diff --git a/python/damask/mechanics.py b/python/damask/mechanics.py index 76c7ae13b..aef6b49ef 100644 --- a/python/damask/mechanics.py +++ b/python/damask/mechanics.py @@ -14,7 +14,7 @@ from . import _rotation def deformation_Cauchy_Green_left(F: _np.ndarray) -> _np.ndarray: - """ + r""" Calculate left Cauchy-Green deformation tensor (Finger deformation tensor). Parameters @@ -27,12 +27,18 @@ def deformation_Cauchy_Green_left(F: _np.ndarray) -> _np.ndarray: B : numpy.ndarray, shape (...,3,3) Left Cauchy-Green deformation tensor. + Notes + ----- + .. math:: + + \vb{B} = \vb{F} \vb{F}^\text{T} + """ return _np.matmul(F,_tensor.transpose(F)) def deformation_Cauchy_Green_right(F: _np.ndarray) -> _np.ndarray: - """ + r""" Calculate right Cauchy-Green deformation tensor. Parameters @@ -45,12 +51,18 @@ def deformation_Cauchy_Green_right(F: _np.ndarray) -> _np.ndarray: C : numpy.ndarray, shape (...,3,3) Right Cauchy-Green deformation tensor. + Notes + ----- + .. math:: + + \vb{C} = \vb{F}^\text{T} \vb{F} + """ return _np.matmul(_tensor.transpose(F),F) def equivalent_strain_Mises(epsilon: _np.ndarray) -> _np.ndarray: - """ + r""" Calculate the Mises equivalent of a strain tensor. Parameters @@ -63,12 +75,23 @@ def equivalent_strain_Mises(epsilon: _np.ndarray) -> _np.ndarray: epsilon_vM : numpy.ndarray, shape (...) Von Mises equivalent strain of epsilon. + Notes + ----- + The von Mises equivalent of a strain tensor is defined as: + + .. math:: + + \epsilon_\text{vM} = \sqrt{2/3 \epsilon^\prime_{ij} \epsilon^\prime_{ij}} + + where :math:`\vb*{\epsilon}^\prime` is the deviatoric part + of the strain tensor. + """ return _equivalent_Mises(epsilon,2.0/3.0) def equivalent_stress_Mises(sigma: _np.ndarray) -> _np.ndarray: - """ + r""" Calculate the Mises equivalent of a stress tensor. Parameters @@ -81,6 +104,17 @@ def equivalent_stress_Mises(sigma: _np.ndarray) -> _np.ndarray: sigma_vM : numpy.ndarray, shape (...) Von Mises equivalent stress of sigma. + Notes + ----- + The von Mises equivalent of a stress tensor is defined as: + + .. math:: + + \sigma_\text{vM} = \sqrt{3/2 \sigma^\prime_{ij} \sigma^\prime_{ij}} + + where :math:`\vb*{\sigma}^\prime` is the deviatoric part + of the stress tensor. + """ return _equivalent_Mises(sigma,3.0/2.0) @@ -105,7 +139,7 @@ def maximum_shear(T_sym: _np.ndarray) -> _np.ndarray: def rotation(T: _np.ndarray) -> _rotation.Rotation: - """ + r""" Calculate the rotational part of a tensor. Parameters @@ -118,6 +152,17 @@ def rotation(T: _np.ndarray) -> _rotation.Rotation: R : damask.Rotation, shape (...) Rotational part of the vector. + Notes + ----- + The rotational part is calculated from the polar decomposition: + + .. math:: + + \vb{R} = \vb{T} \vb{U}^{-1} = \vb{V}^{-1} \vb{T} + + where :math:`\vb{V}` and :math:`\vb{U}` are the left + and right stretch tensor, respectively. + """ return _rotation.Rotation.from_matrix(_polar_decomposition(T,'R')[0]) @@ -212,7 +257,7 @@ def stress_second_Piola_Kirchhoff(P: _np.ndarray, def stretch_left(T: _np.ndarray) -> _np.ndarray: - """ + r""" Calculate left stretch of a tensor. Parameters @@ -225,12 +270,23 @@ def stretch_left(T: _np.ndarray) -> _np.ndarray: V : numpy.ndarray, shape (...,3,3) Left stretch tensor from Polar decomposition of T. + Notes + ----- + The left stretch tensor is calculated from the + polar decomposition: + + .. math:: + + \vb{V} = \vb{T} \vb{R}^\text{T} + + where :math:`\vb{R}` is a rotation. + """ return _polar_decomposition(T,'V')[0] def stretch_right(T: _np.ndarray) -> _np.ndarray: - """ + r""" Calculate right stretch of a tensor. Parameters @@ -243,6 +299,17 @@ def stretch_right(T: _np.ndarray) -> _np.ndarray: U : numpy.ndarray, shape (...,3,3) Left stretch tensor from Polar decomposition of T. + Notes + ----- + The right stretch tensor is calculated from the + polar decomposition: + + .. math:: + + \vb{U} = \vb{R}^\text{T} \vb{T} + + where :math:`\vb{R}` is a rotation. + """ return _polar_decomposition(T,'U')[0] @@ -260,6 +327,11 @@ def _polar_decomposition(T: _np.ndarray, Requested outputs: ‘R’ for the rotation tensor, ‘V’ for left stretch tensor, and ‘U’ for right stretch tensor. + Returns + ------- + VRU : tuple of numpy.ndarray, shape (...,3,3) + Requested components of the singular value decomposition. + """ u, _, vh = _np.linalg.svd(T) R = _np.einsum('...ij,...jk',u,vh) @@ -290,6 +362,11 @@ def _equivalent_Mises(T_sym: _np.ndarray, s : float Scaling factor (2/3 for strain, 3/2 for stress). + Returns + ------- + eq : numpy.ndarray, shape (...) + Scaled second invariant of the deviatoric part of T_sym. + """ d = _tensor.deviatoric(T_sym) return _np.sqrt(s*_np.sum(d**2.0,axis=(-1,-2)))