# MONVOL

Bulk Data Entry Defines a one-chamber gas filled structure with hybrid input of inflated gas.

Attention: Valid for Explicit Analysis only

## Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
MONVOL MID   UNIT
SURF SID
AMBIENT PATM TATM
Optional continuation line to define properties of the initial gas inside the structure.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
IAIR PAIR TAIR
XMAIR Cpa_air Cpb_air Cpc_air Cpd_air Cpe_air
Optional continuation line to define a vent hole. It can be repeated as required.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
+ VENT SIDV C23 LCTC23 LCPC23 PDEF
Optional continuation line to define properties of the injected gas. It can be repeated as required.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
+ MATGAS LCM LCT
XM $Cpa$ $Cpb$ $Cpc$ $Cpd$ $Cpe$

## Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
MONVOL 1
SURF 10
AMBIENT 1.013E5 293.0
MATGAS 3 4
0.004 40.0 0.0 0.0
IAIR 1.013E5 293.0
0.028 28.0 0.0 0.0

## Description

Field Contents SI Unit Example
MID Monitor volume identification number.

No default (Integer > 0)

UNIT Unit system.
0 (Default)
kg-mm-ms-K
1
kg-m-s-K (SI units)
2
ton-mm-s-K

SURF Flag to indicate the external surface of enclosed volume.
SID External surface identification defined by a set of elements.

No default (Integer > 0)

ATM Flag to indicate that the two following fields define atmospheric pressure and temperature.
TATM Ambient temperature.

Default=293 K (Real ≥ 0.0)

PATM Ambient pressure.

Default=1 atm (Real ≥ 0.0)

VENT Flag to indicate that the following five fields indicate the vent hole properties.
SIDV Vent hole area surface identification number.

No default (Integer > 0)

C23 Scale factor on vent hole area.

Default=1.0 (Real > 0.0)

LCTC23 Curve defining vent hole coefficient as a function of time.

No default (Integer > 0)

LCPC23 Curve defining vent hole coefficient as a function of pressure.

No default (Integer > 0)

PDEF Pressure difference between interior and ambient pressure to open vent hole.

Default=0.0

MATGAS Flag to indicate that the following four fields define the inflated gas properties.
LCM Table that defines mass flow rate curve for the gas component.
LCT Table that defines temperature curve for the gas component.
XM Molar mass of the gas component.
Cpa, Cpb, Cpc, Cpd, Cpe Molar heat capacity coefficients of the inflow gas at constant pressure. 4
IAIR Flag to indicate that the following four fields define properties of the initial gas inside the structure.
PAIR Initial pressure inside structure.

Default=PATM (Real ≥ 0.0)

TAIR Initial temperature inside structure.

Default=TATM (Real ≥ 0.0)

XMAIR Molar mass of air initially inside structure.

No default (Real ≥ 0.0)

Cpa_air, Cpb_air, Cpc_air, Cpd_air, Cpe_air Molar heat capacity coefficients of the initial air at constant pressure. 4

No default (Real ≥ 0.0)

1. The volume must be a completely enclosed volume and the norm must be oriented outwards. If the structure contains a vent hole, the vent hole must be meshed with a shell element.
2. The value of the total vent hole coefficient must be between 0.0 and 1.0:(1)

Total vent hole coefficient = min(max(C23 × LCTC23 × LCPC23, 0.0), 1.0).

3. There is no limit on the number of gas components.
4. Heat capacity at constant pressure:(2)
$Cp=Cpa+CpbT+Cpc{T}^{2}+Cpd{T}^{3}+\frac{Cpe}{T}$

Where, $T$ is temperature.

5. Support information for MONVOL:
Supported Analysis Types
Explicit Dynamic Analysis