Nonlinear Rotational Damper
Nonlinear damper in mechanical rotational systems.
blockType: Engee1DMechanical.Elements.Rotational.NonlinearDamper
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Description
Block Nonlinear Rotational Damper It is a nonlinear rotational damper. The polynomial and tabular parameterizations determine the nonlinear relationship between the torque and the relative angular velocity. The torque can be symmetrical or asymmetrical relative to the zero velocity point. The unit applies equal opposite torques to two non-directional ports.
The symmetric polynomial parameterization determines the torque for positive and negative relative angular velocities according to the expression:
where
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— the torque transmitted through the damper;
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— damping coefficients;
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— relative angular velocity between ports R and C:
where
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— absolute angular velocity of the port R;
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— the absolute angular velocity of the port C.
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To avoid zero crossings that slow down the simulation, eliminate the sign function from the polynomial expression by specifying an odd polynomial ( ).
The two-way polynomial parameterization determines the torque for positive and negative relative velocities according to the expression:
where
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— damping coefficients for positive relative speeds;
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— damping coefficients for negative relative speeds.
Both polynomial parameterizations use a fifth-order polynomial. To use a lower-order polynomial, set the higher-order coefficients to zero. For polynomials of order greater than five, perform an approximation with a polynomial of order no higher than the fifth, or use parameterization based on tabular data.
Parameterization according to the search table determines the damping torque based on the specified angular velocity and torque vectors. If a point with zero angular velocity and zero moment is not included in the specified vectors, the block automatically adds it as a data point at the origin.
Parameters
Parameters
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Parameterization —
parameterization of damping
By polynomial | By table lookup
Details
Choose the type of torque parameterization: a polynomial or a search table.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
No |
# Symmetry — symmetry of damping
Details
Select this option to use symmetric parameterization. If the box is not checked, the block uses two-way parameterization.
Dependencies
To use this parameter, set for the parameter Parameterization meaning By polynomial.
| Default value |
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| Program usage name |
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| Evaluatable |
No |
#
Vector of damping coefficients —
damping coefficients for parameterization by a polynomial
N*m/(rad/s) | ft*lbf/(rad/s)
Details
Damping coefficients for symmetric parametrization by a polynomial.
Dependencies
To use this parameter, set for the parameter Parameterization meaning By polynomial and check the box Symmetry.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |