# simscape.multibody.AxialSpringDamper class

Package: simscape.multibody
Superclasses: `simscape.multibody.JointForceLaw`

Construct axial spring-damper force law

## Description

Use an object of the `simscape.multibody.AxialSpringDamper` class to construct an axial spring-damper force law. You can use the force law to apply a pure axial force to a `simscape.multibody.PrismaticPrimitive` object. The force is based on the current position and velocity of the primitive

$F=-{k}_{s}·\left(p-{p}_{0}\right)-{k}_{d}\stackrel{˙}{p}$,

where:

SymbolDescription
$F$Applied axial force
${p}_{0}$Equilibrium position of the spring
${k}_{s}$Spring stiffness
${k}_{d}$Damping coefficient
$p$Prismatic primitive position
$\stackrel{˙}{p}$Prismatic primitive velocity

### Class Attributes

 `Sealed` `true` `ConstructOnLoad` `true` `RestrictsSubclassing` `true`

For information on class attributes, see Class Attributes.

## Creation

### Description

`asd = simscape.multibody.AxialSpringDamper` constructs an axial spring-damper force law and sets the parameters to `simscape.Value` objects with a value of zero.

## Properties

expand all

Equilibrium position of the spring, specified as a `simscape.Value` object that represents a scalar with a unit of length. The scalar can be positive, negative, or zero. The axial spring force is zero when the primitive position is at the equilibrium position.

Example: `simscape.Value(1,"mm")`

#### Attributes:

 `GetAccess` `public` `SetAccess` `public` `NonCopyable` `true`

Stiffness of the spring, specified as a `simscape.Value` object that represents a scalar with a unit of force/length. The scalar is a measure of how hard the spring pushes the primitive position toward the equilibrium position and must be nonnegative.

Example: `simscape.Value(1,"N/m")`

#### Attributes:

 `GetAccess` `public` `SetAccess` `public` `NonCopyable` `true`

Damping coefficient of the damper, specified as a `simscape.Value` object that represents a scalar with a unit of force/linear velocity. The scalar is a measure of how hard the damper resists the motion of a primitive and must be nonnegative.

Example: `simscape.Value(1,"N/(m/s)")`

#### Attributes:

 `GetAccess` `public` `SetAccess` `public` `NonCopyable` `true`

## Version History

Introduced in R2022a