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# CylinderSingleSpringReturn

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# CylinderSingleSpringReturn

## Library

Iconic Diagrams\Hydraulics\Cylinders

## Use

Domains: Continuous. Size: 1-D. Kind: Iconic Diagrams (Hydraulics/Translational).

## Description

This is the extended model of a single acting cylinder with mass, friction, end stops and a return spring to drive the cylinder back when there is no pressure in the chamber.

The volume of the chamber is given by:

V = Vdead + Aa*(x + x_initial)

with Aa the piston area, x the piston position and Vdead the initial volume when piston position is zero. The piston area Aa is related to the piston diameter dp by:

Aa = pi * dp^2 / 4

The driving force of the return spring is determined by two parameters: the force for piston position zero (Fspr_min) and the force when the piston is at the other side (Fspr_max). The spring constant (kspr) and initial spring position (x0) are calculated out of these parameters by:

kspr = (Fspr_max - Fspr_min)/stroke

x0 = -Fspr_min/kspr

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.

## Interface

 Ports Description pa p_barrel, p_rod hydraulic port translation ports Causality preferred pressure out pa preferred force out pm Parameters Vdead stroke x_initial dp m_barrel m_rod kc dc Fc dv slope Fspr_min Fspr_max rest volume of oil in cylinder chamber when closed [m3] stroke length [m] starting position of piston [m] piston diameter [m] barrel mass [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 [] minimum return spring force (at x = 0) maximum return spring force (at x = stroke)

## Note

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!