def addFaceTraction(order, assembler, load):
# Create the surface traction
aux = TACS.AuxElements()
# Get the element node locations
nelems = assembler.getNumElements()
for i in range(nelems):
# Get the information about the given element
elem, Xpt, vars0, dvars, ddvars = assembler.getElementData(i)
# Loop over the nodes and create the traction forces in the
# x/y/z directions
nnodes = order*order
tx = np.zeros(nnodes, dtype=TACS.dtype)
ty = np.zeros(nnodes, dtype=TACS.dtype)
tz = np.zeros(nnodes, dtype=TACS.dtype)
# Set the components of the surface traction
for j in range(nnodes):
x = Xpt[3*j]
y = Xpt[3*j+1]
z = Xpt[3*j+2]
theta = -R*np.arctan2(y, x)
p = -load*np.sin(beta*z)*np.sin(alpha*theta)
tx[j] = p*Xpt[3*j]/R
ty[j] = p*Xpt[3*j+1]/R
tz[j] = 0.0
trac = elements.ShellTraction(order, tx, ty, tz)
aux.addElement(i, trac)
return aux
def createAuxElements(self, assembler, order=3):
aux = TACS.AuxElements()
tx = np.zeros(order * order)
ty = np.zeros(order * order)
tz = -np.ones(order * order)
trac = elements.ShellTraction(order, tx, ty, tz)
for i in range(assembler.getNumElements()):
aux.addElement(i, trac)
return aux
def computeTractionLoad(name, forest, assembler, trac):
"""
Add a surface traction to all quadrants or octants that touch a face or edge with
the given name. The assembler must be created from the provided forest. The list
trac must have a traction for each face (6) for octants or each edge (4) for
quadrants.
Note: This code uses the fact that the getOctsWithName or getQuadsWithName returns
the local face or edge index touching the surface or edge in the info member.
Args:
name (str): Name of the surface where the traction will be added
forest (QuadForest or OctForest): Forest for the finite-element mesh
assembler (Assembler): TACSAssembler object for the finite-element problem
trac (list): List of tractions, one for each possible face/edge orientation
Returns:
Vec: A force vector containing the traction
"""
if isinstance(forest, TMR.OctForest):
octants = forest.getOctants()
face_octs = forest.getOctsWithName(name)
elif isinstance(forest, TMR.QuadForest):
octants = forest.getQuadrants()
face_octs = forest.getQuadsWithName(name)
# Create the force vector and zero the variables in the assembler
force = assembler.createVec()
assembler.zeroVariables()
# Create the auxiliary element class
aux = TACS.AuxElements()
for i in range(len(face_octs)):
index = face_octs[i].tag
if index is not None:
aux.addElement(index, trac[face_octs[i].info])
# Keep auxiliary elements already set in the assembler
# aux_tmp = assembler.getAuxElements()
assembler.setAuxElements(aux)
# Compute the residual where force = -residual
assembler.assembleRes(force)
force.scale(-1.0)
# Reset the auxiliary elements
assembler.setAuxElements(None) # (aux_tmp)
return force
def addFaceTraction(order, forest, attr, assembler, tr):
trac = []
for findex in range(6):
trac.append(elements.Traction3D(order, findex, tr[0], tr[1], tr[2]))
# Retrieve octants from the forest
octants = forest.getOctants()
face_octs = forest.getOctsWithAttribute(attr)
aux = TACS.AuxElements()
for i in range(len(face_octs)):
aux.addElement(face_octs[i].tag, trac[face_octs[i].info])
return aux
def rectangular_domain(nx, ny, Ly=100.0):
# Set the y-dimension based on a unit aspect ratio
Lx = (nx*Ly)/ny
# Compute the total area
area = Lx*Ly
# Set the number of elements/nodes in the problem
nnodes = (nx+1)*(ny+1)
nelems = nx*ny
nodes = np.arange(nnodes).reshape((nx+1, ny+1))
# Set the node locations
xpts = np.zeros((nnodes, 3))
x = np.linspace(0, Lx, nx+1)
y = np.linspace(0, Ly, ny+1)
for j in range(ny+1):
for i in range(nx+1):
xpts[nodes[i,j],0] = x[i]
xpts[nodes[i,j],1] = y[j]
# Set the connectivity and create the corresponding elements
conn = np.zeros((nelems, 4), dtype=np.intc)
for j in range(ny):
for i in range(nx):
# Append the first set of nodes
n = i + nx*j
