/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 | |||||||||
ρ | 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) |
|
ρ | Density. (Real) |
[kgm3] |
Lmin | Minimum length for mass
computation. Default = 1% of average mesh size (Real) |
[m] |
K | Linear loading and unloading
stiffness per unit length. Used only if fct_load is not defined. (Real) |
[N] |
C | Damping. If not defined, a small amount of damping is automatically applied. 9 (Real) |
[Ns] |
fct_load | Function identifier defining
loading force versus engineering strain
f(ε)
. (Integer) |
|
fct_uload | Function identifier defining
unloading force versus engineering strain
f(ε)
. Not used when element is inside slipring or retractors. (Integer) |
|
Xscale | Scale factor for
ε
for fct_load and
fct_uload. Default = 1.0 (Real) |
|
Fscale | Scale factor for
f(ε)
for fct_load
and fct_uload. Default = 1.0 (Real) |
[N] |
E | Young's modulus for compression and
bending. (Real) |
[Pa] |
I | Area moment of inertia
bending. (Real) |
[m4] |
J | Area moment of inertia
torsion. (Real) |
[m4] |
Fmax | Maximum force for shear and
compression. (Real) |
[N] |
Mmax | Maximum moment for bending and
torsion. (Real) |
[Nm] |
AS | Shear area. (Real) |
[m2] |
R | Scaling factor for
inertia. Default = 1.0 (Real) |
▸Example (Seatbelt)
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 Young's 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.