Need help extracting Elemental stiffness and mass matrices

[HarshithHyphen]

Performing Modal Analysis on plate geometry with SOLID185 element.
The solver skips writing stiffness matrix in the emat file.

[mikerife]

Hi @HarshithHyphen you will need to provide more information...I just tried a simple model and the emat file was created as expected. If you can't share the input file try this one. I used Python 3.12, MAPDL 25.2, PyMAPDL 0.71.0

from ansys.mapdl.core import launch_mapdl
import os
path = os.getcwd()
exec_file = r"C:\Program Files\ANSYS Inc\v252\ansys\bin\winx64\ansys252.exe"

mapdl = launch_mapdl(run_location = path, exec_file = exec_file)
print(mapdl)

mapdl.clear()
mapdl.prep7()
mapdl.et(1, 185)
mapdl.mp('ex', 1, 1E7)
mapdl.mp('dens', 1, 0.0005)
mapdl.mp('nuxy', 1, 0.28)
mapdl.block(0, 10, 0, 2, 0, 1)
mapdl.esize(.5)
mapdl.vmesh(1)


mapdl.nsel('s', 'loc', 'x', 0)
mapdl.d('all', 'all', 0)
mapdl.allsel()
mapdl.finish()

mapdl.solution()
mapdl.antype('modal')
mapdl.modopt('lanb', 6)
mapdl.ematwrite('yes')
mapdl.solve()
mapdl.finish()

mapdl.exit()

[HarshithHyphen]

My bad. I dont know how to extract elemental mass and stiffness matrices. I dont see examples anywhere.

from ansys.mapdl import reader as pymapdl_reader
emat_file = pymapdl_reader.read_binary('file.emat')
dof_ref, element_data = emat_file.read_element(0)

print(element_data)

[mikerife]

@HarshithHyphen Ok, that is a label bug and not a data bug. The EMAT file does not store stresses...it does store 'stress stiffening' terms if availalbe (i.e. from a pre-stressed modal).