Class SpringNonLinear1

Represents a non-linear spring attached between two MassObjects, generates a Force which depends on how the SpringNonLinear1 is stretched. Damping is proportional to the relative velocity of the two objects.

The force equation is:

f(x) = S(6*Math.pow(x,-1) - Math.pow(x/2, -3))
x = distance between masses
S = resisting force constant

The potential energy is the integral of the force:

PE(x) = S(6 * Math.log(x) + 4*Math.pow(x, -2))

The minimum PE occurs where the force is zero:

S(6*Math.pow(x,-1) = Math.pow(x/2, -3))
6/x = 8 x^-3
3/4 = x^-2
x_min = sqrt(4/3) = 2/sqrt(3)

We subtract the minimum PE from the reported PE so that PE is zero at it's minimum.

To attach one end to a fixed point you can attach to an infinite mass MassObject or a Scrim.

Hierarchy (view full)

Spring
- SpringNonLinear1

Implements

Constructors

constructor

new SpringNonLinear1(name, body1, attach1_body, body2, attach2_body, restLength, stiffness?): SpringNonLinear1
Parameters
- name: string
  language-independent name of this object
- body1: MassObject
  body to attach to start point of the SpringNonLinear1
- attach1_body: GenericVector
  attachment point in body coords of body1
- body2: MassObject
  body to attach to end point of the SpringNonLinear1
- attach2_body: GenericVector
  attachment point in body coords of body2
- restLength: number
  length of spring when it has no force
- Optional stiffness: number
  amount of force per unit distance of stretch
Returns SpringNonLinear1
Overrides Spring.constructor
- Defined in sims/springs/SpringNonLinear1.ts:70

Properties

minPE_

minPE_: number = 0

minimum potential energy

`Static` ID

ID: number = 1

Counter used for naming SimObjects.

Methods

calcMinPE

calcMinPE(): void
Calculate minimum potential energy.

Returns void
- Defined in sims/springs/SpringNonLinear1.ts:135

calculateForces

calculateForces(): Force[]
Returns a list of Forces generated by this ForceLaw.

Returns Force[]
list of forces generated by this ForceLaw.
Implementation of ForceLaw.calculateForces
Overrides Spring.calculateForces
- Defined in sims/springs/SpringNonLinear1.ts:82

disconnect

disconnect(): void
Ensures this ForceLaw is not connected to anything and so can be garbage collected. For example, if this ForceLaw is an Observer, this will stop observing its Subject.

Returns void
Implementation of ForceLaw.disconnect
Inherited from Spring.disconnect
- Defined in lab/model/Spring.ts:134

getAttach1

getAttach1(): Vector
Returns attachment point for body 1, in body coordinates of body 1.

Returns Vector
attachment point for body 1, in body coordinates of body 1.
Inherited from Spring.getAttach1
- Defined in lab/model/Spring.ts:140

getAttach2

getAttach2(): Vector
Returns attachment point for body 2, in body coordinates of body 2.

Returns Vector
attachment point for body 2, in body coordinates of body 2.
Inherited from Spring.getAttach2
- Defined in lab/model/Spring.ts:147

getBodies

getBodies(): MassObject[]
Returns list of MassObjects being affected by this ForceLaw.

Returns MassObject[]
list of MassObjects being affected by this ForceLaw
Implementation of ForceLaw.getBodies
Inherited from Spring.getBodies
- Defined in lab/model/Spring.ts:152

getBody1

getBody1(): MassObject
Returns the RigidBody that start point of the spring is attached to.

Returns MassObject
the RigidBody that start point of the spring is attached to.
Inherited from Spring.getBody1
- Defined in lab/model/Spring.ts:159

getBody2

getBody2(): MassObject
Returns the RigidBody that end point of the spring is attached to.

Returns MassObject
the RigidBody that end point of the spring is attached to.
Inherited from Spring.getBody2
- Defined in lab/model/Spring.ts:166

getBoundsWorld

getBoundsWorld(): DoubleRect
Returns a rectangle that contains this SimObject in world coordinates.

Returns DoubleRect
rectangle that contains this SimObject in world coordinates
Implementation of Line.getBoundsWorld
Inherited from Spring.getBoundsWorld
- Defined in lab/model/Spring.ts:171

getChanged

getChanged(): boolean
Returns whether this SimObject has changed, and sets the state to "unchanged".

