/LEAK/MAT
Block Format Keyword Specifies effective leakage area of porous airbag fabric materials LAW19 and LAW58 as function of time, pressure, area and other parameters.
Format
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

/LEAK/MAT/mat_ID/unit_ID  
mat_title  
Ileakage  Ascale_{T}  Ascale_{P} 
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

AC'  fct_ID_{AC'}  Fscale_{AC'} 
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

LC  AC 
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

fct_ID_{LC}  fct_ID_{AC}  Fscale_{LC}  Fscale_{AC} 
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

L  R  
C_{1}  C_{2}  C_{3} 
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

X_{0}  X_{1}  X_{2}  X_{3} 
Definitions
Field  Contents  SI Unit Example 

mat_ID  Material
identifier (Integer, maximum 10 digits) 

unit_ID  Unit Identifier (Integer, maximum 10 digits) 

mat_title  Material
title (Character, maximum 100 characters) 

Ileakage  Effective leakage area
formulation flag.
(Integer) 

Ascale_{T}  Abscissa time scale factor
on function Default = 1 (Real) 

Ascale_{P}  Abscissa pressure scale
factor on function Default = 1 (Real) 

AC'  Area coefficient for area
in contact
$0\le AC\text{'}\le 1$
Default = 0 (Real) 

fct_ID_{AC'}  Area coefficient function
identifier AC'(t) if AC' is equal to 0 (Integer) 

Fscale_{AC'}  Scale factor on function
AC' Default=1 (Real) 

LC  Leakage
coefficient Default function is 0 (Real) 

AC  Area coefficient Default = 0 (Real) 

fct_ID_{LC}  Leakage coefficient
function identifier LC(t), if Ileakage
=2 or 3 Leakage coefficient function identifier $LC\left(Area/Are{a}_{0}\right)$ , if Ileakage =4 Default function is 0 (Integer) 

Fscale_{LC}  Scale factor on function
LC Default = 1 (Real) 

fct_ID_{AC}  Area coefficient function
identifier
$AC\left(P\right)$
, if Ileakage
=2. Area coefficient function identifier $AC\left(P{P}_{ext}\right)$ , if Ileakage =3. Area coefficient function identifier $AC\left({P}_{ext}/P\right)$ , if Ileakage =4. Default function is 0 (Integer) 

Fscale_{AC}  Scale factor on function
AC Default = 1 (Real) 

L  Characteristic
length Default = 1 (Real) 
$\left[\text{m}\right]$ 
R  Fiber thickness Default = L (Real) 
$\left[\text{m}\right]$ 
C_{1}  Coefficient
C1 (Real) 

C_{2}  Coefficient C2 Default = 1 (Real) 

C_{3}  Coefficient
C3 (Real) 

X_{0}, X_{1}, X_{2}, X_{3}  Coefficients of
AnagonyeWang leakage area law (Real) 
Comments
 The mat_ID must be the same as /MAT/LAW19 (FABRI) or /MAT/LAW58 (FABR_A). Material porosity is active only when corresponding components are referred as external surfaces in /MONVOL/AIRBAG1, /MONVOL/COMMU1, and /MONVOL/FVMBAG1 airbag cards.
 Effective leakage area (
${A}_{eff}$
) formulation:Ileakage =1:
(1) $${A}_{eff}={\displaystyle \sum _{n}LC\cdot AC\cdot}Are{a}_{n}$$Ileakage =2:(2) $${A}_{eff}={\displaystyle \sum _{n}\mathrm{LC}(t)\cdot \mathrm{AC}(P)}\cdot Are{a}_{n}$$Ileakage =3:(3) $${A}_{eff}={\displaystyle \sum _{n}\mathrm{LC}(t)\cdot \mathrm{AC}(PPext)}\cdot Are{a}_{n}$$Ileakage =4:(4) $${A}_{eff}={\displaystyle \sum _{n}\mathrm{LC}(Are{a}_{n}/Are{a}_{0})\cdot \mathrm{AC}({P}_{ext}/P)}\cdot Are{a}_{n}$$Where, $Are{a}_{0}$
 Initial area of the airbag surface
Note: By default all coefficients and functions are zero.Ileakage =5:(5) $${A}_{eff}={\displaystyle \sum _{n}\frac{Are{a}_{0}}{{L}^{2}}}\left[({C}_{1}\text{\Delta}{P}^{{C}_{2}}{C}_{3}){(LR)}^{2}+{C}_{3}(L{\lambda}_{1}R/\sqrt{{\lambda}_{2}})(L{\lambda}_{2}R/\sqrt{{\lambda}_{1}})\right]\cdot \mathrm{sin}{\alpha}_{12}$$$\text{\Delta}P=P/{P}_{ext}1$
Where, ${\lambda}_{1}$ and ${\lambda}_{2}$ are the stretches in warp and weft directions and ${\alpha}_{12}$ is the angle between warp and weft directions.Note: For LAW19 ${\alpha}_{12}={90}^{\circ}$Ileakage =6:(6) $${A}_{eff}={\displaystyle \sum _{n}Are{a}_{0}}({X}_{0}+{X}_{1}{r}_{s}+{X}_{2}{r}_{p}+{X}_{3}{r}_{s}{r}_{p})$$with ${r}_{s}=Are{a}_{n}/Are{a}_{0}$ and ${r}_{p}={P}_{ext}/P$
 Blockage of airbag fabric, due to
contact, can be activated in corresponding /MONVOL card.
Effective leakage area is calculated with account of the blockage as:
(7) $$Are{a}_{n}=Are{a}_{non\_impacted}+A{C}^{\prime}\cdot Are{a}_{impacted}$$