Nonlinear Rotational Spring
Torsional spring based on polynomial or table lookup parameterizations
Library
Simscape / Driveline / Couplings & Drives / Springs & Dampers
Description
The block represents a torsional spring with nonlinear torque-displacement curve. The spring torque magnitude is a general function of displacement. It need not satisfy Hooke’s law. Polynomial and table lookup parameterizations provide two ways to specify the torque-displacement relationship. The spring torque can be symmetric or asymmetric with respect to zero deformation.
对称多项式parameterization defines spring torque according to the expression:
where:
T— Spring force
k1,k2, ...,k5— Spring coefficients
θ— Relative displacement between ports R and C,
θinit— Initial spring deformation
θR— Absolute angular position of port R
θC— Absolute angular position of port C
At simulation start (t=0),θRandθCare zero, makingθequal toθinit.
To avoid zero-crossings that slow simulation, eliminate the sign function from the polynomial expression by specifying an odd polynomial (b2,b4= 0).
The two-sided polynomial parameterization defines spring torque according to the expression:
where:
k1t,k2t, ...,k5t— Spring tension coefficients
k1c,k2c, ...,k5c— Spring compression coefficients
Both polynomial parameterizations use a fifth-order polynomial expression. To use a lower-order polynomial, set the unneeded higher-order coefficients to zero. To use a higher-order polynomial, fit to a lower-order polynomial or use the table lookup parameterization.
The table lookup parameterization defines spring torque based on a set of torque and angular velocity vectors. If not specified, the block automatically adds a data point at the origin (zero angular velocity and zero torque).
Variables
Use theVariablestab to set the priority and initial target values for the block variables before simulating. For more information, seeSet Priority and Initial Target for Block Variables.
Ports
-
C
-
Rotational conserving port
-
R
-
Rotational conserving port
Parameters
- Parameterization
-
Select spring parameterization. Options are
By polynomial
andBy table lookup
.