Torsional Spring-Damper

Rotating spring-damper connection with Coulomb friction, locking and rigid stops.

blockType: Engee1DMechanical.Elements.Rotational.SpringDamper

Path in the library:

/Physical Modeling/1D Mechanical/Couplings & Drives/Torsional Spring-Damper

Description

Block Torsional Spring-Damper It consists of a rotary spring and a damper that create a combination of internal torques between the two connected axes of the drive shaft, the rod and the housing. The unit determines the torque using the following characteristics:

Linear damping spring.
Coulomb friction (including blocking static friction).
Pliability with a hard stop.

This block is a composite component consisting of the following blocks:

Block	Contribution	Library
Loaded-Contact Rotational Friction	Coulomb friction	Physical Modeling/1D Mechanical/Brakes & Detents/Rotational
Rotational Damper	Dampening	Physical Modeling/Fundamental/Mechanical/Rotational/Elements
Rotational Spring	Spring
Rotational Hard Stop	Hard focus

Block

Contribution

Library

Loaded-Contact Rotational Friction

Coulomb friction

Physical Modeling/1D Mechanical/Brakes & Detents/Rotational

Rotational Damper

Dampening

Physical Modeling/Fundamental/Mechanical/Rotational/Elements

Rotational Spring

Spring

Rotational Hard Stop

Hard focus

Assumptions and limitations

Taking into account the rigid stop and Coulomb friction increases the accuracy of the model, but reduces the simulation speed.

Ports

Conserving

# R — base surface port
rotational mechanics

Details

A mechanical rotary port connected to the rod.

Program usage name

rod_flange

# C — port of the driven (movable) surface
rotational mechanics

Details

A mechanical rotary port connected to a shaft that moves between stops mounted on the housing.

Program usage name

case_flange

Parameters

Spring-Damper

Details

The stiffness of the rotary spring acting on the connected drive shafts.

Units	`Nm/rad` \| `mNm/rad` \| `kNm/rad` \| `kgfm/rad` \| `lbfft/rad` \| `Nm/deg` \| `mNm/deg` \| `kNm/deg` \| `kgfm/deg` \| `lbfft/deg` \| `Ws/rad` \| `HP_DIN/rpm` \| `HP_DINs/rad`
Default value	`1000.0 N*m/rad`
Program usage name	`k`
Evaluatable	Yes

# Viscous friction coefficient — coefficient of viscous friction of rotation
N*m/(rad/s) | ft*lbf/(rad/s)

Details

The coefficient of rotational friction acting on the connected drive shafts.

Units	`Nm/(rad/s)` \| `ftlbf/(rad/s)`
Default value	`10.0 N*m/(rad/s)`
Program usage name	`viscous_coefficient`
Evaluatable	Yes

# Coulomb friction torque — kinetic moment of friction
N*m | uN*m | mN*m | kN*m | MN*m | GN*m | kgf*m | lbf*in | lbf*ft

Details

A constant kinetic moment of friction acting on the connected drive shafts. This constant torque prevents rotation at any speed.

Units	`Nm` \| `uNm` \| `mNm` \| `kNm` \| `MNm` \| `GNm` \| `kgfm` \| `lbfin` \| `lbf*ft`
Default value	`0.0 N*m`
Program usage name	`T_coulomb`
Evaluatable	Yes

# Ratio of static to kinetic friction — the ratio of static and kinetic friction

Details

The constant value of the ratio of the static moment of Coulomb friction to the kinetic moment of Coulomb friction acting on the connected drive shafts. The value must be greater than or equal to one.

Default value	`1.1`
Program usage name	`static_to_kinetic_friction_torque_ratio`
Evaluatable	Yes

Details

The minimum relative angular velocity below which two connected drive shafts can lock and rotate together.

Units	`rad/s` \| `deg/s` \| `rad/min` \| `deg/min` \| `rpm` \| `rps`
Default value	`0.001 rad/s`
Program usage name	`w_slip_threshold`
Evaluatable	Yes

Hard Stops

# Hard stop — simulation of a rigid stop

Details

Turn on or off the torque during a hard stop:

Uncheck this option to increase the simulation speed by eliminating the torque during a hard stop.
Select this option to increase the accuracy of the simulation by turning on the torque during a hard stop.

Default value	`false (switched off)`
Program usage name	`enable_hardstop`
Evaluatable	Yes

# Upper bound — position of the upper boundary of the rigid stop
rad | deg | rev | mrad | arcsec | arcmin | gon

Details

The angular displacement of the upper boundary of the rigid stop from the reference angle of the torque reference. The value must be greater than the parameter value. Lower bound.

Dependencies

To use this option, check the box Hard stop.

Units	`rad` \| `deg` \| `rev` \| `mrad` \| `arcsec` \| `arcmin` \| `gon`
Default value	`10.0 deg`
Program usage name	`upper_bound`
Evaluatable	Yes

# Lower bound — position of the lower boundary of the rigid stop
rad | deg | rev | mrad | arcsec | arcmin | gon

Details

The angular displacement of the lower boundary of the rigid stop from the reference angle of the elastic force in the spring. The value must be less than the parameter value. Upper bound.

Dependencies

To use this option, check the box Hard stop.

