Connector Damping Behavior

In the simplest case of linear uncoupled damping you define the damping coefficients for the selected components (that is, $C_{11}$ for component 1, $C_{22}$ for component 2, etc.), which are used in the equation

where $F_i$ is the force or moment in the $i^{\mathrm{th}}$ component of relative motion and $v_i$ is the velocity or angular velocity in the $i^{\mathrm{th}}$ direction. The damping coefficient can depend on frequency (in Abaqus/Standard), temperature, and field variables. See Input Syntax Rules for further information about defining data as functions of frequency, temperature, and field variables.

In most cases if frequency-dependent damping behavior is specified in an Abaqus/Standard analysis procedure, the data at zero frequency is used. The exceptions are direct-solution steady-state dynamics, subspace-based steady-state dynamics, and natural or complex eigenvalue extraction.

CONNECTOR BEHAVIOR, NAME=name
CONNECTOR DAMPING, COMPONENT=component number, 
DEPENDENCIES=n

Interaction module: connector section editor: AddDamping: Definition: Linear, Force/Moment: component or components, Coupling: Uncoupled

In the linear coupled case you define the damping coefficient matrix components, $C_{ij}$, which are used in the equation

where $F_i$ is the force in the $i^{\mathrm{th}}$ component of relative motion, $v_j$ is the velocity in the $j^{\mathrm{th}}$ component, and $C_{ij}$ is the coupling between the $i^{\mathrm{th}}$ and $j^{\mathrm{th}}$ components. The C matrix is assumed to be symmetric, so only the upper triangle of the matrix is specified. In connectors with kinematic constraints the entries that correspond to the constrained components of relative motion will be ignored. The damping coefficient can depend on temperature and field variables. See Input Syntax Rules for further information about defining data as functions of temperature and field variables.

CONNECTOR BEHAVIOR, NAME=name
CONNECTOR DAMPING, DEPENDENCIES=n

Interaction module: connector section editor: AddDamping: Definition: Linear, Force/Moment: component or components, Coupling: Coupled

As with linear coupled elastic behavior (Connector Elastic Behavior), Abaqus/Standard allows you to define an unsymmetric coupled viscous damping matrix. In the linear coupled case you define the damping coefficient matrix components, $C_{ij}$, which are used in the equation

where $F_i$ is the force in the $i^{\mathrm{th}}$ component of relative motion, $v_j$ is the velocity in the $j^{\mathrm{th}}$ component, and $C_{ij}$ is the coupling between the $i^{\mathrm{th}}$ and $j^{\mathrm{th}}$ components. The C matrix is assumed to be unsymmetric, so the entire matrix is specified. The entries that correspond to the constrained components of relative motion are ignored. When the unsymmetric matrix storage and solution scheme are used, the damping coefficients can depend on frequency, temperature, and field variables. See Input Syntax Rules for further information about defining data as functions of frequency, temperature and field variables.

CONNECTOR BEHAVIOR, NAME=name
CONNECTOR DAMPING, UNSYMM, 
FREQUENCY DEPENDENCE=ON

For nonlinear damping you specify forces or moments as nonlinear functions of the velocity in the available components of relative motion directions, $F_i\left(v_1,v_2,\mathrm{\dots }\right)$. These functions can also depend on temperature and field variables. See Input Syntax Rules for further information about defining data as functions of temperature and field variables.

Refer to the example in Figure 1.

Figure 1. Simplified connector model of a shock absorber.

In addition to the torsional spring resisting relative rotations, the shock absorber damps translational motion along the line of the shock with a dashpot. To include a nonlinear dashpot behavior that is dependent on the relative position between the attachment points, use the following input:

CONNECTOR BEHAVIOR, NAME=sbehavior
...
CONNECTOR DAMPING, COMPONENT=1,
 INDEPENDENT COMPONENTS=POSITION, NONLINEAR
1
1500.0, 0.1, 0.0
1625.0, 0.2, 0.0
1750.0, 0.1, 10.0
1925.0, 0.2, 10.0

Structural connector damping is supported in steady-state dynamics and modal transient procedures that support non-diagonal damping (for example, direct solution steady-state dynamics).

In both the direct-solution and subspace-based steady-state dynamic procedures, the viscous or structural damping defined using an uncoupled connector damping behavior may be frequency dependent. In other linear perturbation procedures connector damping behavior is ignored.