Double-Acting Actuator (IL)

A two-way linear actuator in an isothermal fluid network.

blockType: EngeeFluids.IsothermalLiquid.Actuators.TranslationalDoubleActing

Path in the library:

/Physical Modeling/Fluids/Isothermal Liquid/Actuators/Double-Acting Actuator (IL)

Description

Block Double-Acting Actuator (IL) It simulates a drive that converts the pressure difference between two chambers into a piston movement. The movement of the piston is controlled by a pressure drop on both sides of the plate separating the chambers of the block. The stroke limits of the piston are modeled by one of the rigid stop models. The compressibility of the liquid is additionally modeled in both chambers of the piston.

Ports A and B are inputs for the isothermal fluid. Port C is associated with the drive housing, port R is associated with the piston, and it returns the speed of the piston. The position of the piston is calculated inside the system and transmitted to port p.

The direction of movement of the piston is set by the parameter Mechanical orientation. If for the parameter Mechanical orientation the value is set Pressure at A causes positive displacement of R relative to C, then the piston is pushed out with a positive pressure drop - . If for the parameter Mechanical orientation the value is set Pressure at A causes negative displacement of R relative to C, then the piston retracts with a positive pressure difference between the chambers.

Moving

The movement of the piston is determined by the displacement of port R relative to port C. Parameter Value Mechanical orientation determines the direction of displacement of the piston. The movement of the piston is neutral (equal to 0), when the camera volume A is equal to Dead volume.

The hard limiter model

To avoid mechanical damage to the actuator in the extreme positions of the piston, the unit simulates the nonlinear position of the actuator when the piston approaches these limits. Block Double-Acting Actuator (IL) simulates this behavior using a choice of four rigid limiter models, in which limiters are considered as spring-damping systems. Rigid Limiter Models:

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.

In the extreme positions of the piston, a rigid limiter force arises, the range of which is within Transition region for Piston stroke or Initial piston displacement from chamber A cap. Outside of this area .

For more information about the models of the hard limiter, see the block page Translational Hard Stop..

The damper

The block can simulate shock absorption in the extreme positions of the piston. If the check box is selected Cylinder A end cushioning and/or Cylinder B end cushioning, then the block takes into account the deceleration of the piston as it approaches the maximum value of the stroke length of the piston, determined by the parameter Piston stroke. For more information about the hydraulic cylinder damper, see the section Cylinder Cushion (IL).

Friction

If the check box is selected Cylinder friction effect, then the block takes into account the friction of the piston during its movement, with the resulting friction being a combination of the effects of Strobeck, Coulomb, and viscosity. The unit measures the pressure difference between the pressure in the chamber and the ambient pressure. For more information about the friction model and its limitations, see the section Cylinder Friction (IL).

The leak

The block allows you to take into account possible leaks between cameras A and B. If the liquid is the same in both chambers (check the boxes Same fluid on both sides and Internal leakage), then a Poiseuille flow is modeled between the piston and the cylinder. For more information about leak modeling, see the section Laminar Leakage (IL).

where

— kinematic viscosity of the liquid;
— the length of the piston, p - ;
— port pressure A;
— port pressure B;
is the diameter of the cylinder, which can be written as , where — parameter value Piston-cylinder clearance;
— the diameter of the piston, which is calculated as , where — the average value of the parameters Piston cross-sectional area in chamber A and Piston cross-sectional area in chamber B.

Numerical smoothing of area and pressure values

The computational stability of the simulation is optionally regulated by the parameter Smoothing factor. If Smoothing factor If it is not equal to zero, then the value of the orifice area of the dampers A and B and the pressure range of the check valve are smoothed out. The hole area changes smoothly between the parameters Leakage area between plunger and cushion sleeve and Cushion plunger cross-sectional area. The valve pressure changes smoothly in the range between the parameters Check valve cracking pressure differential and Check valve maximum pressure differential.