Units	`rad` \| `deg` \| `rev` \| `mrad` \| `arcsec` \| `arcmin` \| `gon`
Default value	`-10.0 deg`
Program usage name	`lower_bound`
Evaluatable	Yes

# Hard stop model — choosing a hard stop model
Stiffness and damping applied smoothly through transition region, damped rebound | Full stiffness and damping applied at bounds, undamped rebound | Full stiffness and damping applied at bounds, damped rebound | Based on coefficient of restitution

Details

Stiffness and rebound parameters for the rigid limiter model. The composite implementation of the block uses Rotational Hard Stop. You can choose one of the following options:

Stiffness and damping applied smoothly through transition region, damped rebound;
Full stiffness and damping applied at bounds, undamped rebound;
Full stiffness and damping applied at bounds, damped rebound;
Based on coefficient of restitution.

Dependencies

To use this option, check the box Hard stop.

Values	`Stiffness and damping applied smoothly through transition region, damped rebound` \| `Full stiffness and damping applied at bounds, undamped rebound` \| `Full stiffness and damping applied at bounds, damped rebound` \| `Based on coefficient of restitution`
Default value	`Stiffness and damping applied smoothly through transition region, damped rebound`
Program usage name	`hard_stop_model`
Evaluatable	Yes

Details

The coefficient of elasticity of the rigid stop. This value is only applicable if the relative angle is within the stop area.

Dependencies

To use this option, check the box Hard stop.

Units	`Nm/rad` \| `mNm/rad` \| `kNm/rad` \| `kgfm/rad` \| `lbfft/rad` \| `Nm/deg` \| `mNm/deg` \| `kNm/deg` \| `kgfm/deg` \| `lbfft/deg` \| `Ws/rad` \| `HP_DIN/rpm` \| `HP_DINs/rad`
Default value	`1.0e6 N*m/rad`
Program usage name	`k_hard_stop`
Evaluatable	Yes

# Contact damping — the damping coefficient of the rigid stop
N*m/(rad/s) | ft*lbf/(rad/s)

Details

The damping coefficient of the rigid stop. This value is only applicable if the relative angle is within the stop area. The value must be greater than zero.

Dependencies

To use this option, check the box Hard stop.

Units	`Nm/(rad/s)` \| `ftlbf/(rad/s)`
Default value	`10.0 N*m/(rad/s)`
Program usage name	`C_hard_stop`
Evaluatable	Yes

# Transition region — the area of partial hard stop effect
rad | deg | rev | mrad | arcsec | arcmin | gon

Details

The distance from full compression or full stretching, where the effects of stiffness and damping are partially applied. If for the parameter Hard stop model value selected Stiffness and damping applied smoothly through transition region, damped rebound then the block smoothly transitions from stiffness and damping as the spring approaches full tension or full compression.

Dependencies

To use this option, check the box Hard stop, and for the parameter Hard stop model set the value Stiffness and damping applied smoothly through transition region, damped rebound.

Units	`rad` \| `deg` \| `rev` \| `mrad` \| `arcsec` \| `arcmin` \| `gon`
Default value	`0.001 rad`
Program usage name	`transition_region`
Evaluatable	Yes

# Coefficient of restitution — the ratio of the final and initial relative velocity between the shaft and the limiter after a collision

Details

The ratio of the final and initial relative velocity between the shaft and the limiter after the shaft rebounds.

Dependencies

To use this option, check the box Hard stop, and for the parameter Hard stop model set the value Based on coefficient of restitution.

Default value	`0.7`
Program usage name	`restitution_coefficient`
Evaluatable	Yes

Details

The threshold value of the relative velocity between the shaft and the limiter before the collision. If the shaft hits the housing at a speed lower than the value of this parameter, they remain in contact. Otherwise, the shaft bounces off. To avoid simulating static contact between the shaft and the housing, set this parameter to 0.

Dependencies

To use this option, check the box Hard stop, and for the parameter Hard stop model set the value Based on coefficient of restitution.

Units	`rad/s` \| `deg/s` \| `rad/min` \| `deg/min` \| `rpm` \| `rps`
Default value	`0.1 rad/s`
Program usage name	`w_static_contact_threshold`
Evaluatable	Yes

# Static contact release torque threshold — the threshold value of the torque required for the transition from the contact state to the free state
N*m | uN*m | mN*m | kN*m | MN*m | GN*m | kgf*m | lbf*in | lbf*ft

Details

The minimum value of the torque required to bring the shaft out of static contact.

Dependencies

To use this option, check the box Hard stop, and for the parameter Hard stop model set the value Based on coefficient of restitution.

Units	`Nm` \| `uNm` \| `mNm` \| `kNm` \| `MNm` \| `GNm` \| `kgfm` \| `lbfin` \| `lbf*ft`
Default value	`0.001 N*m`
Program usage name	`T_static_contact_release_threshold`
Evaluatable	Yes

Initial Conditions

# Initial deformation — the value of the initial deformation
rad | deg | rev | mrad | arcsec | arcmin | gon

Details

The initial deformation of the rotary spring relative to the reference angle of the torque reference.

Units	`rad` \| `deg` \| `rev` \| `mrad` \| `arcsec` \| `arcmin` \| `gon`
Default value	`0.0 deg`
Program usage name	`delta_phi_start`
Evaluatable	Yes