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DAMASK_EICMD
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simple strain calculation for DADF5 

further enhancement requires to give optional arguments to
add_genericpontwise
This commit is contained in:
Martin Diehl 2019-07-06 21:41:29 -07:00
parent 18f00cb8df
commit b6bb8a4650
2 changed files with 31 additions and 4 deletions
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6
processing/post/addStrainTensors.py
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@ -136,9 +136,9 @@ for name in filenames:
for column in items['tensor']['column']: # loop over all requested defgrads
F = np.array(list(map(float,table.data[column:column+items['tensor']['dim']])),'d').reshape(items['tensor']['shape'])
(U,S,Vh) = np.linalg.svd(F) # singular value decomposition
R = np.dot(U,Vh) # rotation of polar decomposition
stretch['U'] = np.dot(np.linalg.inv(R),F) # F = RU
stretch['V'] = np.dot(F,np.linalg.inv(R)) # F = VR
R_inv = np.linalg.inv(np.dot(U,Vh)) # inverse rotation of polar decomposition
stretch['U'] = np.dot(R_inv,F) # F = RU
stretch['V'] = np.dot(F,R_inv) # F = VR
for theStretch in stretches:
stretch[theStretch] = np.where(abs(stretch[theStretch]) < 1e-12, 0, stretch[theStretch]) # kill nasty noisy data

29
python/damask/dadf5.py
View File

@ -224,7 +224,7 @@ class DADF5():
def add_determinant(self,a):
"""Adds the determinan of a tensor"""
"""Adds the determinant of a tensor"""
# ToDo: The output unit should be the input unit
args = [{'label':a,'shape':[3,3],'unit':None}]
result = {'label':'det({})'.format(a),
@ -233,6 +233,33 @@ class DADF5():
self.add_generic_pointwise(np.linalg.det,args,result)
def add_strain_tensors(self,defgrad='F'):
"""Adds a strain definition"""
def strain(defgrad):
(U,S,Vh) = np.linalg.svd(defgrad) # singular value decomposition
R_inv = np.linalg.inv(np.dot(U,Vh)) # inverse rotation of polar decomposition
U = np.dot(R_inv,defgrad) # F = RU
U = np.where(abs(U) < 1e-12, 0, U) # kill nasty noisy data
(D,V) = np.linalg.eig(U) # eigen decomposition (of symmetric matrix)
neg = np.where(D < 0.0) # find negative eigenvalues ...
D[neg] *= -1. # ... flip value ...
V[:,neg] *= -1. # ... and vector
for i,eigval in enumerate(D):
if np.dot(V[:,i],V[:,(i+1)%3]) != 0.0: # check each vector for orthogonality
V[:,(i+1)%3] = np.cross(V[:,(i+2)%3],V[:,i]) # correct next vector
V[:,(i+1)%3] /= np.sqrt(np.dot(V[:,(i+1)%3],V[:,(i+1)%3].conj())) # and renormalize (hyperphobic?)
d = np.log(D) # operate on eigenvalues of U o r V
return np.dot(V,np.dot(np.diag(d),V.T)).real # build tensor back from eigenvalue/vector basis
# ToDo: The output unit should be the input unit
args = [{'label':defgrad,'shape':[3,3],'unit':None}]
result = {'label':'strain({})'.format(defgrad),
'unit':'-',
'Description': 'strain (ln(V)) of a deformation gradient'}
self.add_generic_pointwise(strain,args,result)
def get_fitting(self,data):
groups = []