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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.
Monitored Volumes (Airbags)
Block Format Keyword Monitored volumes can be used to model an airbag, tire, tank, or any closed volume.
/MONVOL/PRES
Block Format Keyword Describes the pressure load curve monitored volume type.

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What's New
View new features for Radioss 2024.1.
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.
    - /MONVOL/AIRBAG1
      Block Format Keyword Describes one-chambered airbag with hybrid input of injected gas. This keyword is similar to /MONVOL/AIRBAG (Obsolete), but has more flexible input.
    - /MONVOL/AREA
      Block Format Keyword Describes the monitored volume type AREA.
    - /MONVOL/COMMU1
      Block Format Keyword Describes multi-chambered airbag with hybrid input of injected gas. This keyword is similar to /MONVOL/COMMU (Obsolete), but has more flexible input.
    - /MONVOL/FVMBAG1
      Block Format Keyword Describes Finite Volume Method Airbag, which has more flexible input than the similar obsolete keyword /MONVOL/FVMBAG (Obsolete).
    - /MONVOL/FVMBAG2
      Block Format Keyword Describes Finite Volume Method Airbag, which has simplified input, similar to /MONVOL/FVMBAG1.
    - /MONVOL/GAS
      Block Format Keyword Describes the perfect gas monitored volume type.
    - /MONVOL/LFLUID
      Block Format Keyword Describes the pressure of a linear fluid using a monitored volume.
    - /MONVOL/PRES
      Block Format Keyword Describes the pressure load curve monitored volume type.
    - /PROP/INJECT1
      Block Format Keyword Describes mass injected for each constituent gas.
    - /PROP/INJECT2
      Block Format Keyword Describes molar fraction injected for each constituent gas and total mass injected.
  - 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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/MONVOL/PRES

Block Format Keyword Describes the pressure load curve monitored volume type.

Format


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/MONVOL/PRES/`monvol_ID`/`unit_ID`
`monvol_title`
`surf_ID`_ex
`Ascale`_t
`fct_ID`	`Fscale`			`Itypfun`

Definition


Field	Contents	SI Unit Example
`monvol_ID`	Monitored volume identifier. (Integer, maximum 10 digits)
`unit_ID`	Unit identifier. (Integer, maximum 10 digits)
`monvol_title`	Monitored volume title. (Character, maximum 100 characters)
`surf_ID`_ex	External surface identifier. (Integer)
`Ascale`_t	Abscissa scale factor for time based functions. 4 (Real)	$[s]$
`fct_ID`	Load curve identifier for relative pressure. If `Itypfun`=0, the function defines $P_{r e l} = f c t_I D (\frac{V_{0}}{V})$ If `Itypfun`=1, the function defines $P_{r e l} = f c t_I D (t)$ If `Itypfun`=2, the function defines $P_{r e l} = f c t_I D (\frac{V}{V_{0}})$ If `Itypfun`=3, the function defines $P_{r e l} = f c t_I D (t) * (\frac{V_{O}}{V})$ (Integer)
`Fscale`	Load curve scale factor for relative pressure. 4 Default = 1.0 (Real)	$[Pa]$
`Itypfun`	Flag type of relative pressure function defined in `fct_ID`. =0 Pressure is $P_{r e l} = f c t_I D (\frac{V_{0}}{V})$ = 1 Pressure is $P_{r e l} = f c t_I D (t)$ =2 Pressure is $P_{r e l} = f c t_I D (\frac{V}{V_{0}})$ =3 Pressure is $P_{r e l} = f c t_I D (t) * (\frac{V_{O}}{V})$ (Integer)

Comments

The relative pressure is defined as, Prel = pressure inside of monitored volume - atmospheric pressure.
surf_ID_ex must be defined using segments associated with 4- or 3-nodes shell elements (possibly void elements) and not with /SURF/SEG.
The volume must be closed and the normals must be oriented outwards.
Abscissa scale factors are used to transform abscissa units in airbag functions, for example:
$F (t') = fct_{ID}_{t} = f (\frac{t}{{Ascale}_{t}})$
Where, $t$ is time.
$F (P') = f c t_I D_{P} = f (\frac{P_{r e l}}{F s c a l e})$
Where, $P_{r e l}$ is relative pressure.