Loads

Loads are the forces and moments that are exerted on points and frames in the model, respectively.

External Force

An external force acts on a single point, with vector components x, y, and z defined in the reference frame.

Parameters

:param name: string

Name given to the force.

:param ref_frame_key: string

Reference frame in which the vector components of the force are defined.

:param ref_point_key: string

Point upon which the force acts.

:param force: numeric

Force magnitude.

:param x: numeric

X-component of the vector aligned with the force.

:param y: numeric

Y-component of the vector aligned with the force.

:param z: numeric

Z-component of the vector aligned with the force. 

Actuated Force

An actuated force acts with equal and opposite magnitude on two points, with vector components x, y, and z defined in the reference frame. 

Parameters

:param name: string

Name given to the force.

:param ref_frame_key: string

Reference frame in which the vector components of the force are defined.

:param start_point: string

First point upon which the force acts.

:param end_point: string

Second point upon which the force acts, with negative magnitude.

:param force: numeric

Force magnitude.

:param x: numeric

X-component of the vector aligned with the force.

:param y: numeric

Y-component of the vector aligned with the force.

:param z: numeric

Z-component of the vector aligned with the force.

External Moment

An external moment acts on a single frame, about a vector with components x, y, and z defined in the reference frame.

Parameters

:param name: string

Name given to the moment.

:param ref_frame_key: string

Reference frame in which the vector components of the moment are defined.

:param loaded_frame_key: string

Frame upon which the moment acts.

:param moment: numeric

Moment magnitude.

:param x: numeric

X-component of the vector about which the moment is defined.

:param y: numeric

Y-component of the vector about which the moment is defined.

:param z: numeric

Z-component of the vector about which the moment is defined.

Actuated Moment

An actuated moment acts with equal and opposite magnitude on two frames, about a vector with components x, y, and z defined in the reference frame.

Parameters

:param name: string

Name given to the moment.

:param ref_frame_key: string

Reference frame in which the vector components of the moment are defined.

:param first_frame_key: string

First frame upon which the moment acts.

:param second_frame_key: string

Second frame upon which the moment acts, with negative magnitude.

:param moment: numeric

Moment magnitude.

:param x: numeric

X-component of the vector about which the moment is defined.

:param y: numeric

Y-component of the vector about which the moment is defined.

:param z: numeric

Z-component of the vector about which the moment is defined.

Translational Spring-Damper

A translational spring/damper induces an attractive force between two points that is colinear with a vector drawn from the start to end point. The force magnitude is

    F = k (x - e) + c x'

where k is the spring stiffness, x is the distance between the two points, e is an equilibrium length of the spring, c is the damping constant, and x' is the differential speed between the two points.

Parameters

:param start_point: string

Key for the first point.

:param end_point: string

Key for the second point.

:param k: string or numeric

Parameter corresponding to the spring stiffness constant.

:param c: string or numeric

Parameter corresponding to the damping constant.

:param equilibrium: string or numeric

Parameter corresponding to the equilibrium length of the spring.

Rotational Spring-Damper

A rotational spring/damper induces an attractive moment between two frames about the rotation axis corresponding to the relative orientation of the frames. The moment magnitude is

    M = k θ + c θ'

where k is the spring stiffness, θ is the angle between the two frames, c is the damping constant, and θ' is the differential angular speed between the two frames.

Parameters

:param ref_point_key: string

Key for the point where the rotational spring is visualized.

:param first_frame_key: string

Key for the first frame.

:param second_frame_key: string

Key for the second frame.

:param k: string or numeric

Parameter corresponding to the spring stiffness constant.

:param c: string or numeric

Parameter corresponding to the damping constant.