Engee documentation

Variable Rotational Spring

Rotary spring with variable stiffness.

blockType: Engee1DMechanical.Elements.Rotational.VariableSpring

variable rotational spring

Path in the library:

/Physical Modeling/1D Mechanical/Couplings & Drives/Springs & Dampers/Variable Rotational Spring

Description

Block Variable Rotational Spring It is a rotary spring with a variable stiffness coefficient. The value of the variable spring stiffness coefficient is sent to the input port K. The value of the spring torque is equal to the product of the value on the port K and the value of the relative angular displacement between the two non-directional ports of rotation. The minimum value of the spring stiffness prevents non-physical values from appearing.

The torque of the spring satisfies the following expression:

where

  • — the torque transmitted through the spring;

  • — the coefficient of spring stiffness;

  • — the minimum allowable spring stiffness coefficient;

  • is the relative angular displacement measured between two non—directional rotation ports as follows: ;

  • — initial angular deformation between two non-directional rotation ports;

  • — absolute angular displacement of the non-directional rotation port R;

  • — the absolute angular displacement of the non-directional rotation port C.

The unit applies equal opposite torques of the springs to the two ports of rotation. The sign of the torque of the spring acting on the port R is equal to the sign of the relative angular velocity. The positive relative angular velocity corresponds to a positive damping moment acting on port R and a negative damping moment of the same magnitude acting on port C.

Assumptions and limitations

The value of the spring stiffness coefficient must be greater than zero.

Ports

Conserving

# R — rotation port
`rotational mechanics

Details

Non-directional port of rotation.

Program usage name

rod_flange

# C — rotation port
`rotational mechanics

Details

Non-directional port of rotation.

Program usage name

case_flange

Input

# K — spring stiffness
scalar

Details

The coefficient of stiffness of a spring.

Data types

Float64.
Complex numbers support

No

Parameters

Parameters

# Minimum spring rate — minimum spring stiffness factor
HP_DIN/rpm | N*m/rad | W*s/rad | m*mN/rad | HP_DIN*s/rad | ft*lbf/rad

Details

The minimum permissible spring stiffness coefficient. If the stiffness value at port K is less than this value, it is equated to it. The value of this parameter must be greater than zero.

Units

HP_DIN/rpm | N*m/rad | W*s/rad | m*mN/rad | HP_DIN*s/rad | ft*lbf/rad
Default value

0.01 N*m/rad
Program usage name

k_min
Evaluatable

Yes