conn[n,0] = nodes[i, j]
conn[n,1] = nodes[i+1, j]
conn[n,2] = nodes[i, j+1]
conn[n,3] = nodes[i+1, j+1]
bcs = np.array(nodes[0,:], dtype=np.intc)
# Create the tractions and add them to the surface
surf = 1 # The u=1 positive surface
tx = np.zeros(2)
ty = -100*np.ones(2)
trac = elements.PSQuadTraction(surf, tx, ty)
# Create the auxiliary element class
aux = TACS.AuxElements()
for j in range(int(ny/8)):
num = nx-1 + nx*j
aux.addElement(num, trac)
return xpts, conn, bcs, aux, area
def addEdgeTraction(order, forest, attr, assembler, tr):
trac = []
for findex in range(4):
trac.append(elements.PSQuadTraction(findex, tr[0]*np.ones(2), \
tr[1]*np.ones(2)))
# Retrieve octants from the forest
quadrants = forest.getQuadrants()
edge_quads = forest.getQuadsWithAttribute(attr)
aux = TACS.AuxElements()
for i in range(len(edge_quads)):
index = quadrants.findIndex(edge_quads[i])
if index is not None:
aux.addElement(index, trac[edge_quads[i].tag])
return aux
def addFaceTraction(order, forest, assembler):
# Get the quadrilaterals of interest
quads = forest.getQuadsWithName('traction')
# Create the surface traction
aux = TACS.AuxElements()
# Loop over the nodes and create the traction forces in the x/y/z
# directions
nnodes = order
tx = np.zeros(nnodes, dtype=TACS.dtype)
ty = np.zeros(nnodes, dtype=TACS.dtype)
ty[:] = 10.0
# Create the shell traction
surf = 1
trac = elements.PSQuadTraction(surf, tx, ty)
for q in quads:
aux.addElement(q.tag, trac)
return aux
def addFaceTraction(order, assembler):
# Create the surface traction
aux = TACS.AuxElements()
# Get the element node locations
nelems = assembler.getNumElements()
# Loop over the nodes and create the traction forces in the x/y/z
# directions
nnodes = order * order
tx = np.zeros(nnodes, dtype=TACS.dtype)
ty = np.zeros(nnodes, dtype=TACS.dtype)
tz = np.zeros(nnodes, dtype=TACS.dtype)
tz[:] = 5.0
# Create the shell traction
trac = elements.ShellTraction(order, tx, ty, tz)
for i in range(nelems):
aux.addElement(i, trac)
return aux
def createAssembler(m=5.0, c=0.5, k=5.0, u0=-0.5, udot0=1.0, pc=None):
num_disps = 1
num_nodes = 1
# Spring element
#spr = SpringMassDamper(num_disps, num_nodes, m, c, k)
dspr = PSPACE.PySMD(m, c, k, u0, udot0)
sprcb = SMDUpdate(dspr)
sspr = PSPACE.PyStochasticElement(dspr, pc, sprcb)
dforce = ForcingElement(num_disps, num_nodes, amplitude=1.0, omega=10.0)
forcecb = ForceUpdate(dforce)
sforce = PSPACE.PyStochasticElement(dforce, pc, forcecb)
ndof_per_node = 1 * pc.getNumBasisTerms()
num_owned_nodes = 1
num_elems = 1
# Add user-defined element to TACS
comm = MPI.COMM_WORLD
assembler = TACS.Assembler.create(comm, ndof_per_node, num_owned_nodes,
num_elems)
ptr = np.array([0, 1], dtype=np.intc)
conn = np.array([0], dtype=np.intc)
assembler.setElementConnectivity(ptr, conn)
# Set elements
assembler.setElements([sspr])
# set Auxiliary elements
aux = TACS.AuxElements()
aux.addElement(0, sforce)
assembler.setAuxElements(aux)
assembler.initialize()
return assembler
elem = elements.MITCShell(order, stiff)
return elem
def cylinderEvalTraction(Xp):
x = Xp[0]
y = Xp[1]
z = Xp[2]
theta = -R * np.arctan2(y, x)
p = -load * np.sin(beta * z) * np.sin(alpha * theta)
return [p * x / R, p * y / R, 0.0]
def addFaceTraction(case, order, assembler, load):
# Create the surface traction
aux = TACS.AuxElements()
# Get the element node locations
nelems = assembler.getNumElements()
if case == 'cylinder':
trac = elements.ShellTraction(order, evalf=cylinderEvalTraction)
for i in range(nelems):
aux.addElement(i, trac)
elif case == 'disk':
nnodes = order * order
tx = np.zeros(nnodes, dtype=TACS.dtype)
ty = np.zeros(nnodes, dtype=TACS.dtype)
tz = np.zeros(nnodes, dtype=TACS.dtype)
tz[:] = load
def bracket_domain(nb, nc, Lx=100.0):
# Compute the total area
area = 0.64 * Lx**2
# The total number of elements along one direction
nx = nb + nc