Returns boolean
whether this SimObject has changed
Implementation of Line.getChanged
Inherited from Spring.getChanged
- Defined in lab/model/SimObject.ts:160

getClassName

getClassName(): string
Returns name of class of this object.

Returns string
name of class of this object.
Overrides Spring.getClassName
- Defined in sims/springs/SpringNonLinear1.ts:77

getDamping

getDamping(): number
Returns the amount of damping for this spring. Damping is proportional to the relative velocity of the two points.

Returns number
amount of damping for this spring
Inherited from Spring.getDamping
- Defined in lab/model/Spring.ts:179

getEndPoint

getEndPoint(): Vector
Returns ending point of this line in world coords.

Returns Vector
ending point of this line in world coords.
Implementation of Line.getEndPoint
Inherited from Spring.getEndPoint
- Defined in lab/model/Spring.ts:184

getExpireTime

getExpireTime(): number
Returns the expiration time, when this SimObject should be removed from the SimList. This is intended for temporary SimObjects that illustrate, for example, contact forces or collisions.

Returns number
the expiration time, in time frame of the Simulation clock
Implementation of Line.getExpireTime
Inherited from Spring.getExpireTime
- Defined in lab/model/SimObject.ts:175

getLength

getLength(): number
Returns the distance between start and end points of this spring

Returns number
the distance between start and end points of this spring
Inherited from Spring.getLength
- Defined in lab/model/Spring.ts:211

getName

getName(opt_localized?): string
Name of this SimObject, either the language-independent name for scripting purposes or the localized name for display to user.

The language-independent name should be the same as the English version but capitalized and with spaces and dashes replaced by underscore, see Util.toName, nameEquals.

The name should give an idea of the role of the SimObject in the simulation. This allows us to to treat an object in a special way depending on its name. For example, we might use the name to decide what type of DisplayObject to create to represent the SimObject.
Parameters
- Optional opt_localized: boolean
  true means return the localized version of the name; default is false which means return the language independent name.
Returns string
name of this SimObject
Implementation of Line.getName
Inherited from Spring.getName
- Defined in lab/model/SimObject.ts:180

getPotentialEnergy

getPotentialEnergy(): number
Returns the potential energy due to this ForceLaw.

Returns number
the potential energy due to this ForceLaw
Implementation of ForceLaw.getPotentialEnergy
Overrides Spring.getPotentialEnergy
- Defined in sims/springs/SpringNonLinear1.ts:112

getRestLength

getRestLength(): number
Returns the length of this spring when no force is applied.

Returns number
rest length of this spring
Inherited from Spring.getRestLength
- Defined in lab/model/Spring.ts:225

getStartPoint

getStartPoint(): Vector
Returns starting point of this line in world coords

Returns Vector
starting point of this line in world coords.
Implementation of Line.getStartPoint
Inherited from Spring.getStartPoint
- Defined in lab/model/Spring.ts:230

getStiffness

getStiffness(): number
Returns stiffness of this spring.

Returns number
stiffness of this spring.
Inherited from Spring.getStiffness
- Defined in lab/model/Spring.ts:239

getStretch

getStretch(): number
Positive stretch means the spring is expanded, negative stretch means compressed.

Returns number
the amount that this line is stretched from its rest length
Inherited from Spring.getStretch
- Defined in lab/model/Spring.ts:246

getVector

getVector(): Vector
Returns the Vector from starting point to ending point.

Returns Vector
the Vector from starting point to ending point.
Implementation of Line.getVector
Inherited from Spring.getVector
- Defined in lab/model/Spring.ts:251

isMassObject

isMassObject(): boolean
Whether this implements the MassObject interface.

Returns boolean
Whether this implements the MassObject interface.
Implementation of Line.isMassObject
Inherited from Spring.isMassObject
- Defined in lab/model/SimObject.ts:185

minPELen

minPELen(): number
Returns length of spring that has minimum potential energy.

Returns number
length of spring that has minimum potential energy
- Defined in sims/springs/SpringNonLinear1.ts:129

nameEquals

nameEquals(name): boolean
Whether this SimObject has the given name, adjusting for transformation to the language-independent form of the name, as is done by Util.toName.
Parameters
- name: string
  the English or language-independent version of the name
Returns boolean
whether this SimObject has the given name (adjusted to language-independent form)
Implementation of Line.nameEquals
Inherited from Spring.nameEquals
- Defined in lab/model/SimObject.ts:190

potentialEnergy

potentialEnergy(len): number
Returns potential energy for a given length of spring.
Parameters
- len: number
  length of spring
Returns number
potential energy
- Defined in sims/springs/SpringNonLinear1.ts:121

setChanged

setChanged(): void
Marks that this SimObject has changed.

