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Radioss 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.
Initial Conditions
Block Format Keyword
/INISHE or /INISH3
/INISHE/FAIL or /INISH3/FAIL
Block Format Keyword Describes the failure criteria for a shell.

Welcome
What's New
View new features for Radioss 2026.
Radioss Overview
Radioss is a leading explicit finite element solver for crash and impact simulation.
Tutorials
Discover Radioss functionality with interactive tutorials.
Radioss User Guide
This manual provides details on the features, functionality, and simulation methods available in Altair Radioss.
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 2026
  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
      - /INIBEAM
      - /INIBRI
        Describes the different initial state for a brick. The initial state for brick may be defined by more than one block.
      - /INICRACK
        Block Format Keyword Definition of the initial crack.
      - /INIGRAV
        Block Format Keyword Defines initial state from hydrostatic pressure due to gravity loading.
      - /INIMAP1D
        Block Format Keyword Map 1D velocities and thermodynamic values into 2D or 3D space using spherical, cylindrical, or planar mapping methods. The mapped results are used with /ALE/EULER materials.
      - /INIMAP1D/FILE
        Block Format Keyword Map 1D velocities and thermodynamic values into 2D or 3D space using spherical, cylindrical, or planar mapping methods. The mapped results are used with /ALE/EULER materials.
      - /INIMAP2D
        Block Format Keyword Map 2D velocity and thermodynamic values into a 3D axi-symmetric space for use with /ALE/EULER materials.
      - /INIMAP2D/FILE
        Block Format Keyword Map 2D velocity and thermodynamic values into a 3D axi-symmetric space for use with /ALE/EULER materials.
      - /INIQUA
        Block Format Keyword Describes the different initial state for a quad element.
      - /INISHE or /INISH3
        /INISHE/AUX or /INISH3/AUX
        Block Format Keyword This option is used to initialize internal variables of user type material laws for shells (UVAR buffer).
        /INISHE/EPSP_F or /INISH3/EPSP_F
        Block Format Keyword Describes the initial plastic strain for a shell in each integration point.
        /INISHE/FAIL or /INISH3/FAIL
        Block Format Keyword Describes the failure criteria for a shell.
        /INISHE/ORTH_LOC or /INISH3/ORTH_LOC
        Block Format Keyword Describes the initialization of orthotropy direction for shells element per element.
        /INISHE/ORTHO or /INISH3/ORTHO
        Block Format Keyword Describes the initialization of orthotropy direction for shells element per element.
        /INISHE/SCALE_YLD or /INISH3/SCALE_YLD
        Block Format Keyword This option is used to set a scale factor for yield stress per element for shells.
        /INISHE/STRA_F or /INISH3/STRA_F
        Block Format Keyword This describes the initial state for strain.
        /INISHE/STRA_F/GLOB or /INISH3/STRA_F/GLOB
        Block Format Keyword Describes the initialization strain for shell elements in the global coordinate system.
        /INISHE/STRS_F or /INISH3/STRS_F
        Block Format Keyword Describes the initial state of stress.
        /INISHE/STRS_F/GLOB or /INISH3/STRS_F/GLOB
        Block Format Keyword Describes the initialization of stress tensor given in global coordinate system for shell elements.
        /INISHE/THICK or /INISH3/THICK
        Block Format Keyword Describes the initialization of thickness for shells element per element.
      - /INISPHCEL/FULL
        Block Format Keyword Describes the initial state for a Smooth Particle Hydrodynamic (SPH).
      - /INISPRI/FULL
        Block Format Keyword Describes the initial state for spring elements. All values defined in this card will be applied at the beginning on the computation.
      - /INISTA
        Block Format Keyword Describes the initial state file.
      - /INITEMP
        Block Format Keyword Describes the initial nodal temperature.
      - /INITRUSS/FULL
        Block Format Keyword Describes the initial state for truss elements. All values defined in this card will be applied at the beginning on the computation.
      - /INIVEL
        Block Format Keyword Defines initial velocity on a group of nodes.
      - /INIVEL/AXIS
        Block Format Keyword Initialize both translational and rotational velocities on a group of nodes in a given coordinate system.
      - /INIVEL/FVM
        Block Format Keyword Defines initial material velocities on a group of elements (bricks, quad or triangles) for the Finite Volume solver.
      - /INIVEL/NODE
        Block Format Keyword Initialize translational and rotational velocities on each node in the global or in a given coordinate system.
      - /INIVOL
        Block Format Keyword For multi-material ALE modeling, this initial condition defines the initial volumetric fractions on a side of a defined surface.
      - /STATE/STR_FILE
        Block Format Keyword Allows to read an initial state (blocks /INISHE, /INISH3, and /INIBRI) by specifying the name of a stress file possibly compressed using GZIP.
    - Load
      Block Format Keyword
    - 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.
- 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.
- Multi-Domain
  This manual contains the description of the keywords for the Radioss Multi-Domain.
- Obsolete Keywords
  Keywords that are still supported, but no longer maintained (*) are considered obsolete.
- Other Files
- Definition
Radioss Example Guide
This manual presents examples solved using Radioss with regard to common problem types.
Radioss Verification Problems
This manual presents solved verification models.
Radioss Frequently Asked Questions
This section provides quick responses to typical and frequently asked questions regarding Radioss.
Radioss Theory Manual
This manual provides detailed information about the theory used in the Altair Radioss Solver.
Radioss User Subroutines
This manual describes the interface between Altair Radioss and user subroutines.

