Working with a ANSYS Element Matrix File (.emat)

The ANSYS element matrix file is a FORTRAN formatted binary file containing the following for each element:

  • Stiffness matrix

  • Mass matrix

  • Damping matrix

  • Stress stiffening matrix

  • Complex stiffness matrix

  • Element force vectors

Example

Load the element matrix file:

from ansys.mapdl import reader as pymapdl_reader
emat_file = pymapdl_reader.read_binary('file.emat')

Read a single element from the result file:

dof_ref, element_data = emat_file.read_element(0)

The dictionary element_data contains the entries used to construct stiffness, mass, and damping matrices. If recorded, the dictionary will also applied force vectors.

Applied Force

Read accumulated applied force for all nodes:

applied_force = emat_file.global_applied_force()

See emat_file.nnum for the sorted nodes this applied force corresponds to.

DOF Reference

Each degree of freedom index from read_element corresponds to a physical degree of freedom. The table of this correspondence is below:

Index

DOF

1

UX

2

UY

3

UZ

4

ROTX

5

ROTY

6

ROTZ

7

AX

8

AY

9

AZ

10

VX

11

VY

12

VZ

16

WARP

17

CONC

18

HDSP

19

PRES

20

TEMP

21

VOLT

22

MAG

23

ENKE

24

ENDS

25

EMF

26

CURR

27 - 32

Spares

EmatFile Object Methods

class ansys.mapdl.reader.emat.EmatFile(filename)

Enables pythonic access to an ANSYS element matrix file.

Parameters

filename (str) – File to open. Generally ends in *.emat.

Examples

>>> from ansys.mapdl import reader as pymapdl_reader
>>> emat_file = pymapdl_reader.read_binary('file.emat')
property eeqv

Element equivalence table. This table equates the number used for storage to the actual element number.

Notes

The ANSYS program stores all element data in the numerical order that the SOLUTION processor solves the elements. This table equates the order number used to the actual element.

property element_matrices_index_table

Return element matrices index table

property enum

Sorted ANSYS element numbers

global_applied_force()

Returns the applied force for each node.

Returns

applied_force – Applied force with size (n_nodes, n_dof). Result is sorted to correspond with the sorted global nodes array.

Return type

np.ndarray

property n_dof

Number of dofs per node

property n_elements

Number of elements in the file

property n_nodes

Number of nodes in the file

property neqv

Nodal equivalence table. This table equates the number used for storage to the actual node number.

property nnum

Sorted ANSYS node numbers

read_element(index, stress=True, mass=True, damping=True, stress_stiff=True, applied_force=True, newton_raphson=True, imaginary_load=True)

Read element by index

Parameters
  • index (int) – Element index. This is not the element number. Reference the element equivalency table for the actual element number.

  • stress (bool, optional) – Return the stress matrix entries if available.

  • mass (bool, optional) – Return the mass matrix entries if available.

  • damping (bool, optional) – Return the damping matrix entries if available.

  • stress_stiff (bool, optional) – Return the stress stiffening entries if available.

  • newton_raphson (bool, optional) – Return the newton raphson load entries if available.

  • applied_force (bool, optional) – Return the applied load vector if available.

  • imaginary_load (bool, optional) – Return the imaginary load vector if available.

Returns

  • dof_idx (np.ndarray) – DOF index table. This record specifies the DOF locations of this element matrix in relation to the global matrix. The index is calculated as (N-1)*NUMDOF+DOF, where N is the position number of the node in the nodal equivalence table and DOF is the DOF reference number given above

  • element_data (dict) – Dictionary containing the following entries for each of the corresponding inputs when the item is True. - ‘stress’ : stress matrix entries - ‘mass’ : mass matrix entries - ‘damping’ : damping matrix entries - ‘stress_stiff’ : stress stiffening matrix entries - ‘newton_raphson’ : newton rapson load vector - ‘applied_force’ : applied force vector - ‘imaginary_load’ : imaginary load vector

Notes

If the matrix is diagonal, the length of the records will be nmrow. If the matrix is unsymmetric, the length of the records will be nmrow*nmrow. If the matrix is symmetric, only the lower triangular terms are written and the length of the records will be (nmrow)*(nmrow+1)/2

Records are written relative to the dof_idx. The index is calculated as (N-1)*NUMDOF+DOF, where N is the position number of the node in the nodal equivalence table and DOF is the DOF reference number given by dof_idx.

read_element_matrix_header(f_index)

Read element matrix header

Parameters

f_indes (int) – Fortran index to the start of the element matrix header.

Notes

stkey - stiffness matrix key

0 - matrix not present 1 - matrix present

mkey - mass matrix key

0 - matirx not present 1 - matrix present

dkey - damping matrix key

0 - matrix not present 1 - matrix present

sskey - stress stiffening matrix key

0 - matrix not present 1 - matrix present

akey - applied load vector key

0 - vector not used 1 - vector used

nrkey - newton-raphson(restoring) load

0 - vector not used 1 - vector used

ikey - imaginary load vector key (for complex analyses)

0 - vector not used 1 - vector used

nmrow - numbers/columns in matrices.

If the number is negative, the matrices will be written in lower triangular form.

read_header()

Read standard emat file header