Loads¶
Loads are the forces and moments that are exerted on points and frames in the model, respectively.
Load Types
An external force acts on a single point, with vector components x, y, and z defined in the reference frame.
An actuated force acts with equal and opposite magnitude on two points, with vector components x, y, and z defined in the reference frame.
An external moment acts on a single frame, about a vector with components x, y, and z defined in the reference frame.
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.
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.
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.