# Allocate all of the nodes (including blanked nodes)
nodes = np.ones((nx + 1, nx + 1), dtype=np.int)
nodes[nb + 1:, nb + 1:] = -1
# Allocate all of the elements (including blanked elements)
elems = np.ones((nx, nx), dtype=np.int)
elems[nb:, nb:] = -1
# Number the nodes
index = 0
for j in range(nx + 1):
for i in range(nx + 1):
if nodes[i, j] >= 0:
nodes[i, j] = index
index += 1
# Set the element numbering
index = 0
for j in range(nx):
for i in range(nx):
if elems[i, j] >= 0:
elems[i, j] = index
index += 1
# Set the boundary conditions
bcs = np.array(nodes[:(nb + 1), -1], dtype=np.intc)
# Compute the number of nodes and elements
n = (nb + 1)**2 + 2 * (nb + 1) * nc
ne = nb**2 + 2 * nb * nc
# Allocate the arrays
conn = np.zeros((ne, 4), dtype=np.intc)
xpts = np.zeros((n, 3))
# Set the node locations
for j in range(nx + 1):
for i in range(nx + 1):
if nodes[i, j] >= 0:
xpts[nodes[i, j], 0] = (Lx * i) / nx
xpts[nodes[i, j], 1] = (Lx * j) / nx
# Set the nodal connectivity
for j in range(nx):
for i in range(nx):
if elems[i, j] >= 0:
conn[elems[i, j], 0] = nodes[i, j]
conn[elems[i, j], 1] = nodes[i + 1, j]
conn[elems[i, j], 2] = nodes[i, j + 1]
conn[elems[i, j], 3] = nodes[i + 1, j + 1]
# Create the tractions and add them to the surface
surf = 1 # The u=1 positive surface
tx = np.zeros(2)
ty = 100 * np.ones(2)
trac = elements.PSQuadTraction(surf, tx, ty)
# Create the auxiliary element class
aux = TACS.AuxElements()
for j in range(int(5 * nb / 6), nb):
aux.addElement(elems[-1, j], trac)
return xpts, conn, bcs, aux, area
def createAssembler(tacs_comm):
# Set constitutive properties
rho = 4540.0 # density, kg/m^3
E = 118e9 # elastic modulus, Pa 118e9
nu = 0.325 # poisson's ratio
ys = 1050e6 # yield stress, Pa
kappa = 6.89
specific_heat = 463.0
# Set the back-pressure for the traction load
pb = 654.9 #10.0 # A value for the surface pressure
# Load in the mesh
mesh = TACS.MeshLoader(tacs_comm)
mesh.scanBDFFile('tacs_aero.bdf')
# Get the number of components set in the mesh. Each component is
num_components = mesh.getNumComponents()
# Each domain consists of the union of two components. The component
# corresponding to the surface traction and the component corresponding
# to remaining plate elements. There is one design variable associated
# with each domain that shares a common (x,z) coordinate
num_domains = num_components // 2
# Create the constitutvie propertes and model
props_plate = constitutive.MaterialProperties(rho=rho,
specific_heat=specific_heat,
kappp=kappa,
E=E,
nu=nu,
ys=ys)
# Create the basis class
basis = elements.LinearHexaBasis()
element_list = []
for k in range(num_domains):
# Create the elements in an element list
con = constitutive.SolidConstitutive(props_plate, t=1.0, tNum=k)
phys_model = elements.LinearThermoelasticity3D(con)
# Create the element
element_list.append(elements.Element3D(phys_model, basis))
varsPerNode = phys_model.getVarsPerNode()
# Set the face index for the side of the element where the traction
# will be applied. The face indices are as follows for the hexahedral
# basis class:
# -x: 0, +x: 1, -y: 2, +y: 3, -z: 4, +z: 5
faceIndex = 4
# Set the wedge angle - 5 degrees
theta = np.radians(5.0)
# Compute the outward normal components for the face
nx = np.sin(theta)
nz = -np.cos(theta)
# Set the traction components
tr = [-pb * nx, 0.0, -pb * nz, 0.0]
# Create the traction class
traction = elements.Traction3D(varsPerNode, faceIndex, basis, tr)
# Set the elements corresponding to each component number
num_components = mesh.getNumComponents()
for k in range(num_components):
mesh.setElement(k, element_list[k % num_domains])
# Create the assembler object
assembler = mesh.createTACS(varsPerNode)
# Set the traction load into the assembler object
aux = TACS.AuxElements(assembler)
for k in range(num_domains, num_components):
mesh.addAuxElement(aux, k, traction)
assembler.setAuxElements(aux)
return assembler, num_domains
