/RETRACTOR/SPRING
Block Format Keyword Define 1D retractor for seatbelt defined with material /MAT/LAW114 and property /PROP/TYPE23.
Format
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
/RETRACTOR/SPRING/retractor_ID/unit_ID | |||||||||
retractor_title | |||||||||
El_ID | node_ID | Elem_size | |||||||
sens_ID1 | Pull_Lock | fct_ID1 | fct_ID2 | Yscale1 | Xscale1 | ||||
sens_ID2 | Typ_pre | Fmax | fct_ID3 | Yscale2 | Xscale2 |
Definitions
Field | Contents | SI Unit Example |
---|---|---|
retractor_ID | Retractor
identifier. (Integer) |
|
unit_ID | (Optional) Unit
identifier. (Integer) |
|
retractor_title | Retractor title. (Character, maximum 100 characters) |
|
El_ID | Element ID initially connected to
retractor. (Integer, maximum 10 digits) |
|
node_ID | Anchorage node ID. 1 (Integer) |
|
Elem_size | Target element size for released
elements. 4 (Real) |
|
sens_ID1 | Sensor identifier for retractor
locking. 3 (Integer) |
|
Pull_Lock | Authorized amount of seatbelt
release before locking. 6 (Real) |
|
fct_ID1 | Function identifier defining
loading force scale factor versus pullout when retractor is
locked. 5 (Integer) |
|
fct_ID2 | Function identifier defining
unloading force scale factor versus pullout when retractor is
locked. 5 (Integer) |
|
Yscale1 | Retractor force. If fct_ID1= 0: constant force (Default = 0) If fct_ID1 ≠ 0: ordinate scaling factor for fct_ID1 and fct_ID2 (Default = 1). (Real) |
|
Xscale1 | Abscissa scaling factor for
function fct_ID1 and fct_ID2. Default = 1 (Real) |
|
sens_ID2 | Sensor identifier used for
pretension activation. 7 (Integer) |
|
Typ_pre | Pretensioner type. 8
Default = (Integer) |
|
Fmax | Maximum retractor force for
pretensioner locking (for Typ_pre =
1 and 5
only). (Real) |
|
fct_ID3 | Function identifier defining
pretension as a function of time, force versus time, length
versus time, or energy versus time. 8 (Integer) |
|
Yscale2 | Ordinate scaling factor for
function fct_ID3. (Real) |
, or |
Xscale2 | Abscissa scaling factor for
function fct_ID3. (Real) |
Comments
- The retractor is defined by 1 spring seatbelt element initially connected to the retractor and the node node_ID used to define the position of the retractor. The element El_ID must have a node initially at the same location as node node_ID. node_ID must not be a node of the seatbelt element.
- Seatbelt spring elements can be initially positioned inside the retractors in order to be released during the run. These elements are automatically detected and deactivated until they are released from the retractor. This part of the seatbelt must be connected to element El_ID and the nodes of these elements must be at the same location as node node_ID.
- The initial retractor force can either be defined by Yscale1 if fct_ID1=0 or by the 1st point of the fct_ID1(x=0) * Yscale1.
- When the retractor is unlocked, reference length of the element in the retractor is adjusted in order to ensure a constant force applied on the retractor.
- When the element size
in the retractor reaches Elem_size, a new element is
released. In case there are no more elements to release, the last element in
the retractor can continue to grow.
Figure 1. - The retractor is locked when the amount of seatbelt released reaches Pull_Lock value after the sensor sens_ID1 activation.
- When the retractor is
locked, the force applied on the retractor is defined by fct_ID1 and fct_ID2. The force versus pullout is:
- For loading:
(1) - For unloading:
(2)
- For loading:
- The retractor can
also act as a pretensioner when sensor sens_ID2 is activated. The retractor applies force to pull the seatbelt inside the retractor:
- If Typ_pre = 1: The function fct_ID3 defines the length of seatbelt pulled in as a function of time. In order to ensure that the effort on the seatbelt is not too high, the pretension is deactivated when the force in the retractor reaches Fmax.
(3) - If Typ_pre = 2: The function fct_ID3 defines the pull-in force as a function of time. The total force in the element is the sum of maximum of the retractor force and the pretension force defined by fct_ID3.
(4) - If Typ_pre = 3:
The total force in the element is the same as Typ_pre = 2, but the seatbelt will be release by the value Pull_Lock before the retractor gets locked.
- If Typ_pre = 4: The function fct_ID3 defines the pull-in force as a function of time. The total force in the element is the sum of the retractor force and the pretention force define by fct_ID3
(5) - If Typ_pre = 5: The function fct_ID3 defines the pull-in energy as a function of time. Fmax can be defined to ensure the effort in the element is not too high and the pretension is deactivated when Fmax is reached. The pull-in energy being defined by:
(6) - When the pretension is deactivated, the retractor is also locked.
The abscissa of the fct_ID1 and fct_ID2 is shifted in order to start at the pretension deactivation force
value.
Figure 2.
- If Typ_pre = 1:
- When a spring seatbelt element is in the retractor, viscosity is deactivated.
- When a spring
element is connected to a retractor its reference length
is modified. In order to
prevent the stiffness becoming infinite and the time step being too small in
case of pull-in, a maximum value is used for the stiffness, computed from
defined in seatbelt
material.
(7)