PRESOL problem

[manarshhjot]

I am trying to get element wise solutions for the script using the PRESOL command but I receive empty arrays.

Here is the script that I have run

When I run the PRESOL command I don't receive an array but the results are empty

However, the nodal solutions are correct,

[mikerife]

Hi @manarshhjot can you give us more information? Can you share the cdb and material files? And the functions you defined elsewhere.

MIke

[manarshhjot]

Hello @mikerife ,
In the problem the material properties of every element need to be corrected individually after every iteration. The amount of correction depends on the element stress. The materials and cdb file are generated from another software (MIMICS). Initial material file has 10 different materials.

This is the initial material file.
NewMesh.txt
This is the cdb file used. I changed it to txt as cdb file can not be uploaded.
New_Mesh(cdb).txt

These are the functions that I am using

[mikerife]

Hi @manarshhjot Something went wrong creating the material model file. The E and Poissons ration values are all ~ 1E308. Also can you post your code as text and not an image. Mike

[manarshhjot]

Hello @mikerife,
I got the command to work. I had to add launch ANSYS with smp enabled.

mapdl = launch_mapdl(additional_switches='-smp')

I am able to run the command but the output is unusual.

I get 48848 elements in the result but I have just ~6000 elements in the imported mesh.

For the response to your querry, only density from the original material file is used. When assigning the material to elements, poisson's ratio is fixed at 0.25 and young's modulus is derived from the density using empirical relations. You can check the 'read_material_file' function.

MAIN CODE:

mapdl = launch_mapdl(additional_switches='-smp')
print(mapdl)

mapdl.clear()

mapdl.prep7()
no_ele = read_cdb('New_Mesh.cdb', mapdl)

print('Mesh file reading completed')

correction = np.ones(no_ele+1)
mapdl.prep7()
materials = read_materials_file('NewMesh.txt', mapdl, correction)

print('Material assigned')

mapdl.slashsolu()
print('Solution Started')
mapdl.outres('ALL','ALL')
mapdl.solve()
print('Solution completed')

FUNCTIONS:

def read_materials_file(file_name, mapdl, correction):
    read_file = open(file_name, 'r')
    mat_count = -1
    mat = []
    while True:
        line = read_file.readline()
        line_text = line.split(',')

        #### Creation of base material list ####
        if line_text[0] == 'MP':
            if int(line_text[2]) > mat_count:
                mat_count = mat_count + 1
                mat.append(material())

            if line_text[1] == 'DENS':
                mat[mat_count].den(float(line_text[3]))
                
        #### Assign element wise material in APDL ####
        if line[0:5] == 'MPCHG':
            line_text = line.split(',')
            mat_no = int(line_text[1])
            element_no = int(line_text[2])

            mapdl.mp('PRXY', element_no, 0.25) 
            mapdl.mp('DENS', element_no, mat[mat_no].den*correction[element_no])
            mapdl.mp('EX', element_no, d2ym(mat[mat_no].den))

        if not line:
            break

    return mat

def d2ym(rho): # kg/m3 to Pa
    rho=rho
    a = 0.1
    b = 1.79
    c = 0
    ym = (a*(rho**b)+c)*1000000
    return ym

def read_cdb(file_name, mapdl):
    mapdl.cdread("DB", file_name)
    elements = mapdl.db.elems
    return elements.max_num

class material:
    def __init__(self):
        pass

    def YM(self, x):
        self.YM = x

    def den(self, x):
        self.den = x

    def poi_ratio(self, x):
        self.poi_ratio = x

[mikerife]

Hi @manarshhjot Ok good to see your code is working now. Remember that the PRESOL command is listing the element nodal result. I.E. it is listing the stress result for each node in the element, for every element. If you want one value per element you will need to create an element table and list that. This will interpolate the element nodal values back to the centroid and report that value.

Mike

[mikerife]

Hi @manarshhjot Ok good to see your code is working now. Remember that the PRESOL command is listing the element nodal result. I.E. it is listing the stress result for each node in the element, for every element. If you want one value per element you will need to create an element table and list that. This will interpolate the element nodal values back to the centroid and report that value.

Mike
p.s. adding as new answer in order to mark question as answered.