Slider-Crank
Crank and slide mechanism.
Description
The Slider-Crank unit represents the crank-slider mechanism as a converter between the continuous rotary motion of the crank and the reciprocating motion of the slider.
The mechanism has two connections:
-
Port C corresponds to the crank and represents the rotary mechanical port.
-
Port S corresponds to the slider and represents the translational mechanical port.
The parameters Crank radius and Rod length describe the geometry of the mechanism. The inertia of the crank, given by the Crank inertia parameter, is required to pass the top and bottom dead centre when the connecting rod is exactly at the centre of the crank.
Consideration of both mechanism stiffness and damping ratio, given by the Slider stiffness and Slider damping parameters, is necessary to reduce the inertial coupling between the ports; too stiff a coupling can cause computational problems. The block provides stiffness and damping between the ideal slider position (calculated from the geometry) and the actual position of the mechanical progressive port S. This matching avoids direct non-linear coupling between the ports. The higher stiffness results in a motion closer to ideal, but increases the computational stiffness of the system. Damping helps to smooth out the oscillations that can be caused by this stiffness of the system.
Ports
C - crank
`rotational mechanics
A mechanical rotary port, corresponding to a crank.
S - slider
translational mechanics
Mechanical progressive port, corresponds to a slider.
Parameters
Crank radius, m - crank radius
0.1 m (by default)
Crank radius. The parameter value must be greater than zero.
Rod length, m - connecting rod length
0.2 m (by default).
The length of the connecting rod connecting the crank and the ram. The parameter value must be greater than Crank radius.
Crank inertia, kg*m² - crank moment of inertia
0.01 kg*m² (by default).
The crank moment of inertia required to pass the top and bottom dead centre when the connecting rod is exactly at the centre of the crank. The value of the parameter must be greater than zero.
Slider stiffness, N/m - slider position stiffness
1e6 N/m (by default).
Together with Slider damping provides a pliability that helps to reduce inertial coupling between ports. Higher stiffness results in motion that is closer to ideal, but increases the stiffness of the system. The parameter value should be greater than zero.
Slider damping, N/(m/s) - slider damping coefficient
`1e3 N/(m/s) (by default)
Together with Slider stiffness, pliability is provided to help reduce inertial coupling between holes. Higher damping values smooth out oscillation that can be caused by stiffness. The parameter value should be greater than zero.
Initial value of crank angle, rad - initial value of crank angle
0.0 (By default).
Initial value of crank angle.
Initial value of crank velocity, rad/s - initial value of crank velocity
`0.0 (by default).
Initial value of crank velocity.