Home
Reference Guide
This manual provides a detailed list of all the input keywords and options available in Radioss.
Other Files
Flexible Body Input File
Create Flexible Body Input File with Radioss
/EIG in Radioss Starter is used to define the part of the model to be included in the flexible body, the type and number of modes to be computed.

Welcome
What's New
View new features for Radioss 2024.
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.
- 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
  - .h3d Output File
    The .h3d file is a compressed binary file, containing both model and result data. It can be used to post-process results in HyperView.
  - Animation Output File (A-File)
    The RunnameAnnn file is a binary file, containing both model and result data. It can be used to post-process results in HyperView.
  - ASCII Output File (STA-File)
    ASCII Output files are formatted output files from Radioss Starter and Radioss Engine.
  - ASCII Output File (STY-File)
    ASCII Output files are formatted output files from Radioss Starter and Radioss Engine.
  - Control File (C-File)
    The optional control file is used to get information about a currently running analysis.
  - External Modes File
    When computing eigen modes using Radioss (/EIG), for example to create an input file for a flexible body, CPU time and memory requirements can be greatly reduced if a set of approximated modes is already available.
  - Flexible Body Input File
    - Projected Matrices
      In order to solve dynamic equilibrium equations for a flexible body, projected mass and stiffness matrices are required.
    - Input File Format
      A flexible body input file is a formatted file whose name is given is the /FXBODY in Radioss Starter.
    - Create Flexible Body Input File without Radioss
      Computes the required data to write a flexible body input file without using Radioss.
    - Create Flexible Body Input File with Radioss
      /EIG in Radioss Starter is used to define the part of the model to be included in the flexible body, the type and number of modes to be computed.
- 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.

Create Flexible Body Input File with Radioss

/EIG in Radioss Starter is used to define the part of the model to be included in the flexible body, the type and number of modes to be computed.

In Radioss Engine, use /FXINP to create a Flexible Body Input File.

If a set of reduction modes for the flexible body is available, for example from a former experimental analysis or from a vibratory analysis performed with another software, they can be input in /EIG. They will be used to reduce the dimension of the space in which eigenvalues and eigenvectors are searched by Radioss and will greatly decrease the time and memory requirements to create the Flexible Body Input File.