Block diagram

Block Double-Acting Actuator (IL) It consists of four library blocks Isothermal fluid and two library blocks Mechanics:

Translational Hard Stop
Laminar Leakage (IL)
Translational Mechanical Converter (IL)
Absolute Translational Motion Sensor
Cylinder Cushion (IL)
Cylinder Friction (IL)

The structural diagram of the drive is shown in the diagram.

double acting actuator il 1

Conservation of momentum

The momentum conservation equation for the drive has the form:

where

— the force that the liquid exerts on the surface of the transducer. This value does not take into account the forces from the sub-components of the block: the rigid limiter (Translational Hard Stop), cylinder damper Cylinder Cushion (IL), friction in the cylinder Cylinder Friction (IL). To learn about the contribution of these forces to the converter surface, refer to the documentation pages for these sub-components.;
depends on the parameter value Mechanical orientation:
- If for the parameter Mechanical orientation the value is set Pressure at A causes positive displacement of R relative to C Then ;
- If for the parameter Mechanical orientation the value is set Pressure at A causes negative displacement of R relative to C Then ;
— the cross-sectional area of the stem opening, which can be calculated as ;
— parameter value Piston cross-sectional area in chamber A;
— parameter value Piston cross-sectional area in chamber B;
— pressure inside chamber A;
— pressure inside chamber B;
— ambient pressure.

Ports

Conserving

# A — inlet for fluid flow into the chamber A
isothermal liquid

Details

isothermal liquid port corresponding to the inlet to chamber A.

Program usage name

port_a

# B — inlet for fluid flow into the chamber B
isothermal liquid

Details

isothermal liquid port corresponding to the inlet to chamber B.

Program usage name

port_b

# R — actuator piston
translational mechanics

Details

A mechanical progressive port corresponding to the actuator piston.

Program usage name

rod_flange

# C — drive housing
translational mechanics

Details

Mechanical progressive port corresponding to the actuator housing.

Program usage name

case_flange

Output

# p — piston position
scalar

Details

Piston position in m.

Data types	`Float64`.
Complex numbers support	No

Parameters

Actuator

# Same fluid on both sides — is the same fluid simulated in both chambers of the unit

Details

Whether the same fluid is simulated on both sides of the block. If the option is checked, then the properties of the liquid are distributed through the block. If unchecked, the chambers of the unit are connected to isolated networks of liquids with different properties.

Default value	`true (switched on)`
Program usage name	`same_properties`
Evaluatable	No

# Mechanical orientation — the direction of movement of the piston
Pressure at A causes positive displacement of R relative to C | Pressure at A causes negative displacement of R relative to C

Details

Determines the direction of movement of the piston. Options to choose from:

Pressure at A causes positive displacement of R relative to C — the movement of the piston is positive if the volume of liquid in port A increases. This corresponds to the movement of the rod out of the cylinder.
Pressure at A causes negative displacement of R relative to C — the movement of the piston is negative if the volume of liquid in port A increases. This corresponds to the movement of the rod inside the cylinder.

Values	`Pressure at A causes positive displacement of R relative to C` \| `Pressure at A causes negative displacement of R relative to C`
Default value	`Pressure at A causes positive displacement of R relative to C`
Program usage name	`orientation`
Evaluatable	No

# Piston cross-sectional area in chamber A — the cross-sectional area of the piston rod of the chamber A
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac

Details

The cross-sectional area of the piston rod on the side of the chamber A.

Units	`m^2` \| `um^2` \| `mm^2` \| `cm^2` \| `km^2` \| `in^2` \| `ft^2` \| `yd^2` \| `mi^2` \| `ha` \| `ac`
Default value	`0.01 m^2`
Program usage name	`piston_area_a`
Evaluatable	Yes

# Piston cross-sectional area in chamber B — the cross-sectional area of the piston rod of the chamber B
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac

Details

The cross-sectional area of the piston rod on the side of the chamber B.

Units	`m^2` \| `um^2` \| `mm^2` \| `cm^2` \| `km^2` \| `in^2` \| `ft^2` \| `yd^2` \| `mi^2` \| `ha` \| `ac`
Default value	`0.01 m^2`
Program usage name	`piston_area_b`
Evaluatable	Yes

# Piston stroke — stroke of the piston
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The maximum possible displacement of the piston.

