Matrix or Vector | Shape Functions | Integration Points |
---|---|---|
Mass Matrix | None | None |
The element mass matrix is:
(13–17) |
where:
ρ = density (input as DENS on MP command) |
where a', b', c', d', e', and f' are user input (input on the R command) in the locations shown in the following table:
KEYOPT(3) = 0 | KEYOPT(3) = 2 | KEYOPT(3) = 3 | KEYOPT(3) = 4 | |
---|---|---|---|---|
a' | 1 | 1 | 1 | 1 |
b' | 2 | 1 | 1 | 1 |
c' | 3 | 1 | - | - |
d' | 4 | - | - | - |
e' | 5 | - | - | - |
f' | 6 | - | 2 | - |
For the mass summary, only the first real constant is used, regardless of which option of KEYOPT(3) is used. The precise mass summary used for three-dimensional models as well as analyses with inertial relief use the complete matrix.