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Navigation: Library > Iconic Diagrams > Hydraulics > Cylinders > CylinderDouble |
  
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Iconic Diagrams\Hydraulics\Cylinders
Domains: Continuous. Size: 1-D. Kind: Iconic Diagrams (Hydraulics/Translational).
This model is the extended model of a double acting cylinder with mass, friction and end stops.
c
The volume of the chambers is given by:
Va = Vdead + Aa*(x + x_initial)
Vb = Vdead + Ab*(stroke - x - x_initial)
with Aa the piston area and Ab the effective area at the rod side. x is the piston position and Vdead the initial volume when piston position is zero. The piston areas Aa and Ab are related to the piston diameter dp and rod diameter dr by:
Aa = pi * dp^2 / 4
Ab = pi * dp^2 / 4 - pi * dr^2 / 4
The travel of the piston is restricted. At the cylinder heads two collision models prevent the piston from traveling any further. The friction between the piston and the cylinder walls is modeled by static and viscous friction.
When two cylinders are used in parallel, the chambers are connected and the resulting model will have algebraic loops. To prevent this, the special_use implementation can be used. In this implementation, the volumes of the cylinder are described with a Parasitic Volume.
Ports |
Description |
pa, pb p_barrel, p_rod |
hydraulic ports translation ports |
Causality |
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preferred pressure out pa preferred force out pm |
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Parameters |
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Vdead B stroke x_initial dp dr m_barrel m_rod kc dc Fc dv slope |
rest volume of oil in cylinder chamber when closed, [m3] effective bulk modulus [Pa] stroke length [m] starting position of piston [m] piston diameter [m] rod diameter [m] barrel mas [kg] rod and piston mass [kg] stiffness during collision with cylinder heads [N/m] damping during collision with cylinder heads [N.s/m] static friction [N] viscous friction coefficient [N.s/m] steepness of the static friction curve [] |
When a the cylinder piston collides with the cylinder heads, simulation may get very slow or even become unstable. In these cases you are advised to use the BDF-method with default settings. Try to change the absolute integration error until a stable simulation is obtained!