View All Altair HyperWorks Help

/INISHE/FAIL or /INISH3/FAIL

Block Format Keyword Describes the failure criteria for a shell.

Format


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/INISHE/FAIL/`unit_ID` or /INISH3/FAIL/`unit_ID`
`shell_ID`	`N`_lay	`npg`	`nptt`	`lay_ID`	`fail_ID`	`Ifail_typ`	`N`_var	`mat_ID`
`V`₁		etc		etc
		`V`_N

Definition


Field	Contents	SI Unit Example
`unit_ID`	Unit identifier. (Integer, maximum 10 digits)
`shell_ID`	Element identifier. (Integer)
`N`_lay	Number of layers. (Integer)
`npg`	Number of surface quadrature points. = 0 (Default) Set to 1 = 1 Must be used for shell formulations `shell_ID` =1, 2, 3, 4, 24 or `I`_sh3n =1, 2, 31. = 3 Must be used for DKT18 shell formulation (`I`_sh3n =30). = 4 Must be used for BATOZ formulation (`shell_ID` =12). (Integer)
`nptt`	Integration point number through the thickness. It corresponds to the property definition of this element. (Integer)
`lay_ID`	Layer to initialize identifier. (Integer)
`fail_ID`	Failure criteria to initialize identifier. (Integer)
`Ifail_typ`	Failure criteria number to initialize. 2 (Integer)
`N`_var	Number of failure criteria variables to initialize. (Integer)
`mat_ID`	Material identifier to initialize. (Integer)
`V`₁	First failure criteria variable value. (Integer)
`V`_N	`N`^th failure criteria variable (3 values per line). (Integer)

Comments

If npg > 1, nptt > 1, and Nlay > 1, the lines with Real values have to be repeated for each integration point.
Every failure model has a Ifail_typ which is used to identify the failure model to initialize for the element. Verify failure law to element type compatibility in /FAIL.

Keyword

Ifail_typ

/FAIL/ALTER

28

/FAIL/BIQUAD

30

/FAIL/CHANG

13

/FAIL/COCKCROFT

34

/FAIL/CONNECT

20

/FAIL/EMC

27

/FAIL/ENERGY

11

/FAIL/FABRIC

31

/FAIL/FLD

7

/FAIL/FRACTAL_DMG

12

/FAIL/GENE1

39

/FAIL/GURSON

35

/FAIL/HASHIN

14

/FAIL/HC_DSSE

32

/FAIL/HOFFMAN

46

/FAIL/INIEVO

42

/FAIL/JOHNSON

1

/FAIL/LAD_DAMA

18

/FAIL/MAXSTRAIN

47

/FAIL/MULLINS_OR

33

/FAIL/NXT

25

/FAIL/ORTHBIQUAD

38

/FAIL/ORTHENERG

48

/FAIL/ORTHSTRAIN

24

/FAIL/PUCK

16

/FAIL/RTCL

40

/FAIL/SAHRAEI

29

/FAIL/SNCONNECT

26

/FAIL/SPALLING

8

/FAIL/SYAZWAN

43

/FAIL/TAB1

23

/FAIL/TAB2

41

/FAIL/TBUTCHER

2

/FAIL/TENSSTRAIN

10

/FAIL/TSAIHILL

45

/FAIL/TSAIWU

44

/FAIL/USER1

4

/FAIL/USER2

5

/FAIL/USER3

6

/FAIL/VISUAL

36

/FAIL/WIERZBICKI

9

/FAIL/WILKINS

3