/MAT/LAW114 (SPR_SEATBELT)
Block Format Keyword This spring material is designed for 1D seatbelt elements.
Format
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

/MAT/LAW114/mat_ID/unit_ID or /MAT/SPR_SEATBELT/mat_ID/unit_ID  
mat_title  
$\rho $  Lmin  
K  C  
fct_load  fct_uload  Xscale  Fscale  
E  I  J  Fmax  Mmax  
AS  R 
Definition
Field  Contents  SI Unit Example 

mat_ID  Material identifier. (Integer, maximum 10 digits) 

unit_ID  (Optional) Unit
identifier. (Integer, maximum 10 digits) 

mat_title  Material title. (Character, maximum 100 characters) 

$\rho $  Density. (Real) 
$\left[\frac{\text{kg}}{{\text{m}}^{\text{3}}}\right]$ 
Lmin  Minimum length for mass
computation. Default = 1% of average mesh size (Real) 
$\left[\text{m}\right]$ 
K  Linear loading and unloading
stiffness per unit length. Used only if fct_load is not defined. (Real) 
$\left[\text{N}\right]$ 
C  Damping. If not defined, a small amount of damping is automatically applied. 9 (Real) 
$\left[\text{N}\text{s}\right]$ 
fct_load  Function identifier defining
loading force versus engineering strain
$f\left(\epsilon \right)$
. (Integer) 

fct_uload  Function identifier defining
unloading force versus engineering strain
$f\left(\epsilon \right)$
. Not used when element is inside slipring or retractors. (Integer) 

Xscale  Scale factor for
$\text{\epsilon}$
for fct_load and
fct_uload. Default = 1.0 (Real) 

Fscale  Scale factor for
$f\left(\epsilon \right)$
for fct_load
and fct_uload. Default = 1.0 (Real) 
$\left[\text{N}\right]$ 
E  Young's modulus for compression and
bending. (Real) 
$\left[\text{Pa}\right]$ 
I  Area moment of inertia
bending. (Real) 
$\left[{\text{m}}^{4}\right]$ 
J  Area moment of inertia
torsion. (Real) 
$\left[{\text{m}}^{4}\right]$ 
Fmax  Maximum force for shear and
compression. (Real) 
$\left[\text{N}\right]$ 
Mmax  Maximum moment for bending and
torsion. (Real) 
$\left[\text{Nm}\right]$ 
AS  Shear area. (Real) 
$\left[{\text{m}}^{2}\right]$ 
R  Scaling factor for
inertia. Default = 1.0 (Real) 
Example (Seatbelt)
#RADIOSS STARTER
#12345678910
/UNIT/1
Seatbelt
Mg mm s
#12345678910
/MAT/SPR_SEATBELT/1/1
Seatbelt
# Density Lmin
1E6 0
# KTens CTens
10000 1.1
# fct_load fct_uload Xscale Fscale
0 0 0 0
# E I J FMAX MMAX
0 0 0 0 0
# AS R
0 0
#12345678910
#ENDDATA
/END
#12345678910
Comments
 The tension behavior can be defined as linear elastic if K > 0 and fct_load = 0.
 Loading curve (fct_load > 0) is used both for loading and unloading when unloading curve is not defined (fct_uload = 0).
 By default, there is no compression, so function fct_load and fct_uload must be input only for positive strain.
 The behavior in compression can be defined with youngs modulus (E), in that case the behavior can only be perfectly plastic, maximum force being defined by Fmax.
 Bending and torsion behavior are also defined using Young's modulus, area and area of inertia. The behavior is perfectly plastic.
 When the seatbelt element is inside a retractor or a slipring, unloading curve is not used.
 Damping is not applied when the element is inside a slipring and retractor.
 Minimum length is used only in case of sliprings (/SLIPRING/*) and retractors (/RETRACTOR/*) to prevent stiffness becoming infinite.
 It is recommended to use damping for seatbelts. If C = 0, a small amount of critical damping is automatically applied.