Units	`m` \| `um` \| `mm` \| `cm` \| `km` \| `in` \| `ft` \| `yd` \| `mi` \| `nmi`
Default value	`0.1 m`
Program usage name	`stroke`
Evaluatable	Yes

# Dead volume in chamber A — the volume of liquid in the chamber A, at which the movement of the piston is 0
m^3 | um^3 | mm^3 | cm^3 | km^3 | ml | l | gal | igal | in^3 | ft^3 | yd^3 | mi^3

Details

The volume of liquid in the chamber A at the value of the piston displacement 0. This volume of liquid corresponds to the position of the piston, at which it is located at the top in relation to the end cap of the actuator.

Units	`m^3` \| `um^3` \| `mm^3` \| `cm^3` \| `km^3` \| `ml` \| `l` \| `gal` \| `igal` \| `in^3` \| `ft^3` \| `yd^3` \| `mi^3`
Default value	`1e-05 m^3`
Program usage name	`dead_volume_a`
Evaluatable	Yes

# Dead volume in chamber B — the volume of liquid in the chamber B, at which the movement of the piston is 0
m^3 | um^3 | mm^3 | cm^3 | km^3 | ml | l | gal | igal | in^3 | ft^3 | yd^3 | mi^3

Details

The volume of liquid in the chamber B at the value of the piston displacement 0. This volume of liquid corresponds to the position of the piston, at which it is located at the top in relation to the end cap of the actuator.

Units	`m^3` \| `um^3` \| `mm^3` \| `cm^3` \| `km^3` \| `ml` \| `l` \| `gal` \| `igal` \| `in^3` \| `ft^3` \| `yd^3` \| `mi^3`
Default value	`1e-05 m^3`
Program usage name	`dead_volume_b`
Evaluatable	Yes

# Environment pressure specification — the method of setting the ambient pressure
Atmospheric pressure | Specified pressure

Details

The method of setting the ambient pressure. Option Atmospheric pressure sets the ambient pressure equal to 0.101325 MPa.

Values	`Atmospheric pressure` \| `Specified pressure`
Default value	`Atmospheric pressure`
Program usage name	`pressure_type`
Evaluatable	No

# Environment pressure — ambient pressure
Pa | uPa | hPa | kPa | MPa | GPa | kgf/m^2 | kgf/cm^2 | kgf/mm^2 | mbar | bar | kbar | atm | ksi | psi | mmHg | inHg

Details

User-defined ambient pressure.

Dependencies

To use this parameter, set for the parameter Environment pressure specification meaning Specified pressure.

Units	`Pa` \| `uPa` \| `hPa` \| `kPa` \| `MPa` \| `GPa` \| `kgf/m^2` \| `kgf/cm^2` \| `kgf/mm^2` \| `mbar` \| `bar` \| `kbar` \| `atm` \| `ksi` \| `psi` \| `mmHg` \| `inHg`
Default value	`0.101325 MPa`
Program usage name	`p_specified`
Evaluatable	Yes

Hard Stop

# Hard stop model — choosing a rigid 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

Selecting a model for the force acting on the piston when it is in extreme positions. For more information, see the block Translational 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	`hardstop_model`
Evaluatable	No

# Hard stop stiffness coefficient — stiffness coefficient
N/m | mN/m | kN/m | MN/m | GN/m | kgf/m | lbf/ft | lbf/in

Details

The coefficient of piston stiffness.

Units	`N/m` \| `mN/m` \| `kN/m` \| `MN/m` \| `GN/m` \| `kgf/m` \| `lbf/ft` \| `lbf/in`
Default value	`1e10 N/m`
Program usage name	`k_hard_stop`
Evaluatable	Yes

# Hard stop damping coefficient — damping coefficient
N*s/m | kgf*s/m | lbf*s/ft | lbf*s/in

Details

Piston damping coefficient.

Units	`Ns/m` \| `kgfs/m` \| `lbfs/ft` \| `lbfs/in`
Default value	`150.0 N*s/m`
Program usage name	`C_hard_stop`
Evaluatable	Yes

# Transition region — range of action of the rigid stop model
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The area of operation of the rigid stop. Outside of this range for the extreme positions of the piston Hard stop model it is not applied, and the additional force from the stop side does not act on the piston.

