# SpringDamper

Model ElementSpringDamper defines a spring damper acting between two markers.

SpringDamper

## Description

The element can be translational (applies a force) or rotational (applies a torque). In both cases, the force is characterized by a stiffness coefficient, a damping coefficient, a free-length, and a preload.

## Usage

# Translational Spring-Damper
SpringDamper (type="TRANSLATION", i=objMarker, j=objMarker, optional_attributes)

# Rotational Spring-Damper
SpringDamper (type="ROTATION", i=objMarker, j=objMarker, optional_attributes)

## Attribute Summary

Name Property Modifiable by command? Designable?
id Int ()
label Str ()
i Reference (Marker) Yes Yes
j Reference (Marker) Yes Yes
type Enum ("TRANSLATION ROTATION")
c Double () Yes Yes
ct Double () Yes Yes
k Double () Yes Yes
kt Double () Yes Yes
force Double () Yes Yes
torque Double () Yes Yes
length Double () Yes Yes
angle Double () Yes Yes
active Bool () Yes

## Attributes

Translational Spring Damper
type
String
Specifies the type of SPRINGDAMPER. Set type= "TRANSLATION". "TRANSLATION" implies that the element applies a force between the two Markers. No torque is applied.
The type attribute is mandatory.
i
Reference to an existing Marker object.
Specifies the marker at which the force or torque is applied. This is designated as the point of application of the force.
The i attribute is mandatory.
j
Reference to an existing Marker object.
Specifies the marker at which the reaction force and torque is applied. This is designated as the point of reaction of the force.
The j attribute is mandatory.
k
Double
Specifies the translational spring stiffness. This has units of force/unit translational deflection.
The k attribute is optional. When not specified, it defaults to 0.0.
k ≥ 0.0
c
Double
Specifies the translational damping coefficient. This has units of force/unit translational deflection velocity.
The c attribute is optional. When not specified, it defaults to 0.0.
c ≥ 0.0
length
Double
Specifies the free length of the spring.
The length attribute is optional. When not specified, it defaults to 0.0.
force
Double
Specifies the pre-load in the SPRINGDAMPER.
This is the force when the distance between the I and J markers is equal to the value specified by length. A positive value implies a force that tends to increase the distance. Conversely, a negative value tends to stretch the spring.
The force attribute is optional. When not specified, it defaults to 0.0.
Rotational Spring Damper
type
Specifies the type of SPRINGDAMPER. Set type= "ROTATION". "ROTATION" implies that the element applies a torque between the two markers. No force is applied.
i
Reference to an existing Marker object.
Specifies the marker at which the force or torque is applied. This is designated as the point of application of the force.
The i attribute is mandatory.
j
Reference to an existing Marker object.
Specifies the marker at which the reaction force and torque is applied. This is designated as the point of reaction of the force.
The j attribute is mandatory.
kt
Double
Specifies the rotational spring stiffness. This has units of torque/unit rotational deflection.
The kt attribute is optional. When not specified, it defaults to 0.0.
ct
Double
Specifies the rotational damping coefficient. This has units of torque/unit angular deflection velocity.
The ct attribute is optional. When not specified, it defaults to 0.0.
angle
Double
Specifies the free angle of the spring.
The angle attribute is optional. When not specified, it defaults to 0.0.
torque
Double
Specifies the pre-load in the SPRINGDAMPER.
This is the torque when the angle between the I and J markers is equal to the value specified by angle. A positive value implies a torque that tends to increase the angle (repulsive). Conversely, a negative values implies a torque that tends to "close" the angle.
The torque attribute is optional. When not specified, it defaults to 0.0.
Optional attributes - Available to all variants
id
Integer
Specifies the element identification number. This number must be unique among all the SpringDamper objects in the model.
This attribute is optional. MotionSolve will automatically create an ID when one is not specified.
Range of values: id > 0
label
String
Specifies the name of the SpringDamper object.
This attribute is optional. When not specified, MotionSolve will create a label for you.
active
Bool
Select one from True or False.
• True indicates that the element is active in the model and it affects the behavior of the system
• False indicates that the element is inactive in the model and it does not affect the behavior of the system. It is almost as if the entity was removed from the model, of course with the exception that can be turned "ON" when desirable.
The attribute active is optional. When not specified, active defaults to True.

## Examples

1. Model the translational SPRINGDAMPER in the XML examples section.
#< Force_SpringDamper
#     id                   = "18"
#     i_marker_id          = "22"
#     j_marker_id          = "11"
#     type                 = "TRANSLATIONAL"
#     stiffness            = "1200"
#     damping              = "10"
#     length               = "0.5"
#     preload              = "300"
#/>

spdp1 = SpringDamper (label="spdp1", i=m22, j=m11, type="TRANSLATION", c=10, k=1200, force=300, length=0.5)
2. Model the rotational SPRINGDAMPER in the XML examples section.
#<Force_SpringDamper
#     id                   = "18"
#     i_marker_id          = "1029"
#     j_marker_id          = "1039"
#     type                 = "ROTATIONAL"
#     stiffness            = "500"
#     damping              = "50"
#     length               = "0.3"
#     preload              = "0."
#/>

spdp2 = SpringDamper (label="spdp2", i=m1029, j=m1039, type="ROTATION", ct=50, kt=500, angle=0.3)