MASS and STIFFNESS matrices in ABAQUS
MASS and STIFFNESS matrices in ABAQUS
(OP)
Hi, everybody
is there anybody who knows how to get the MASS and STIFFNESS matrices from the ABAQUS and, maybe let them write down to a file?
Thanks in advance,
ridbay
is there anybody who knows how to get the MASS and STIFFNESS matrices from the ABAQUS and, maybe let them write down to a file?
Thanks in advance,
ridbay





RE: MASS and STIFFNESS matrices in ABAQUS
Cheers,
-- drej --
RE: MASS and STIFFNESS matrices in ABAQUS
but i have already rewieved the *ELEMENT MATRIX OUTPUT and implemented the keywords therein... unfortunately i could not get the matrices up to now...
Should i write the keywords on "EDIT KEYWORDS" (which can be reached by clicking: Model -> Edit Keywords -> Model_Name)under the History output line?
and under which Procedure can i use it? General procedures such as Static, linear perturbation such as Frequency ?
or can you provide anymore explanation?
thanks
RE: MASS and STIFFNESS matrices in ABAQUS
In the static case:
kx = f (f = nodal forces, k = stiffness matrix, x = nodal displacements hence no mass matrix needed).
Eigenvalue (modal or free vibration):
kx + ma = 0 (m = mass matrix, a = nodal acceleration)
Dynamic (transient):
kx + ma + cv = f(t) (c = damping constant (Ns/m), v = nodal velocity, m = mass matrix)
I don't know the preprocessor you're using, but why not write out the deck manually and add the *ELEMENT MATRIX OUTPUT manually into the applicable part of the deck. Check in the manual for the correct position of this keyword in the deck, but I believe it should be located within the *STEP module. The matrices will then appear in your chosen file (or .dat if none) file.
E.g.
*STEP
etc
etc.
*ELEMENT MATRIX OUTPUT, OUTPUT FILE=FILENAME.EXT, MASS=YES, STIFFNESS=YES, ELSET=ELSET_NAME
*END STEP
Cheers,
-- drej --