Dependencies

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

Units	`m` \| `um` \| `mm` \| `cm` \| `km` \| `in` \| `ft` \| `yd` \| `mi` \| `nmi`
Default value	`0.1 mm`
Program usage name	`transition_region`
Evaluatable	Yes

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

Details

The ratio of the final and initial relative velocity between the rod and the stop after the rod rebounds.

Dependencies

To use this parameter, set for the parameter Hard stop model meaning Based on coefficient of restitution.

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

# Static contact speed threshold — threshold value of the relative velocity between the rod and the stop before the collision
m/s | mm/s | cm/s | km/s | m/hr | km/hr | in/s | ft/s | mi/s | ft/min | mi/hr | kn

Details

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

Dependencies

To use this parameter, set for the parameter Hard stop model meaning Based on coefficient of restitution.

Units	`m/s` \| `mm/s` \| `cm/s` \| `km/s` \| `m/hr` \| `km/hr` \| `in/s` \| `ft/s` \| `mi/s` \| `ft/min` \| `mi/hr` \| `kn`
Default value	`0.001 m/s`
Program usage name	`v_static_contact_threshold`
Evaluatable	Yes

# Static contact release force threshold — the threshold value of the force required to transition from the contact state to the free state
N | nN | uN | mN | kN | MN | GN | dyn | lbf | kgf

Details

The minimum force required to remove the rod from the static contact state.

Dependencies

To use this parameter, set for the parameter Hard stop model meaning Based on coefficient of restitution.

Units	`N` \| `nN` \| `uN` \| `mN` \| `kN` \| `MN` \| `GN` \| `dyn` \| `lbf` \| `kgf`
Default value	`0.001 N`
Program usage name	`F_static_contact_release_threshold`
Evaluatable	Yes

Cushion A

# Cylinder A end cushioning — the option of modeling piston braking due to the action of a damper

Details

Whether the deceleration of the piston in its extreme positions is taken into account. For more information, see the see the block Cylinder Cushion (IL).

Default value	`false (switched off)`
Program usage name	`enable_cylinder_cushion_a`
Evaluatable	No

# Cushion plunger cross-sectional area — the cross-sectional area of the shock-absorbing plunger
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac

Details

The cross-sectional area of the shock-absorbing plunger.

Dependencies

To use this option, check the box Cylinder A end cushioning.

Units	`m^2` \| `um^2` \| `mm^2` \| `cm^2` \| `km^2` \| `in^2` \| `ft^2` \| `yd^2` \| `mi^2` \| `ha` \| `ac`
Default value	`0.0001 m^2`
Program usage name	`plunger_area_a`
Evaluatable	Yes

# Cushion plunger length — the length of the shock-absorbing plunger
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The length of the shock-absorbing plunger.

Dependencies

To use this option, check the box Cylinder A end cushioning.

Units	`m` \| `um` \| `mm` \| `cm` \| `km` \| `in` \| `ft` \| `yd` \| `mi` \| `nmi`
Default value	`0.001 m`
Program usage name	`plunger_length_a`
Evaluatable	Yes

# Cushion orifice area — the area of the opening between the damper chambers
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac

Details

The area of the opening between the damper chambers.

Dependencies

To use this option, check the box Cylinder A end cushioning.

Units	`m^2` \| `um^2` \| `mm^2` \| `cm^2` \| `km^2` \| `in^2` \| `ft^2` \| `yd^2` \| `mi^2` \| `ha` \| `ac`
Default value	`1e-06 m^2`
Program usage name	`cushioning_valve_area_a`
Evaluatable	Yes

# Leakage area between plunger and cushion sleeve — the area of the gap between the damper plunger and the bushing
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac

Details

The area of the gap between the damper plunger and the bushing. The parameter supports computational stability of the simulation, ensuring continuity of the flow.

Dependencies

To use this option, check the box Cylinder A end cushioning.

