Contact

Contact#

Numba implementation module containing contact between rods and rigid bodies and other rods rigid bodies or surfaces.

Description#

Available Contact Classes

`NoContact`	This is the base class for contact applied between rod-like objects and allowed contact objects.
`RodRodContact`	This class is for applying contact forces between rod-rod.
`RodCylinderContact`	This class is for applying contact forces between rod-cylinder.
`RodSelfContact`	This class is modeling self contact of rod.
`RodSphereContact`	This class is for applying contact forces between rod-sphere.
`RodPlaneContact`	This class is for applying contact forces between rod-plane.
`RodPlaneContactWithAnisotropicFriction`	This class is for applying contact forces between rod-plane with friction.
`CylinderPlaneContact`	This class is for applying contact forces between cylinder-plane.

Built-in Contact Classes#

class elastica.contact_forces.NoContact[source]#

This is the base class for contact applied between rod-like objects and allowed contact objects.

Notes

Every new contact class must be derived from NoContact class.

__init__()[source]#: NoContact class does not need any input parameters.

apply_contact(system_one, system_two, time=np.float64(0.0))[source]#

Apply contact forces and torques between two system object..

In NoContact class, this routine simply passes.

Return type:

None

Parameters:

system_one
system_two

class elastica.contact_forces.RodRodContact(k, nu)[source]#

This class is for applying contact forces between rod-rod.

Examples

How to define contact between rod and rod.

>>> simulator.detect_contact_between(first_rod, second_rod).using(
...    RodRodContact,
...    k=1e4,
...    nu=10,
... )

__init__(k, nu)[source]#

Parameters:

kfloat: Contact spring constant.
nufloat: Contact damping constant.

apply_contact(system_one, system_two, time=np.float64(0.0))[source]#

Apply contact forces and torques between RodType object and RodType object.

Return type:

None

Parameters:

system_one: RodType
system_two: RodType

class elastica.contact_forces.RodCylinderContact(k, nu, velocity_damping_coefficient=0.0, friction_coefficient=0.0)[source]#

This class is for applying contact forces between rod-cylinder. If you are want to apply contact forces between rod and cylinder, first system is always rod and second system is always cylinder. In addition to the contact forces, user can define apply friction forces between rod and cylinder that are in contact. For details on friction model refer to this [1].

Notes

The velocity_damping_coefficient is set to a high value (e.g. 1e4) to minimize slip and simulate stiction (static friction), while friction_coefficient corresponds to the Coulombic friction coefficient.

Examples

How to define contact between rod and cylinder.

>>> simulator.detect_contact_between(rod, cylinder).using(
...    RodCylinderContact,
...    k=1e4,
...    nu=10,
... )

[1]

Preclik T., Popa Constantin., Rude U., Regularizing a Time-Stepping Method for Rigid Multibody Dynamics, Multibody Dynamics 2011, ECCOMAS. URL: https://www10.cs.fau.de/publications/papers/2011/Preclik_Multibody_Ext_Abstr.pdf

__init__(k, nu, velocity_damping_coefficient=0.0, friction_coefficient=0.0)[source]#

Parameters:

kfloat: Contact spring constant.
nufloat: Contact damping constant.
velocity_damping_coefficientfloat: Velocity damping coefficient between rigid-body and rod contact is used to apply friction force in the slip direction.
friction_coefficientfloat: For Coulombic friction coefficient for rigid-body and rod contact.

apply_contact(system_one, system_two, time=np.float64(0.0))[source]#

Apply contact forces and torques between two system object..

In NoContact class, this routine simply passes.

Return type:

None

Parameters:

system_one
system_two

class elastica.contact_forces.RodSelfContact(k, nu)[source]#

This class is modeling self contact of rod.

Examples

How to define contact rod self contact.

>>> simulator.detect_contact_between(rod, rod).using(
...    RodSelfContact,
...    k=1e4,
...    nu=10,
... )

__init__(k, nu)[source]#

Parameters:

kfloat: Contact spring constant.
nufloat: Contact damping constant.

apply_contact(system_one, system_two, time=np.float64(0.0))[source]#

Apply contact forces and torques between RodType object and itself.

Return type:

None

Parameters:

system_one: RodType
system_two: RodType

class elastica.contact_forces.RodSphereContact(k, nu, velocity_damping_coefficient=0.0, friction_coefficient=0.0)[source]#

This class is for applying contact forces between rod-sphere. First system is always rod and second system is always sphere. In addition to the contact forces, user can define apply friction forces between rod and sphere that are in contact. For details on friction model refer to this [1].

