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User Subroutines
This manual describes the interface between Altair Radioss and user subroutines.
User Failure Models
In Radioss up to 3 user’s failure models (USER1, USER2, and USER3) can be defined for shell and solid elements.
Starter Subroutine LECRnn
This subroutine reads user failure model input data. The number of specific failure model cards and their formats are free.

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Overview
Radioss^® is a leading explicit finite element solver for crash and impact simulation.
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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.
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.
- Global User Window
  With Radioss, it is possible to define a global user window. This is the most general interface between Radioss and external code.
- Material Laws 29, 30, 31
  Up to 3 material user’s laws (law 29, 30 and 31) can be defined for 3D, 2D solid elements and 3D shell elements. User’s laws for beam or truss elements are not available.
- Extended Material Laws
  In Radioss, 99 material user laws can be defined for 3D and 2D solid elements, connection element, and 3D shell elements.
- User Property Elements
  Up to 3 spring user properties (property number 29, 30, and 31) can be defined for spring and solid elements.
- User Sensors
  In Radioss, up to three types of user sensors can be defined.
- User Failure Models
  In Radioss up to 3 user’s failure models (USER1, USER2, and USER3) can be defined for shell and solid elements.
  - Starter Subroutine LECRnn
    This subroutine reads user failure model input data. The number of specific failure model cards and their formats are free.
  - Engine Subroutine FnnLAW for Solid Elements
    This subroutine calculates the criteria of failure model.
  - Engine Subroutine FnnLAWC for Shell Elements
    This subroutine calculates the criteria of the failure model.
  - User Failure Model Examples
    Examples of Subroutine for Shell and Solid elements.
- Write in Output Files
  Some user subroutines do not pass the IOUT file descriptor and, thus, do not permit writing in a Radioss output file.
- Generate Radioss User Libraries
  Radioss user libraries are built on Windows and Linux with two different compilers: Intel Fortran or Gfortran.
- Initialize, Verify and Finalize
  The workflow in some user options may require initialization, verify during the run and finalize tasks in the Engine.
- Appendix

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Starter Subroutine LECRnn

This subroutine reads user failure model input data. The number of specific failure model cards and their formats are free.

Arguments

The argument list of LECRnn and its individual arguments and descriptions are:

C----------------------------------------------------------------------------
      SUBROUTINE LECRnn (IIN ,IOUT ,UPARAM ,MAXUPARAM,NUPARAM,  NUVAR,IFUNC,MAXFUNC,NFUNC)
C----------------------------------------------------------------------------

Definition


Argument	Format	Description
`IIN`	Integer read only scalar	Input file unit (ROOT_nnn0.rad) on which the data are read.
`IOUT`	Integer read only format	Output file unit (ROOT_nnn0.out).
`UPARAM`	Float array	Array with a size `NUPARAM` used to store failure material data.
`MAXUPARAM`	Integer read only scalar	Maximum possible size of `UPARAM`.
`NUPARAM`	Integer scalar	Effective size of `UPARAM`. (`MAXUPARAM`, `NUPARAM`, `MAXUPARAM` are set to 1000).
`NUVAR`	Integer scalar	Number of extra variables needed for each integration point of each elements.
`IFUNC`	Integer array	Array with a size of `NFUNC` containing the list of Radioss functions used in failure model. The function numbers are stored in this array (not in `UPARAM`) due to a possible renumbering of the function’s numbers.
`MAXFUNC`	Integer read only scalar	Maximum possible size of `IFUNC`.
`NFUNC`	Integer scalar	Number of Radioss functions.