2021

2021

*AIRBAG_SIMPLE_AIRBAG_MODEL

LS-DYNA Input Interface KeywordThis model defines a one-chambered airbag with uniform pressure method, injected gas and vent hole.

Format

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*AIRBAG_SIMPLE_AIRBAG_MODEL_{OPTION}

If OPTION = ID, insert the following line.

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`monvol_ID`	`Title`

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)
`surf_IDex`	`Surf_typ`
`CV`	`CP`	`T`	`Fct_IDM`	`MU`	`AREA`	`Pext`
	`Text`	`Cpa`	`Cpb`	`MW`

Definition

Field	Contents	SI Unit Example
`monvol_ID`	Airbag Identifier (Integer)
`Title`	Title (character)
`surf_IDex`	Airbag external surface identifier (Integer)
`Surf_typ`	Set type = 0 Default The `surf_Idex` is a segment ≠ 0 The `surf_Idex` is a set of parts. (Integer)
`CV`	Heat capacity at constant volume. 2 (Real)	$[\frac{J}{kg \cdot K}]$
`CP`	Heat capacity at constant pressure (Real)	$[\frac{J}{kg \cdot K}]$
`T`	Input gas temperature (Real)	$[K]$
`Fct_IDM`	Mass flow rate of injected gas vs. time function identifier. (Integer)
`MU`	Vent hole shape < 0 Function identifier of shape factor versus absolute pressure Default = 1 (Real)
`Area`	Vent hole area < 0 Area > 0 Function identifier of area versus absolute pressure (Real)	$[{mm}^{2}]$
`Pext`	External pressure (Real)	$[Pa]$
`Text`	External temperature Default = 295 K (Real)	$[K]$
`Cpa`	First heat capacity coefficient of injected gas (Real)	$[\frac{J}{mole .K}]$
`Cpb`	First heat capacity coefficient of injected gas (Real)	$[\frac{J}{m o l e \cdot K^{2}}]$
`MW`	Molecular weight of gas (Real > 0)	$[\frac{k g}{m o l e}]$

Comments

This keyword maps to /MONVOL/AIRBAG1, /MAT/GAS, and /PROP/INJECT1.
If CV = 0, specific heat parameters are computed as:
$C p = \frac{(a + b T)}{M W}$ , $C v = C p - \frac{R}{M W}$