keyword Describes the subsets.
    - //SUBMODEL
      Block Format Keyword The submodel card defines a part of the model with separate definition of numeration, unit system and Radioss version.
  - 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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/SUBSET

Block Format Keyword Describes the subsets.

Format


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/SUBSET/`subset_ID`
`subset_title`
`sub_ID1`	`sub_ID2`	`sub_ID3`	`sub_ID4`	`sub_ID5`	`sub_ID6`	`sub_ID7`	`sub_ID8`	`sub_ID9`	`sub_ID10`

Definition


Field	Contents	SI Unit Examples
`subset_ID`	Subset identifier. (Integer, maximum 10 digits)
`subset_title`	Subset title. (Character, maximum 100 characters)
`sub_ID1`, `sub_ID2`, … `sub_ID10`	Children subset identifiers. (Integer)

Part Definition

/PART/1000
extra part
200 100
/PART/1001
roof part
100 100 1
/PART/1002
door part 1
100 101 12
/PART/1003
door part 2
100 102 12
/PART/1004
head part 1
200 200 21
/PART/1005
head part 2
201 200 21
/PART/1006
legs part 1
201 200 22

Subset Definition

/SUBSET/1
car
12
/SUBSET/12
door
/SUBSET/21
head
/SUBSET/22
legs
/SUBSET/2
dummy
21 22

Comments

A subset is a non-homogeneous element assembly.
A subset contains a set of parts and (or) a set of subsets. Subsets can be structured to generate a hierarchical model.
The subset to which a part belongs is defined in the /PART option.
The subsets belonging to one subset are defined with the /SUBSET option.
Each subset ID referenced by /PART option or by /SUBSET option has to be defined with a /SUBSET option. The same subset_ID can only be referenced once for all /SUBSET options.
Subsets not referenced in any /SUBSET option list are children of the global model subset.
The main difference between a subset and an element group (/GRSHEL, /GRBRIC, ...) is that a subset hierarchy defines a complete non-redundant model organization. Elements groups only cover one part of the model, and some elements can belong to several groups.
The number of levels in a hierarchical organization is not limited.
Figure 1. Hierarchical Model