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External Force and Torque

General force and torque arising outside the modeled system

Library

Forces and Torques

Description

This block represents a general force and torque that an external agency applies on a rigid body frame. The force and torque input can be constant or it can vary with time. The block provides a set of physical signal ports that you use to specify this input. The ports are hidden by default. Selecting an actuation mode exposes the corresponding physical signal port.

Each force and torque input acts on the origin of the follower frame in a direction that depends on the chosen force type and resolution frame. A force/torque vector component acts along/about the associated Cartesian axis, resolved in the chosen resolution frame. For example, the Force(X) input acts along the X axis of the resolution frame. A complete force/torque vector acts in the general direction that its components specify, resolved in the chosen resolution frame.

A force input with a positive value acts along the positive direction of the associated axis. A torque input with a positive value acts about the associated axis according to the right-hand rule.

Dialog Box and Parameters

The dialog box contains a Properties area with expandable Force and Torque Sections. Expanding these sections exposes the force and torque types that you can select.

Actuation: Force

Select the force inputs to specify and the frame to resolve them in.

Force Resolution Frame

Select the frame to resolve each force signal in. The components of the force vector align with the axes of the resolution frame. The default setting is Attached Frame. The table summarizes the resolution frames that you can select.

Resolution FrameDescription
WorldResolve each force component in the World frame of the model.
Attached FrameResolve each force component in the follower frame of the External Force and Torque block. The follower frame is the attached frame of the block.

Force Inputs

Select the force inputs to specify. Options include the complete force vector and the separate components of that vector. Selecting a force input exposes the physical signal port associated with that input. Use that port to specify the force input via physical signals. The table summarizes the force inputs that you can select.

Force InputDescriptionInput
Force(X), Force(Y), Force(Z)Specify separately the force components acting on the origin of the follower frame along the X, Y, and Z axes of the resolution frameScalar
ForceSpecify the complete force vector [fx fy fz] acting on the origin of the follower frame along the X, Y, and Z axes of the resolution frameThree-element vector

Actuation: Torque

Select the torque inputs to specify and the frame to resolve them in.

Torque Resolution Frame

Select the frame to resolve each torque signal in. The components of the torque vector align with the axes of the resolution frame. The default setting is Attached Frame. The table summarizes the resolution frames that you can select.

Resolution FrameDescription
WorldResolve each torque component in the World frame of the model.
Attached FrameResolve each torque component in the follower frame of the External Force and Torque block. The follower frame is the attached frame of the block.

Torque Inputs

Select the torque inputs to specify. Options include the complete torque vector and the separate components of that vector. Selecting a torque input exposes the physical signal port associated with that input. Use that port to specify the torque input via physical signals. The table summarizes the torque inputs that you can select.

Force InputDescriptionInput
Torque(X), Torque(Y), Torque(Z)Specify separately the torque components acting on the origin of the follower frame about the X, Y, and Z axes of the resolution frameScalar
TorqueSpecify the complete torque vector [fx fy fz] acting on the origin of the follower frame about a general direction in the resolution frameThree-element vector

Ports

The block contains frame port F, representing the follower frame. Selecting an actuation mode exposes additional physical signal ports. Use the ports to input the selected actuation signals.

Each physical signal port has a unique label. The table identifies the actuation modes that the port labels correspond to.

Port LabelDescription
fx, fy, fzForce vector components acting on the origin of the follower frame along the X, Y, and Z axes, respectively
fForce vector [fx, fy, fz] acting on the origin of the follower frame along a general direction [X Y Z]
tx, ty, tzTorque vector components acting on the origin of the follower frame about the X, Y, and Z axes, respectively
tTorque vector [tx ty tz] acting on the origin of the follower frame about a general direction [X Y Z]

See Also

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