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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.
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.
Load
Block Format Keyword
/CLOAD
Block Format Keyword Defines a concentrated force or moment applied to each node of a prescribed nodal group.

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View new features for Radioss 2024.
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.
- 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).
  - 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.
    - Initial Conditions
      Block Format Keyword
    - Load
      Block Format Keyword
      - /BEM/DAA
        Block Format Keyword Doubly Asymptotic Approximation for Underwater Explosion, where the fluid mass matrix is computed by boundary element method.
      - /BEM/FLOW
        Block Format Keyword Describes the incompressible fluid flow by boundary elements method.
      - /CLOAD
        Block Format Keyword Defines a concentrated force or moment applied to each node of a prescribed nodal group.
      - /GRAV
        Block Format Keyword Defines gravity load on node group.
      - /LOAD/CENTRI
        Block Format Keyword Apply a centrifugal force on a set of nodes according a body rotational velocity around the defined direction.
      - /LOAD/PBLAST
        Block Format Keyword Provides a fast way to simulate air blast pressure on a structure.
      - /LOAD/PCYL
        Block Format Keyword Defines a pressure load in a cylindrical system on a surface as a function of radius, time and angle of incidence.
      - /LOAD/PFLUID
        Block Format Keyword This entry provides a simple way to simulate hydrodynamic fluid pressure on a structure. The fluid pressure is calculated according to the specified fluid velocity, orientation of the structural surface against the fluid vector and the height of the fluid column above the surface of the structure.
      - /LOAD/PRESSURE
        Block Format Keyword Defines pressure load on a surface for 3D surface.
      - /PLOAD
        Block Format Keyword Defines pressure load on a surface.
      - /PRELOAD
        Block Format Keyword Defines a preloading stress applied to the section of a 3D bolt.
    - Thermal
      Block Format Keyword
    - Reference State
      Block Format Keyword
    - Defense
      Block Format Keyword
    - ALE Elementary Boundary Conditions
      Block Format Keyword
    - ALE and CFD Constraints
      Block Format Keyword
    - SPH Constraints
      Block Format Keyword
  - 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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/CLOAD

Block Format Keyword Defines a concentrated force or moment applied to each node of a prescribed nodal group.

Format


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/CLOAD/`cload_ID`/`unit_ID`
`cload_title`
`fct_ID`_T	`Dir`	`skew_ID`	`sens_ID`	`grnd_ID`		`Ascale`_x		`Fscale`_y

Definition


Field	Contents	SI Unit Example
`cload_ID`	Concentrated load block identifier. (Integer, maximum 10 digits)
`unit_ID`	Unit Identifier. (Integer, maximum 10 digits)
`cload_title`	Concentrated load block title. (Character, maximum 100 characters)
`fct_ID`_T	Time function identifier. (Integer)
`Dir`	Direction of load: X, Y, and Z for forces; XX, YY, and ZZ for moments. (Text)
`skew_ID`	Skew identifier. (Integer)
`sens_ID`	Sensor identifier. ≠ 0 The concentrated load is applied after sensor activation (the time function is shifted in time). (Integer)
`grnd_ID`	Node group to which the concentrated loads are applied. (Integer)
`Ascale`_x	Abscissa scale factor. Default = 1.0 (Real)	$[s]$
`Fscale`_y	Ordinate scale factor. Default = 1.0 (Real)	$[N]$

Comments

The direction of load must be right justified in the ten characters of field number 2.
The grnd_ID input is obligatory. The concentrated loads will only be applied to the nodal group. The force is applied to each node individually, so:
$t o t a l_f o r c e = F (t) \cdot N_{n o d e}$
with $N_{n o d e}$ being the number of nodes in the node group.
The Ascale_x and Fscale_y are used to scale the abscissa and ordinate.
The actual load function value is calculated as:
$F (t) = F s c a l e_{y} \cdot f_{T} \cdot (\frac{t}{A s c a l e_{x}})$
Where, $f_{T}$ is the function of fct_ID_T.
The force is applied individually to each node of the nodal group. The total force is equivalent to the force value multiplied by the number of nodes.