artisynth.core.materials

Class LinearElasticContact

java.lang.Object

artisynth.core.materials.MaterialBase

artisynth.core.materials.ContactForceBehavior

artisynth.core.materials.ElasticContactBase

artisynth.core.materials.LinearElasticContact

All Implemented Interfaces:

HasMaterialState, PostScannable, ScalableUnits, java.lang.Cloneable, CompositeProperty, HasProperties, Clonable, Scannable

public class LinearElasticContact
extends ElasticContactBase

Implementation of non-linear elastic foundation compliance model from: Bei, Y. and Fregly, B. J. (2004). Multibody dynamic simulation of knee contact mechanics. Medical engineering and physics, 26(9), 777-789.

Author:

stavness

Nested Class Summary

Nested classes/interfaces inherited from class artisynth.core.materials.ElasticContactBase

ElasticContactBase.DampingMethod

Field Summary

Fields

Modifier and Type	Field and Description
static FieldPropertyList	myProps

Fields inherited from class artisynth.core.materials.ContactForceBehavior

TWO_WAY_CONTACT

Constructor Summary

Constructors

Constructor and Description
LinearElasticContact() Need no-args constructor for scanning
LinearElasticContact(double youngsModulus, double poissonsRatio, double dampingFactor, double thickness) Constructs a new LinearElasticContact material with specified properties.

Method Summary

Modifier and Type	Method and Description
LinearElasticContact	clone() Returns a clone of this composite property.
void	computeResponse(double[] fres, double dist, ContactPoint cpnt0, ContactPoint cpnt1, Vector3d normal, double contactArea, int flags) Computes the force response for a given contact.
FieldPropertyList	getAllPropertyInfo() Returns a list giving static information about all properties exported by this object.
double	getPoissonsRatio() Queries Poisson's ratio for this material.
double	getYoungsModulus() Queries Young's modulus for this material.
ScalarFieldComponent	getYoungsModulusField() Queries the field, if any, associated with Young's modulus.
void	setPoissonsRatio(double nu) Sets Poisson's ratio for this material.
void	setYoungsModulus(double E) Sets Young's modulus for this material.
void	setYoungsModulusField(ScalarFieldComponent field) Binds Young's modulus to a field, or unbinds it if field is null.

Methods inherited from class artisynth.core.materials.ElasticContactBase

getDampingFactor, getDampingMethod, getMinThicknessRatio, getThickness, getThicknessField, getUseLocalContactArea, getUseLogDistance, setDampingFactor, setDampingMethod, setMinThicknessRatio, setThickness, setThicknessField, setUseLocalContactArea, setUseLogDistance, writeItems

Methods inherited from class artisynth.core.materials.ContactForceBehavior

computeContactArea, getSubClasses, registerSubclass

Methods inherited from class artisynth.core.materials.MaterialBase

advanceState, createStateObject, getProperty, getPropertyHost, getPropertyInfo, hasProperty, hasState, hasSymmetricTangent, isWritable, postscan, scaleDistance, scaleMass, scan, setPropertyHost, setPropertyInfo, symmetryOrStateChanged, updateMaterial, write

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

myProps

public static FieldPropertyList myProps

Constructor Detail

LinearElasticContact

public LinearElasticContact()

Need no-args constructor for scanning

LinearElasticContact

public LinearElasticContact(double youngsModulus,
                            double poissonsRatio,
                            double dampingFactor,
                            double thickness)

Constructs a new LinearElasticContact material with specified properties.

Parameters:

youngsModulus - Young's modulus (the "stiffness")

poissonsRatio - Poissons ratio

dampingFactor - multiplier for damping forces

thickness - thickness of the foundation layer

Method Detail

getAllPropertyInfo

public FieldPropertyList getAllPropertyInfo()

Description copied from interface: HasProperties

Returns a list giving static information about all properties exported by this object.

Specified by:

getAllPropertyInfo in interface HasProperties

Overrides:

getAllPropertyInfo in class ElasticContactBase

Returns:

static information for all exported properties

computeResponse

public void computeResponse(double[] fres,
                            double dist,
                            ContactPoint cpnt0,
                            ContactPoint cpnt1,
                            Vector3d normal,
                            double contactArea,
                            int flags)

Computes the force response for a given contact. The response consists of three values: force, compliance, and damping, all of which should be placed into fres. The force is defined as the restoring force

 force = f(dist)
 

computed in response to the interpenetration distance dist. Note that in general, dist will be negative, and a negative force will be expected in response. The compliance is the reciprocal of the derivative of f(dist) evaluated at dist. The damping is a positive damping parameter used to generate damping forces in response to motion in the contact direction.

Other information the can be used includes the two contact points associated the contact, and the contact normal, which is facing outward from the contact surface.

Specified by:

computeResponse in class ContactForceBehavior

Parameters:

fres - returns the force, compliance and damping for a given contact distance.

dist - contact interpenetration distance. This value is usually negative, with greater negativity indicating greater interpenetration.

cpnt0 - first contact point

cpnt1 - second contact point

normal - contact normal, directed from cpnt0 to cpnt1

contactArea - average area associated with the contact, or -1 if this information is not available

flags - flags providing additional information to the calculation. These include ContactForceBehavior.TWO_WAY_CONTACT, which indicates two-way vertex penetration contact.

getPoissonsRatio

public double getPoissonsRatio()

Queries Poisson's ratio for this material.

Returns:

Poission's ratio

setPoissonsRatio

public void setPoissonsRatio(double nu)

Sets Poisson's ratio for this material.

Parameters:

nu - new value of Poission's ratio

getYoungsModulus

public double getYoungsModulus()

Queries Young's modulus for this material.

Returns:

Young's modulus

setYoungsModulus

public void setYoungsModulus(double E)

Sets Young's modulus for this material.

Parameters:

E - new value for Young's modulus

getYoungsModulusField

public ScalarFieldComponent getYoungsModulusField()

Queries the field, if any, associated with Young's modulus.

Returns:

Young's modulus field, or null

setYoungsModulusField

public void setYoungsModulusField(ScalarFieldComponent field)

Binds Young's modulus to a field, or unbinds it if field is null.

Parameters:

field - field to bind to, or null

clone

public LinearElasticContact clone()

Returns a clone of this composite property.

Specified by:

clone in interface CompositeProperty

Specified by:

clone in interface Clonable

Overrides:

clone in class ElasticContactBase

Returns:

clone of this property