using python library ansys.mapdl adn ansys.mapdl.reader extract equivalent stress

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Erubus
Erubus Member Posts: 4
First Comment

I used the following code to extract the equivalent stress and displacement. Currently, the displacement can correspond to the workbench data, but the equivalent stress is not. May I ask if there is a problem with my extraction code? The stress code is as follows:

from ansys.mapdl import reader as pymapdl_reader
from ansys.mapdl.reader import rst
import numpy as np
import json
import argparse


def extract_stress(self: rst.Result, rsets=None):
    if rsets is None:
        rsets = range(self.nsets)
    elif isinstance(rsets, int):
        rsets = [rsets]
    elif not isinstance(rsets, rst.Iterable):
        raise TypeError("rsets must be an iterable like [0, 1, 2] or range(3)")

    stress_data = {}
    for i in rsets:
        max_sigma1 = max_sigma2 = max_sigma3 = max_sint = max_seqv = float('-inf')
        enum, element_stresses, enode = self.element_stress(i, principal=True)

        if element_stresses is None or not any(np.isfinite(stress).any() for stress in element_stresses):
            print(f"No valid stress data available for result set {i}.")
            continue

        for stress_array in element_stresses:
            if np.isnan(stress_array).all():
                continue

            max_sigma1 = max(max_sigma1, np.max(stress_array[:, 0]))
            max_sigma2 = max(max_sigma2, np.max(stress_array[:, 1]))
            max_sigma3 = max(max_sigma3, np.max(stress_array[:, 2]))
            max_sint = max(max_sint, np.max(stress_array[:, 3]))
            max_seqv = max(max_seqv, np.max(stress_array[:, 4]))

        # 存储到字典
        stress_data[i] = {
            "max_sigma1": max_sigma1,
            "max_sigma2": max_sigma2,
            "max_sigma3": max_sigma3,
            "max_sint": max_sint,
            "max_seqv": max_seqv
        }

        # export stress picture
        for comp in ["X", "Y", "Z", "XY", "XZ", "YZ"]:
            self.plot_nodal_stress(
                i,
                comp=comp,
                screenshot='stress_{}_{}.png'.format(i, comp),
                show_displacement=True,
                window_size=[800, 600],
                interactive=False
            )

    # export json
    with open('stress.json', 'w') as json_file:
        json.dump(stress_data, json_file, indent=4)

    return


if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument("--input",
                        required=True,
                        help="Ansys result file path.")
    args = parser.parse_args()
    result = pymapdl_reader.read_binary(args.input)
    extract_stress(result)

According to the element_stress interface description, to extract VON: von Mises requires principal=True, and then SIGMA1, SIGMA2, SIGMA3, SINT, SEQV will be returned. I now use the above code to get the maximum stress, but the value obtained is inconsistent with the maximum stress obtained by Ansys Workbench. , where is the problem? Looking forward to reply.

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