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198 RIGID BODIES
DYNAMICS
DYNAMICS
RIGID BODIES 199
Start At
This denes the length at which plastic deformation will begin, specied as a
percentage of the Rest Length (Elastic tab). For example, if you enter a value of
200% and Rest Length = 10 m, plastic deformation will start when the spring is
20 m long.
Stiffness X
Use Stiffness X to set the stiffness of the spring for plastic deformation. The value
must be dened as a percentage of Stiffness (Elastic tab). For example, if you enter
a Stiffness X value of 10% and Stiffness = 5, the stiffness of the spring during its
elastic state will be 0.5.
Damping X
Damping X controls the strength of damping for the plastic state, dened as a
percentage of Damp (Elastic tab). For example, with Damping X set to 50% and Damp
set to 0.1, the damping during the plastic state will be 0.05.
Drag
This setting will ensure that the attached objects are damped while the spring is
undergoing plastic deformation. This can be thought of as a drag eld that affects
the two attached objects only.
Break Tab
The options on the Break tab
dene at what point a rigid
body spring will lose all of its
properties — literally break.
Like a real spring, Dynamics springs can be made to snap if you stretch them too
far. Before a real spring snaps, it will rst undergo elastic deformation followed by
plastic deformation.