Modelica.Mechanics.MultiBody.Examples.Loops.Utilities

Information

Package Content

Name	Description
Cylinder	Cylinder with rod and crank of a combustion engine
GasForce	Simple gas force computation for combustion engine
GasForce2	Rough approximation of gas force in a cylinder
CylinderBase	One cylinder with analytic handling of kinematic loop
Cylinder_analytic_CAD	One cylinder with analytic handling of kinematic loop and CAD visualization
EngineV6_analytic	V6 engine with analytic loop handling
Engine1bBase	Model of one cylinder engine with gas force

Modelica.Mechanics.MultiBody.Examples.Loops.Utilities.Cylinder

Parameters

Name	Description
animation	= true, if animation shall be enabled
cylinderTopPosition	Length from crank shaft to end of cylinder. [m]
pistonLength	Length of cylinder [m]
rodLength	Length of rod [m]
crankLength	Length of crank shaft in x direction [m]
crankPinOffset	Offset of crank pin from center axis [m]
crankPinLength	Offset of crank pin from center axis [m]
cylinderInclination	Inclination of cylinder [rad]
crankAngleOffset	Offset for crank angle [rad]
cylinderLength	Maximum length of cylinder volume [m]

Connectors

Name	Description
cylinder_a
cylinder_b
crank_a
crank_b

Modelica.Mechanics.MultiBody.Examples.Loops.Utilities.GasForce

Information

Parameters

Name	Description
L	Length of cylinder [m]
d	Diameter of cylinder [m]
k0	Volume V = k0 + k1*(1-x), with x = 1 + s_rel/L [m3]
k1	Volume V = k0 + k1*(1-x), with x = 1 + s_rel/L [m3]
k	Gas constant (p*V = k*T) [J/K]
Initialization
s_rel	Relative distance (= flange_b.s - flange_a.s) [m]

Connectors

Name	Description
flange_a	Left flange of compliant 1-dim. translational component
flange_b	Right flange of compliant 1-dim. translational component

Modelica.Mechanics.MultiBody.Examples.Loops.Utilities.GasForce2

Information

The gas force in a cylinder is computed as function of the relative distance of the two flanges. It is required that s_rel = flange_b.s - flange_a.s is in the range

    0 ≤ s_rel ≤ L

where the parameter L is the length of the cylinder. If this assumption is not fulfilled, an error occurs.

Parameters

Name	Description
L	Length of cylinder [m]
d	diameter of cylinder [m]
k0	Volume V = k0 + k1*(1-x), with x = 1 - s_rel/L [m3]
k1	Volume V = k0 + k1*(1-x), with x = 1 - s_rel/L [m3]
k	Gas constant (p*V = k*T) [J/K]
Initialization
s_rel	Relative distance (= flange_b.s - flange_a.s) [m]

Connectors

Name	Description
flange_a	Left flange of compliant 1-dim. translational component
flange_b	Right flange of compliant 1-dim. translational component

Modelica.Mechanics.MultiBody.Examples.Loops.Utilities.CylinderBase

Parameters

Name	Description
animation	= true, if animation shall be enabled
cylinderTopPosition	Length from crank shaft to end of cylinder. [m]
crankLength	Length of crank shaft in x direction [m]
crankPinOffset	Offset of crank pin from center axis [m]
crankPinLength	Offset of crank pin from center axis [m]
cylinderInclination	Inclination of cylinder [deg]
crankAngleOffset	Offset for crank angle [deg]
Piston
pistonLength	Length of cylinder [m]
pistonCenterOfMass	Distance from frame_a to center of mass of piston [m]
pistonMass	Mass of piston [kg]
pistonInertia_11	Inertia 11 of piston with respect to center of mass frame, parallel to frame_a [kg.m2]
pistonInertia_22	Inertia 22 of piston with respect to center of mass frame, parallel to frame_a [kg.m2]
pistonInertia_33	Inertia 33 of piston with respect to center of mass frame, parallel to frame_a [kg.m2]
Rod
rodLength	Length of rod [m]
rodCenterOfMass	Distance from frame_a to center of mass of piston [m]
rodMass	Mass of rod [kg]
rodInertia_11	Inertia 11 of rod with respect to center of mass frame, parallel to frame_a [kg.m2]
rodInertia_22	Inertia 22 of rod with respect to center of mass frame, parallel to frame_a [kg.m2]
rodInertia_33	Inertia 33 of rod with respect to center of mass frame, parallel to frame_a [kg.m2]

Connectors

Name	Description
cylinder_a
cylinder_b
crank_a
crank_b

Modelica.Mechanics.MultiBody.Examples.Loops.Utilities.Cylinder_analytic_CAD

Information

Parameters

Name	Description
animation	= true, if animation shall be enabled
cylinderTopPosition	Length from crank shaft to end of cylinder. [m]
crankLength	Length of crank shaft in x direction [m]
crankPinOffset	Offset of crank pin from center axis [m]
crankPinLength	Offset of crank pin from center axis [m]
cylinderInclination	Inclination of cylinder [deg]
crankAngleOffset	Offset for crank angle [deg]
Piston
pistonLength	Length of cylinder [m]
pistonCenterOfMass	Distance from frame_a to center of mass of piston [m]
pistonMass	Mass of piston [kg]
pistonInertia_11	Inertia 11 of piston with respect to center of mass frame, parallel to frame_a [kg.m2]
pistonInertia_22	Inertia 22 of piston with respect to center of mass frame, parallel to frame_a [kg.m2]
pistonInertia_33	Inertia 33 of piston with respect to center of mass frame, parallel to frame_a [kg.m2]
Rod
rodLength	Length of rod [m]
rodCenterOfMass	Distance from frame_a to center of mass of piston [m]
rodMass	Mass of rod [kg]
rodInertia_11	Inertia 11 of rod with respect to center of mass frame, parallel to frame_a [kg.m2]
rodInertia_22	Inertia 22 of rod with respect to center of mass frame, parallel to frame_a [kg.m2]
rodInertia_33	Inertia 33 of rod with respect to center of mass frame, parallel to frame_a [kg.m2]

Connectors

Name	Description
cylinder_a
cylinder_b
crank_a
crank_b

Modelica.Mechanics.MultiBody.Examples.Loops.Utilities.EngineV6_analytic

Parameters

Name	Description
animation	= true, if animation shall be enabled
replaceable model Cylinder	Cylinder type

Connectors

Name	Description
replaceable model Cylinder	Cylinder type
flange_b
frame_a

Modelica.Mechanics.MultiBody.Examples.Loops.Utilities.Engine1bBase

Information

This is a model of the mechanical part of one cylinder of an engine. The combustion is not modelled. The "inertia" component at the lower left part is the output inertia of the engine driving the gearbox. The angular velocity of the output inertia has a start value of 10 rad/s in order to demonstrate the movement of the engine.

The engine is modeled solely by revolute and prismatic joints. Since this results in a planar loop there is the well known difficulty that the cut-forces perpendicular to the loop cannot be uniquely computed, as well as the cut-torques within the plane. This ambiguity is resolved by using the option planarCutJoint in the Advanced menu of one revolute joint in every planar loop (here: joint B1). This option sets the cut-force in direction of the axis of rotation, as well as the cut-torques perpendicular to the axis of rotation at this joint to zero and makes the problem mathematically well-formed.

An animation of this example is shown in the figure below.