Units	`m^2` \| `um^2` \| `mm^2` \| `cm^2` \| `km^2` \| `in^2` \| `ft^2` \| `yd^2` \| `mi^2` \| `ha` \| `ac`
Default value	`1e-07 m^2`
Program usage name	`plunger_leakage_area_a`
Evaluatable	Yes

# Check valve cracking pressure differential — the pressure drop at which the check valve begins to open
Pa | uPa | hPa | kPa | MPa | GPa | kgf/m^2 | kgf/cm^2 | kgf/mm^2 | mbar | bar | kbar | atm | ksi | psi | mmHg | inHg

Details

The pressure at which the valve is triggered. When the pressure difference in port A and If the value of this parameter is equal to or exceeds, the non-return valve of the damper begins to open.

Dependencies

To use this option, check the box Cylinder A end cushioning.

Units	`Pa` \| `uPa` \| `hPa` \| `kPa` \| `MPa` \| `GPa` \| `kgf/m^2` \| `kgf/cm^2` \| `kgf/mm^2` \| `mbar` \| `bar` \| `kbar` \| `atm` \| `ksi` \| `psi` \| `mmHg` \| `inHg`
Default value	`0.01 MPa`
Program usage name	`delta_p_crack_a`
Evaluatable	Yes

# Check valve maximum pressure differential — pressure drop required to fully open the check valve
Pa | uPa | hPa | kPa | MPa | GPa | kgf/m^2 | kgf/cm^2 | kgf/mm^2 | mbar | bar | kbar | atm | ksi | psi | mmHg | inHg

Details

Maximum pressure drop of the damper check valve. This parameter sets the upper pressure limit so that the system pressure remains realistic.

Dependencies

To use this option, check the box Cylinder A end cushioning.

Units	`Pa` \| `uPa` \| `hPa` \| `kPa` \| `MPa` \| `GPa` \| `kgf/m^2` \| `kgf/cm^2` \| `kgf/mm^2` \| `mbar` \| `bar` \| `kbar` \| `atm` \| `ksi` \| `psi` \| `mmHg` \| `inHg`
Default value	`0.1 MPa`
Program usage name	`delta_p_max_a`
Evaluatable	Yes

# Check valve maximum area — the area of the fully open check valve
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac

Details

The cross-sectional area of the non-return valve opening in the fully open position.

Dependencies

To use this option, check the box Cylinder A end cushioning.

Units	`m^2` \| `um^2` \| `mm^2` \| `cm^2` \| `km^2` \| `in^2` \| `ft^2` \| `yd^2` \| `mi^2` \| `ha` \| `ac`
Default value	`0.0001 m^2`
Program usage name	`check_valve_max_area_a`
Evaluatable	Yes

# Check valve leakage area — leakage area with the non-return valve fully closed
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac

Details

The total area of possible leaks when the check valve is fully closed. Any area less than this value increases smoothly to the specified leakage area. This value contributes to computational robustness by maintaining continuity of flow.

Dependencies

To use this option, check the box Cylinder A end cushioning.

Units	`m^2` \| `um^2` \| `mm^2` \| `cm^2` \| `km^2` \| `in^2` \| `ft^2` \| `yd^2` \| `mi^2` \| `ha` \| `ac`
Default value	`1e-10 m^2`
Program usage name	`check_valve_leakage_area_a`
Evaluatable	Yes

# Smoothing factor — numerical smoothing factor

Details

The continuous smoothing coefficient, which ensures smooth opening by correcting for the valve characteristics in the almost open and almost closed positions. Set a non-zero value less than one to increase the stability of the simulation.

Dependencies

To use this option, check the box Cylinder A end cushioning.

Default value	`0.01`
Program usage name	`smoothing_factor_a`
Evaluatable	Yes

Cushion B

# Cylinder B end cushioning — option to simulate piston braking due to the action of a damper

Details

Whether the deceleration of the piston in its extreme positions is taken into account. For more information, see the see the block Cylinder Cushion (IL).

Default value	`false (switched off)`
Program usage name	`enable_cylinder_cushion_b`
Evaluatable	No

# Cushion plunger cross-sectional area — the cross-sectional area of the shock-absorbing plunger
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac

Details

The cross-sectional area of the shock-absorbing plunger.

Dependencies