Notes

Examples

How to define contact between rod and sphere.

>>> simulator.detect_contact_between(rod, sphere).using(
...    RodSphereContact,
...    k=1e4,
...    nu=10,
... )

[1]

__init__(k, nu, velocity_damping_coefficient=0.0, friction_coefficient=0.0)[source]#

Parameters:

kfloat: Contact spring constant.
nufloat: Contact damping constant.
velocity_damping_coefficientfloat: Velocity damping coefficient between rigid-body and rod contact is used to apply friction force in the slip direction.
friction_coefficientfloat: For Coulombic friction coefficient for rigid-body and rod contact.

apply_contact(system_one, system_two, time=np.float64(0.0))[source]#

Apply contact forces and torques between RodType object and Sphere object.

Return type:

None

Parameters:

system_one: RodType
system_two: Sphere

class elastica.contact_forces.RodPlaneContact(k, nu)[source]#

This class is for applying contact forces between rod-plane. First system is always rod and second system is always plane. For more details regarding the contact module refer to Eqn 4.8 of Gazzola et al. RSoS (2018).

Examples

How to define contact between rod and plane.

>>> simulator.detect_contact_between(rod, plane).using(
...    RodPlaneContact,
...    k=1e4,
...    nu=10,
... )

__init__(k, nu)[source]#

Parameters:

kfloat: Contact spring constant.
nufloat: Contact damping constant.

apply_contact(system_one, system_two, time=np.float64(0.0))[source]#

Apply contact forces and torques between RodType object and Plane object.

Return type:

None

Parameters:

system_one: object: Rod object.
system_two: object: Plane object.

class elastica.contact_forces.RodPlaneContactWithAnisotropicFriction(k, nu, slip_velocity_tol, static_mu_array, kinetic_mu_array)[source]#

This class is for applying contact forces between rod-plane with friction. First system is always rod and second system is always plane. For more details regarding the contact module refer to Eqn 4.8 of Gazzola et al. RSoS (2018).

Examples

How to define contact between rod and plane.

>>> simulator.detect_contact_between(rod, plane).using(
...    RodPlaneContactWithAnisotropicFriction,
...    k=1e4,
...    nu=10,
...    slip_velocity_tol = 1e-4,
...    static_mu_array = np.array([0.0,0.0,0.0]),
...    kinetic_mu_array = np.array([1.0,2.0,3.0]),
... )

__init__(k, nu, slip_velocity_tol, static_mu_array, kinetic_mu_array)[source]#

Parameters:

kfloat: Contact spring constant.
nufloat: Contact damping constant.
slip_velocity_tol: float: Velocity tolerance to determine if the element is slipping or not.
static_mu_array: numpy.ndarray: 1D (3,) array containing data with ‘float’ type. [forward, backward, sideways] static friction coefficients.
kinetic_mu_array: numpy.ndarray: 1D (3,) array containing data with ‘float’ type. [forward, backward, sideways] kinetic friction coefficients.

apply_contact(system_one, system_two, time=np.float64(0.0))[source]#

Apply contact forces and torques between RodType object and Plane object with anisotropic friction.

Return type:

None

Parameters:

system_one: RodType
system_two: SurfaceType

class elastica.contact_forces.CylinderPlaneContact(k, nu)[source]#

This class is for applying contact forces between cylinder-plane. First system is always cylinder and second system is always plane. For more details regarding the contact module refer to Eqn 4.8 of Gazzola et al. RSoS (2018).

Examples

How to define contact between cylinder and plane.

>>> simulator.detect_contact_between(cylinder, plane).using(
...    CylinderPlaneContact,
...    k=1e4,
...    nu=10,
... )

__init__(k, nu)[source]#

Parameters:

kfloat: Contact spring constant.
nufloat: Contact damping constant.

apply_contact(system_one, system_two, time=np.float64(0.0))[source]#

This function computes the plane force response on the cylinder, in the case of contact. Contact model given in Eqn 4.8 Gazzola et. al. RSoS 2018 paper is used.

Return type:

None

Parameters:

system_one: Cylinder
system_two: SurfaceBase

Contact

Contents

Contact#

Description#

Built-in Contact Classes#