Gravity and Base Excitation
Gravity is a global feature that applies forces to all features in the physics interface having a density, mass, or mass distribution. The gravitational force acts in a fixed spatial direction
e
g
. Consider a domain feature having a density of
ρ
, the gravitational force is
where
g
is the acceleration of gravity. The default value of
g
is the earth’s
standard acceleration of gravity
, having the value of
g_const
=
9.8066
m/s
2
.
Base excitation is similar to gravity, but has two distinct properties: The sign is reversed (the acceleration of the foundation is given) and it defines variables for the global, room fixed, accelerations.
