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DAMASK_EICMD
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negative eigenvalues are not possible 

left/right Cauchy-Green Deformation Tensors are positive definit
https://de.wikipedia.org/wiki/Deformationsgradient
This commit is contained in:
Martin Diehl 2019-09-30 14:12:15 -07:00
parent d95a795e3b
commit 0e3b09adc1
1 changed files with 1 additions and 5 deletions
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python/damask/dadf5.py
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@ -575,10 +575,6 @@ class DADF5():
R_inv = np.transpose(np.matmul(U,Vh),(0,2,1)) # transposed rotation of polar decomposition R_inv = np.transpose(np.matmul(U,Vh),(0,2,1)) # transposed rotation of polar decomposition
U = np.matmul(R_inv,defgrad['data']) # F = RU U = np.matmul(R_inv,defgrad['data']) # F = RU
(D,V) = np.linalg.eigh((U+np.transpose(U,(0,2,1)))*.5) # eigen decomposition (of symmetric(ed) matrix) (D,V) = np.linalg.eigh((U+np.transpose(U,(0,2,1)))*.5) # eigen decomposition (of symmetric(ed) matrix)
neg = np.where(D < 0.0) # find negative eigenvalues ...
D[neg[0],neg[1]] = D[neg[0],neg[1]]* -1 # ... flip value ...
V[neg[0],:,neg[1]] = V[neg[0],:,neg[1]]* -1 # ... and vector
d = operator['V#ln'](D) d = operator['V#ln'](D)
a = np.matmul(V,np.einsum('ij,ikj->ijk',d,V)) a = np.matmul(V,np.einsum('ij,ikj->ijk',d,V))
@ -589,7 +585,7 @@ class DADF5():
'meta' : { 'meta' : {
'Unit' : defgrad['meta']['Unit'], 'Unit' : defgrad['meta']['Unit'],
'Description' : 'Strain tensor ln(V){} ({})'.format(defgrad['label'],defgrad['meta']['Description']), 'Description' : 'Strain tensor ln(V){} ({})'.format(defgrad['label'],defgrad['meta']['Description']),
'Creator' : 'dadf5.py:add_deviator v{}'.format(version) 'Creator' : 'dadf5.py:add_strain_tensor v{}'.format(version)
} }
} }