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This manual provides a detailed list of all the input keywords and options available in Radioss.
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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.
Defense
Block Format Keyword
/DFS/LASER
Block Format Keyword Enable to model laser impact taking into account laser-matter interaction. topics/solvers/rad/dfs_laser_starter_r.html#dfs_laser_starter_r__dfs_laser_starter_r_fn_xpw_cfs_b1b

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View new features for Radioss 2025.1.
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Radioss^® is a leading explicit finite element solver for crash and impact simulation.
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This manual provides details on the features, functionality, and simulation methods available in Altair Radioss.
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This manual provides a detailed list of all the input keywords and options available in Radioss.
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    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.
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      Block Format Keyword
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      Block Format Keyword
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      Block Format Keyword
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      Block Format Keyword
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      Block Format Keyword
      - /DFS/DETCORD
        Block Format Keyword Set burning times of explosive material elements along a neutral fiber of detonating cord. Neutral fiber is provided with an ordered group of nodes and numerically built by spline interpolation.
      - /DFS/DETLINE
        Block Format Keyword Enable explosive material ignition from a detonation line [A,B].
      - /DFS/DETLINE/NODE
        Block Format Keyword Enable explosive material ignition from a detonation line [A,B].
      - /DFS/DETPLAN
        Block Format Keyword Describes a planar detonation wave.
      - /DFS/DETPLAN/NODE
        Block Format Keyword Describes a planar detonation wave.
      - /DFS/DETPOINT
        Block Format Keyword Locates the detonation point and set lighting time for an explosive material law.
      - /DFS/DETPOINT/NODE
        Block Format Keyword Locates the detonation point and set lighting time for an explosive material law.
      - /DFS/DETPOINT/SET
        Block Format Keyword Locates the detonation point defined in the node group and set lighting time for an explosive material law.
      - /DFS/LASER
        Block Format Keyword Enable to model laser impact taking into account laser-matter interaction. topics/solvers/rad/dfs_laser_starter_r.html#dfs_laser_starter_r__dfs_laser_starter_r_fn_xpw_cfs_b1b
      - /DFS/WAV_SHA
        Block Format Keyword Detonation times are computed taking into account an obstacle. The boundary of the obstacle is provided with an ordered group of nodes which defines the screen lines.
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      Block Format Keyword
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      Block Format Keyword
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      Block Format Keyword
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/DFS/LASER

Block Format Keyword Enable to model laser impact taking into account laser-matter interaction. 1

Format


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/DFS/LASER/`laser_ID`/`unit_ID`
`S`_LAS		`fct_ID`_LAS		`S`_TAR		`fct_ID`_TAR
`H`_n		`VC`_p		`K`₀		`R`_d		`K`_S
`N`_p	`N`_c
`IEL`₁	`IEL`₂	`IEL`₃	`IEL`₄	`IEL`₅	`IEL`₆	`IEL`₇	`IEL`₈	`IEL`₉	`IEL`₁₀
`IEL`₁₁	etc	`IEL`_Np

Definition


Field	Contents	SI Unit Example
`laser_ID`	Laser line identifier. (Integer, maximum 10 digits)
`unit_ID`	Unit identifier (Integer, maximum 10 digits)
`S`_LAS	Laser intensity scale factor. (Real)
`fct_ID`_LAS	Laser intensity time function number. (Real)
`S`_TAR	Target absorption scale factor. (Real)
`fct_ID`_TAR	Target absorption temperature function number. (Integer)	$[K]$
`H`_n	Plasma parameter. $H_{n} = \frac{h \cdot v}{k_{B}}$ Where, `h` Planck constant. `k`_B Boltzmann constant. `v` Laser frequency. (Real)	$[K]$
`VC`_p	Enthalpy of vaporization. (Real)	$[\frac{J}{kg \cdot K}]$
`K`₀	Inverse bremsstrahlung coefficient `K`₀. 6 (Real)	$[m^{5}]$
`R`_d	Inverse bremsstrahlung coefficient $\frac{R_{d}}{k_{B}}$ . 6 (Real)	$[K]$
`K`_S	Compliment absorption in vapor. 5 (Real)	$[\frac{m^{5}}{{mole}^{2}}]$
`N`_p	Number of plasma elements between laser and target. (Integer)
`N`_c	Target element number. 1 (Integer)
`IEL`_i	List of plasma elements (i=1,..., `N`_p). 3 (Integer)

Comments

Laser-matter interaction requires material laws enabling different phases: solid, liquid, and gas. It also needs to have a correct behavior with high pressure (several megabars) and high temperatures (more than 10000K). /MAT/LAW26 (SESAM) must also be used.
This option is available only in 2D analysis.
Plasma elements must be entered in the order from laser to target.
It is assumed the laser beam is perpendicular to the target.
$K_{S} = 67000 {(\frac{ρ}{w_{A}})}^{2}$ is taken from K. Daree's plasma ignition model.
$I = I_{0} - \sum_{n_{l a s e r}}^{n_{t a r g e t}} I_{a b s o r b e d}$

$I_{a b s o r b e d} = (1 - e^{- K Δ x}) I$

$K = \frac{4}{3} \sqrt{\frac{2 π}{3 k_{B} T}} \frac{n_{e} n_{i} Z^{2} e_{6}}{h c m_{e}^{\frac{3}{2}} v^{3}} (1 - e^{- \frac{h v}{k_{B} T}}) g f f = K_{0} {(\frac{R_{d}}{h v})}^{3} {(\frac{R_{d}}{k_{B} T})}^{\frac{1}{2}} (n_{i}^{2} Z^{3}) (1 - e^{- \frac{h v}{k_{B} T}}) g f f$

Usually, $K_{0} = 9.468 \times 10^{- 4} m^{5}$ and $\frac{R_{d}}{k} = 157750 K$ .