/PROP/TYPE4 (SPRING)
Block Format Keyword Defines spring property with one translational DOF. This spring accounts for nonlinear stiffness, damping and different unloading. Deformation based failure criteria is available.
Format
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
/PROP/TYPE4/prop_ID/unit_ID or /PROP/SPRING/prop_ID/unit_ID | |||||||||
prop_title | |||||||||
Mass | sens_ID | Isflag | Ileng | ||||||
K1 | C1 | A1 | B1 | D1 | |||||
fct_ID11 | H1 | fct_ID21 | fct_ID31 | fct_ID41 | |||||
F1 | E1 | Ascale1 | Hscale1 |
Definition
Field | Contents | SI Unit Example |
---|---|---|
prop_ID | Property
identifier. (Integer, maximum 10 digits) |
|
unit_ID | Unit Identifier. (Integer, maximum 10 digits) |
|
prop_title | Property
title. (Character, maximum 100 characters) |
|
Mass | Mass.
(Real) |
|
sens_ID | Sensor identifier used for
spring activation or deactivation.
(Integer) |
|
Isflag | Sensor flag. 2
(Integer) |
|
Ileng | Input per unit length flag.
(Integer) |
|
K1 | If
: Linear loading and unloading
stiffness. If : Only used as unloading stiffness for elasto-plastic springs. (Real) |
|
C1 | Damping. (Real) |
|
A1 | Nonlinear stiffness
function scale factor. Default = 1.0 (Real) |
|
B1 | Logarithmic rate effects
scale factor. (Real) |
|
D1 | Logarithmic rate effects
scale factor. Default = 1.0 (Real) |
|
fct_ID11 | Function identifier
defining
. 4
If H1 =4: Function defines upper yield curve. If H1 =8: Function is mandatory and defines the force versus spring length. (Integer) |
|
H1 | Spring Hardening flag for
nonlinear spring.
(Integer) |
|
fct_ID21 | Function identifier
defining force as a function of spring velocity,
. (Integer) |
|
fct_ID31 | Function identifier. If H1 =4: Defines lower yield curve If H1 =5: Defines residual displacement versus maximum displacement If H1 =6: Defines nonlinear unloading curve If H1 =7: Defines nonlinear unloading curve (Integer) |
|
fct_ID41 | Function identifier for
nonlinear damping
. (Integer) |
|
Negative failure
displacement. Default = -1030 (Real) |
||
Positive failure
displacement. Default = 1030 (Real) |
||
F1 | Abscissa scale factor for
damping functions for
and
. Default = 1.0 (Real) |
|
E1 | Ordinate scale factor for
the damping function
. (Real) |
|
Ascale1 | Abscissa scale factor for
the stiffness function
. Default = 1.0 (Real) |
|
Hscale1 | Ordinate scale factor for
the damping function
. Default = 1.0 (Real) |
Example (Seatbelt)
#RADIOSS STARTER
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/UNIT/2
unit for prop
kg mm ms
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/SPRING/2/2
Seatbelt
# M sensor_ID Isflag Ileng
5E-5 0 0 1
# K1 C1 A1 B1 D1
0.001 0 0 0 0
# fct_ID11 H1 fct_ID21 fct_ID31 fct_ID41 delta_min delta_max
1 2 0 0 0 0
# F1 E1 Ascale1 Hscale1
0 0 0 0
/MOVE_FUNCT/1
Seatbelt
# Ascale_x Fscale_y Ashift_x Fshift_y
0.001
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FUNCT/1
Seatbelt loading force vs engineering strain
# X Y
0. 0.
0.005 700.
0.02 3100.
0.03 5500.
0.15 17000.
1000. 17000.
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#ENDDATA
Comments
- The spring has one translational degree of freedom in the local x direction which is defined between node N1 and N2 of the spring.
- Spring is activated
and/or deactivated by sensor defined in sens_ID and depends on Isflag:
- If Isflag = 0, the spring element is activated by the sens_ID and cannot be deactivated. The initial length of the spring is based on the spring length at time=0.
- If Isflag = 1, the spring element is deactivated by the sens_ID and cannot be activated. The initial length of the spring is based on the spring length at time=0.
- If Isflag = 2, the spring is activated and/or deactivated by sens_ID and can switch activation state multiple times. If sensor is activated, the spring is active; if sensor is deactivated, spring is deactivated. The spring initial length, , is the distance between spring nodes at the time of sensor activation.
- If Ileng = 1, the
spring properties are based on the initial spring length. The input should be
entered as:Each spring will then have the following properties in the model:Where,
- , and
- Spring values entered in the spring property fields
- , and
- Spring’s actual physical mass, stiffness and damping
- Initial spring length which is the distance between node N1 and N2 of the spring
- Failure values entered as engineering strain
- Force computation. For
additional information, refer to Stiffness Formulation in
the User Guide.
- If Ileng =0, the value of
force
in the spring is computed as:For H1 = 1,2,4,5,6,7:
(1)
Where, is the difference between the current length and the initial length of the spring element.
with
If H1 = 8:(2) Where, and
If Ileng = 1, the value of force in the spring is computed as:(3) Where,- Engineering strain
- Nonlinear stiffness is a function of engineering strain
- Damping is a function of engineering strain rate
- If Ileng =0, the value of
force
in the spring is computed as:
- If H1 > 0 and fct_ID11 = 0, .