Engee documentation

Variable Translational Spring

Tension–compression spring with variable stiffness.

blockType: Engee1DMechanical.Elements.Translational.VariableSpring

variable translational spring

Path in the library:

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

Description

Block Variable Translational Spring It is a tension–compression spring with variable stiffness. The value of the variable spring stiffness coefficient is sent to the input port K. The value of the spring elasticity force is equal to the product of the value on the port K and the value of the relative linear displacement between two non-directional ports. The minimum value of the spring stiffness prevents non-physical values from occurring.

The value of the spring elasticity force satisfies the following expression:

where

  • — the force transmitted through the spring between two non-directional ports;

  • — the coefficient of spring stiffness;

  • — the minimum allowable spring stiffness coefficient;

  • is the relative offset between two non—directional ports, defined as ;

  • — initial spring deformation;

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

  • — the absolute offset of the non-directional port C.

The block applies equal opposing spring elastic forces to two non-directional ports. The sign of the spring force acting on port R is equal to the sign of the relative linear displacement between the two ports. The positive translational velocity corresponds to a positive force acting on port R and a negative force 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 — slave port
translational mechanics

Details

A non-directional progressive mechanical port connected to the positive end of a spring. The positive direction is from port R to port C.

Program usage name

rod_flange

# C — base port
translational mechanics

Details

A non-directional progressive mechanical port connected to the negative end of a spring. The positive direction is from port R to port C.

Program usage name

case_flange

Input

# K — variable spring stiffness
scalar

Details

Variable coefficient of spring stiffness.

Data types

Float64.
Complex numbers support

No

Parameters

Parameters

# Minimum spring rate — minimum spring stiffness factor
N/m | lbf/ft | lbf/in

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

N/m | lbf/ft | lbf/in
Default value

1.0 N/m
Program usage name

k_min
Evaluatable

Yes