Is it possible to convert the Nastran .op4 file to Ansys readable file.?

Naveen Kumar Begari

Hi @AKD-Scripting-Team

I have .op4 (Nastran) file, want to open in Ansys it could be in csv or .cdb formats
If possible through scripts any suggestions would be helpful

Regards
Naveen Kumar B

Rajesh Meena

Hi @Naveen Kumar Begari ,

Please have a look at this:

https://pynastran-git.readthedocs.io/en/latest/quick_start/features.html#op4-reader-writer

M

or here: https://pyyeti.readthedocs.io/en/latest/tutorials/op4.html

Naveen Kumar Begari

Hi @Rajesh Meena & @M Thanks for your quick response.

With the help of those websites, I created this script yesterday:

`
import numpy as np
from pyyeti.nastran import op4
file_path = "nastran.op4"
matrices = op4.read(file_path, justmatrix=True)
print("Available Matrices:", matrices.keys())

matrix_name = list(matrices.keys())[0]
matrix_data = matrices[matrix_name]

print(f"Matrix {matrix_name}:")
print(matrix_data)
matrix_data = matrices[matrix_name]
if isinstance(matrix_data, tuple):
matrix_data = matrix_data[0] # Extract only the numerical matrix
matrix_data = np.atleast_2d(matrix_data)
np.savetxt(f"{matrix_name}.csv", matrix_data, fmt="%.6f", delimiter=" ")
`

but it doesn't work well as expected

Pernelle Marone-Hitz

Hi @Naveen Kumar Begari , this is not enough information for us to help. What is the expected behavior ? What is not working ? Do you have an error message ?

Naveen Kumar Begari

@Pernelle Marone-Hitz how can I read the .csv file or any other supported file for Ansys which was generated by Nastran .op4 file.

No error message it is getting.

Pernelle Marone-Hitz

@Naveen Kumar Begari What I meant if, from the code you shared, what is not working? Also tagging @Pierre Thieffry who might have done this in the past.

Pierre Thieffry

@Naveen Kumar Begari what do you want to do with the matrices from the op4 file?

Naveen Kumar Begari

@Pierre Thieffry

In Nastran, the .op4 file contains matrix data used in finite element analysis (FEA). The element matrix is used for several reasons:

Structural Stiffness – It represents the stiffness contribution of individual elements in the global system.

Mass and Damping – It stores mass and damping matrices for dynamic analysis.

Load Influence – Helps in calculating response due to applied loads.

Modal Analysis – Used to compute eigenvalues and eigenvectors for vibration analysis.