from collections import defaultdict
from pyNastran.bdf.bdf import read_bdf, BDF, FORCE, PLOAD4
[docs]
def force_to_pressure(bdf_filename, bdf_filename_out=None):
"""converts FORCE cards to PLOAD4s for a shell model"""
if isinstance(bdf_filename, BDF):
model = bdf_filename
else:
model = read_bdf(bdf_filename, validate=True, xref=False, punch=False,
encoding=None, log=None, debug=True,
mode='msc')
#if 0:
##card_types = ['CQUAD4', 'CTRIA3']
#card_ids_map = model.get_card_ids_by_card_types(card_types=None,
#reset_type_to_slot_map=False,
#stop_on_missing_card=False)
#for eid in card_ids_map['CQUAD4']:
#elem = model.elements[eid]
##for nid in elem.node_ids:
##raise NotImplementedError(elem)
#for eid in card_ids_map['CTRIA3']:
#elem = model.elements[eid]
#raise NotImplementedError(elem)
nid_elem_count = defaultdict(int)
nid_elem_map = defaultdict(list)
for eid, elem in model.elements.items():
for nid in elem.nodes:
nid_elem_count[nid] += 1
nid_elem_map[nid].append(eid)
#model.cross_reference()
forces = defaultdict(float)
for load_id, load in model.loads.items():
for loadi in loads:
if loadi.type == 'FORCE':
loadi = FORCE(sid, node, cid, mag, xyz)
loadi.get
#if load.node_id not in nids:
#continue
if load.Cid() != 0:
cp = load.cid
forcei = load.mag * cp.transform_vector_to_global(load.xyz) * scale
raise NotImplementedError()
else:
forcei = load.mag * load.xyz * scale
elem_count = nid_elem_count[load.node]
f /= elem_count
for eid in nid_elem_map:
forces[eid] += forcei
#node = self.Node(load.node_id)
#r = xyz[node.nid] - p
#m = cross(r, f)
#F += f
#M += m
else:
raise NotImplementedError(loadi)
#pressures = {}
model.cross_reference()
model.loads = {}
add_methods = model._add_methods
with open('pressures.out', 'w') as pressure_file:
for eid, press in forces.items():
eids = [eid]
forcei = forces[eid]
elem = model.elements[eid]
area = elem.Area()
pressures = [pressure, pressure, pressure, pressure]
pload4 = PLOAD4(sid, eids, pressures,
g1=None, g34=None, cid=0, nvector=None,
surf_or_line='SURF', line_load_dir='NORM', comment='')
#pressure_file.write(pload4.write_card(size=8, is_double=False))
add_methods._add_load_object(pload4)
if bdf_filename_out:
model.write_bdf(bdf_filename_out)
return model