Returns void
Implementation of Line.setChanged
Inherited from Spring.setChanged
- Defined in lab/model/SimObject.ts:195

setDamping

setDamping(damping): Spring
Sets the value of damping for this spring. Damping is proportional to the relative velocity of the two points.
Parameters
- damping: number
  the value of damping for this spring
Returns Spring
this Spring to allow chaining of setters
Inherited from Spring.setDamping
- Defined in lab/model/Spring.ts:260

setExpireTime

setExpireTime(time): void
Sets the expiration time, when this SimObject should be removed from the SimList. This is intended for temporary SimObjects that illustrate, for example, contact forces or collisions.
Parameters
- time: number
  the expiration time, in time frame of the Simulation clock
Returns void
Implementation of Line.setExpireTime
Inherited from Spring.setExpireTime
- Defined in lab/model/SimObject.ts:200

setRestLength

setRestLength(value): void
Sets the rest length of this spring, which is used for calculating the stretch. When length of spring is the rest length, then no force is applied at either end.
Parameters
- value: number
  the rest length of this spring
Returns void
Inherited from Spring.setRestLength
- Defined in lab/model/Spring.ts:270

setStiffness

setStiffness(stiffness): void
Sets stiffness of this spring
Parameters
- stiffness: number
  the stiffness of this spring
Returns void
Inherited from Spring.setStiffness
- Defined in lab/model/Spring.ts:278

similar

similar(obj, _opt_tolerance?): boolean
Returns true if the given SimObject is similar to this SimObject for display purposes. SimObjects are similar when they are the same type and nearly the same size and location. Mainly used when showing forces - to avoid adding too many objects to the display. See SimList.getSimilar.
Parameters
- obj: SimObject
  the SimObject to compare to
- Optional _opt_tolerance: number
  the amount the object components can differ by
Returns boolean
true if this SimObject is similar to obj for display purposes
Implementation of Line.similar
Inherited from Spring.similar
- Defined in lab/model/SimObject.ts:205

toString

toString(): string
Returns string
Inherit Doc
Inherited from Spring.toString
- Defined in lab/model/Spring.ts:82

toStringShort

toStringShort(): string
Returns a minimal string representation of this object, usually giving just identity information like the class name and name of the object.

For an object whose main purpose is to represent another Printable object, it is recommended to include the result of calling toStringShort on that other object. For example, calling toStringShort() on a DisplayShape might return something like this:
```
DisplayShape{polygon:Polygon{'chain3'}}
```
Returns string
a minimal string representation of this object.
Implementation of ForceLaw.toStringShort
Inherited from Spring.toStringShort
- Defined in lab/model/SimObject.ts:152

Class SpringNonLinear1

Hierarchy (view full)

Implements

Index

Constructors

Properties

Methods

Constructors

constructor

Parameters

name: string

body1: MassObject

attach1_body: GenericVector

body2: MassObject

attach2_body: GenericVector

restLength: number

Optional stiffness: number

Returns SpringNonLinear1

Properties

minPE_

Static ID

Methods

calcMinPE

Returns void

calculateForces

Returns Force[]

disconnect

Returns void

getAttach1

Returns Vector

getAttach2

Returns Vector

getBodies

Returns MassObject[]

getBody1

Returns MassObject

getBody2

Returns MassObject

getBoundsWorld

Returns DoubleRect

getChanged

Returns boolean

getClassName

Returns string

getDamping

Returns number

getEndPoint

Returns Vector

getExpireTime

Returns number

getLength

Returns number

getName

Parameters

Optional opt_localized: boolean

Returns string

getPotentialEnergy

Returns number

getRestLength

Returns number

getStartPoint

Returns Vector

getStiffness

Returns number

getStretch

Returns number

getVector

Returns Vector

isMassObject

Returns boolean

minPELen

Returns number

nameEquals

Parameters

name: string

Returns boolean

potentialEnergy

Parameters

len: number

Returns number

`Optional` stiffness: number

`Static` ID

`Optional` opt_localized: boolean

`Optional` _opt_tolerance: number