"""
defines:
- cart3d = nastran_to_cart3d(bdf, log=None, debug=False)
- nastran_to_cart3d_filename(bdf_filename, cart3d_filename,
log=None, debug=False)
"""
from numpy import zeros, arange, array, array_equal
import numpy as np
from pyNastran.bdf.bdf import BDF
from pyNastran.converters.cart3d.cart3d import Cart3D
LINE_ELEMENTS = ['CBAR', 'CBEAM', 'CROD', 'CELAS1', 'CELAS2', 'CELAS3', 'CELAS4']
[docs]def nastran_to_cart3d(bdf, log=None, debug=False):
"""
Converts a Nastran BDF() object to a Cart3D() object.
Parameters
----------
bdf : BDF()
a BDF object
log : log; default=None -> dummyLogger
a logger object
debug : bool; default=False
True/False (used if log is not defined)
Returns
-------
cart3d : Cart3D()
a Cart3D object
"""
cart3d = Cart3D(log=log, debug=debug)
nnodes = len(bdf.nodes)
nelements = 0
if 'CTRIA3' in bdf.card_count:
nelements += bdf.card_count['CTRIA3']
if 'CQUAD4' in bdf.card_count:
nelements += bdf.card_count['CQUAD4'] * 2
nodes = zeros((nnodes, 3), 'float64')
elements = zeros((nelements, 3), 'int32')
regions = zeros(nelements, 'int32')
nids = array(list(bdf.nodes.keys()), dtype='int32')
nids_expected = arange(1, len(nids) + 1)
if array_equal(nids, nids_expected):
_store_sequential_nodes(bdf, nodes, elements, regions)
else:
#print('not equal...')
#i = 0
nid_map = {}
for node_id, node in sorted(bdf.nodes.items()):
i = np.where(nids == node_id)[0][0]
nodes[i, :] = node.get_position()
nid_map[node_id] = i + 1
#print('nid_map =', nid_map)
i = 0
for unused_element_id, element in sorted(bdf.elements.items()):
if element.type == 'CTRIA3':
nids = element.node_ids
elements[i, :] = [nid_map[nid] for nid in nids]
regions[i] = element.material_ids[0]
elif element.type == 'CQUAD4':
nids = element.node_ids
quad = [nid_map[nid] for nid in nids]
mid = element.material_ids[0]
# TODO: splits on edge 1-3, not the max angle
# since we're just comparing the models, it doesn't matter
elements[i, :] = [quad[0], quad[1], quad[2]]
regions[i] = mid
i += 1
elements[i, :] = [quad[0], quad[2], quad[3]]
regions[i] = mid
elif element.type in LINE_ELEMENTS:
continue
else:
raise NotImplementedError(element.type)
i += 1
assert elements.min() > 0, elements
cart3d.nodes = nodes
cart3d.elements = elements - 1
cart3d.regions = regions
return cart3d
def _store_sequential_nodes(bdf, nodes, elements, regions):
# we don't need to renumber the nodes
# so we don't need to make an nid_map
i = 0
for node_id, node in sorted(bdf.nodes.items()):
nodes[i, :] = node.get_position()
i += 1
j = 0
for unused_element_id, element in sorted(bdf.elements.items()):
if element.type == 'CTRIA3':
nids = element.node_ids
elements[j, :] = nids
regions[j] = element.Mid()
elif element.type in LINE_ELEMENTS:
pass
#elif element.type == 'CQUAD4':
#nids = element.node_ids
#elements[i, :] = nids
#regions[i] = element.Mid()
else:
raise NotImplementedError(element.type)
j += 1
[docs]def nastran_to_cart3d_filename(bdf_filename, cart3d_filename, log=None, debug=False):
"""
Creates a Nastran BDF from a Cart3D file.
Parameters
----------
bdf_filename : str
the path to the bdf file
cart3d_filename : str
the path to the cart3d output file
log : log; default=None -> dummyLogger
a logger object
debug : bool; default=False
True/False (used if log is not defined)
"""
model = BDF(log=log, debug=debug)
model.read_bdf(bdf_filename)
nnodes = len(model.nodes)
nelements = len(model.elements)
with open(cart3d_filename, 'w', encoding='utf8') as cart3d:
cart3d.write('%s %s\n' % (nnodes, nelements))
node_id_shift = {}
i = 1
for node_id, node in sorted(model.nodes.items()):
node_id_shift[node_id] = i
x, y, z = node.get_position()
cart3d.write('%s %s %s\n' % (x, y, z))
i += 1
mids = ''
j = 0
for unused_element_id, element in sorted(model.elements.items()):
if element.type in ['CQUADR', 'CQUAD4', 'CONM2']:
print('element type=%s is not supported' % element.type)
continue
assert element.type in ['CTRIA3', 'CTRIAR'], element.type
out = element.node_ids
try:
n1, n2, n3 = out
except Exception:
print("type =", element.type)
raise
n1 = node_id_shift[n1]
n2 = node_id_shift[n2]
n3 = node_id_shift[n3]
mid = element.Mid()
cart3d.write('%i %i %i\n' % (n1, n2, n3))
mids += '%i ' % mid
if j != 0 and j % 20 == 0:
mids += '\n'
j += 1
cart3d.write(mids + '\n')