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# threedspringdamper

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# threedspringdamper

## Library

Iconic Diagrams\Mechanical\Translation\3DSmallAngles

## Use

Domains: Continuous. Size: 1-D/6-D. Kind: Iconic Diagrams (Translation,Rotation).

## Description

This model is the equivalent of the 1 degree of freedom model SpringDamper.emx. It model represents an ideal spring-damper. The model has a preferred force out causality. The corresponding constitutive equations then contain integrations. The element can also have the non-preferred velocity out causality. The constitutive equations then contain derivatives. The spring-damper model has separate high and low ports. The equations are

P.F = P_high.F = P_low.F

P.v = P_high.v - P_low.v

Force out causality (preferred):

X = int(P.v);

P.F = S*X + D*P.v;

Velocity out causality:

P.v = ddt(X);

X = S-1*(P.F - D*P.v);

## Interface

Ports

Description

P_high[6], P_low[6]

Both terminals of a port with 6 degrees of freedom.

Causality

preferred force out P

Variables

X

Vector with 6 spring extension values [m].

Parameters

S[6]

D[6]

Stiffness vector [N/m]

Damping vector [N.s/m]

## Initial Values

X_initial[6]

Vector with 6 initial extension values of the spring [m].

## Note

It is not possible in 20-sim to use vector elements with mixed units. Therefore element number 4 to 6 will be displayed with units [m/s] and [N] although it really is [rad/s] and [Nm] etc.!