Frequency Response results from an analysis using On-Demand Expansion?

Andreas Rydin

Consider an analysis that was setup in Ansys Mechanical to use On-Demand Expansion and having multiple load steps defined. I want to create a text file of the frequence response (amplitude of acceleration in X direction) for some nodes. How can it be done with DPF?

Andreas Rydin

Here is a pyDPF script that will generate output files, for each node, the frequence response for each load step. The script assumes that the *rfrq, *mode and *rst files are located in the same folder (which would be the case if you're solving the modal+harmonic in the same system)

from ansys.dpf import core as dpf
import os,re
import glob

# Result Data
dpf.start_local_server(ansys_path=r'C:\Program Files\ANSYS Inc\v231')
res_path = r'D:\Temp\pyDPF\frf\expansion'
res_file = "file.rfrq"
resFile_exp = os.path.join(res_path, res_file)
ds = dpf.DataSources(resFile_exp)
mode_files = glob.glob(res_path + '/*.mode')
rst_files = glob.glob(res_path + '/*.rst')
data_source_up = dpf.DataSources()

for f in mode_files:
    numbers = re.findall(r'\d+', os.path.basename(f))
    data_source_up.set_domain_result_file_path(f, int(numbers[0]))
    print(int(numbers[0]), f)
if len(rst_files) > 0:
    for f in rst_files:
        numbers = re.findall(r'\d+', os.path.basename(f))
        data_source_up.add_file_path(f, 'rst', True, int(numbers[0]))
        print(int(numbers[0]), f)

ds.add_upstream(data_source_up)
my_model = dpf.Model(ds)

# Node Scopings
n_scoping = dpf.Scoping()
n_scoping.ids = [11091,11061]

#Time Scoping
ls = my_model.metadata.time_freq_support.time_frequencies
ls_scoping = ls.scoping.ids
timeList = dpf.operators.metadata.time_freq_provider(data_sources=ds).outputs.time_freq_support().time_frequencies.data
time_ids = list(range(1, len(timeList) + 1))

#Acceleration outputs
acc = dpf.operators.result.acceleration(data_sources=ds,time_scoping=time_ids,mesh_scoping=n_scoping)
my_model.metadata.release_streams()

for ns in n_scoping.ids:
    nScoping = dpf.Scoping()
    nScoping.ids = [ns]
    acc_rs = dpf.operators.scoping.rescope_fc(fields_container=acc,mesh_scoping=nScoping)
    acc_amp = dpf.operators.math.amplitude_fc(fields_container=acc_rs)
    #Get max/min from the acclacement scoping
    acc_max = dpf.operators.min_max.min_max_fc(fields_container=acc_amp)
    acc_max_output = acc_amp.outputs.fields_container()

    acc_Z = acc_max.outputs.field_max().data[:, 0]
    #Loop through the different load steps
    cnt = 0
    for ls in range(1,len(dpf.operators.metadata.time_freq_provider(data_sources=ds).outputs.time_freq_support().time_frequencies.scoping.ids)+1):
        freq_ls = dpf.operators.metadata.time_freq_provider(data_sources=ds).outputs.time_freq_support().time_frequencies.get_entity_data_by_id(ls)
        freq_ls_num = len(freq_ls)
        lcstring = 'Load Case #'+str(ls)
        y_value = acc_Z[cnt:cnt+freq_ls_num]
        freq_value = timeList[cnt:cnt+freq_ls_num]
        #Print to file
        fName = 'Acceleration_'+str(ns)+'_step_'+str(ls)+'.txt'
        with open(fName,'w+') as g:
            j = 0
            while j < len(freq_value):
                val = str(freq_value[j])+","+str(y_value[j])+"\n"
                g.write(val)
                j+=1
        cnt = cnt+freq_ls_num