Merge branch 'rotate-Voigt' into 'development'

Rotate voigt

See merge request damask/DAMASK!463

src/lattice.f90

@@ -405,7 +405,7 @@ module lattice
 contains
 
 !--------------------------------------------------------------------------------------------------
-!> @brief module initialization
+!> @brief Module initialization
 !--------------------------------------------------------------------------------------------------
 subroutine lattice_init
 
@@ -417,7 +417,7 @@ end subroutine lattice_init
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief characteristic shear for twinning
+!> @brief Characteristic shear for twinning
 !--------------------------------------------------------------------------------------------------
 function lattice_characteristicShear_Twin(Ntwin,lattice,CoverA) result(characteristicShear)
 
@@ -491,7 +491,7 @@ end function lattice_characteristicShear_Twin
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief rotated elasticity matrices for twinning in 6x6-matrix notation
+!> @brief Rotated elasticity matrices for twinning in 6x6-matrix notation
 !--------------------------------------------------------------------------------------------------
 function lattice_C66_twin(Ntwin,C66,lattice,CoverA)
 
@@ -522,14 +522,14 @@ function lattice_C66_twin(Ntwin,C66,lattice,CoverA)
 
   do i = 1, sum(Ntwin)
     call R%fromAxisAngle([coordinateSystem(1:3,2,i),PI],P=1)                                        ! ToDo: Why always 180 deg?
-    lattice_C66_twin(1:6,1:6,i) = math_3333toVoigt66(R%rotTensor4(math_Voigt66to3333(C66)))
+    lattice_C66_twin(1:6,1:6,i) = R%rotStiffness(C66)
   enddo
 
 end function lattice_C66_twin
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief rotated elasticity matrices for transformation in 6x6-matrix notation
+!> @brief Rotated elasticity matrices for transformation in 6x6-matrix notation
 !--------------------------------------------------------------------------------------------------
 function lattice_C66_trans(Ntrans,C_parent66,lattice_target, &
                            cOverA_trans,a_bcc,a_fcc)
@@ -548,6 +548,8 @@ function lattice_C66_trans(Ntrans,C_parent66,lattice_target, &
  !--------------------------------------------------------------------------------------------------
  ! elasticity matrix of the target phase in cube orientation
   if (lattice_target == 'hP') then
+    ! https://doi.org/10.1063/1.1663858 eq. (16), eq. (18), eq. (19)
+    ! https://doi.org/10.1016/j.actamat.2016.07.032 eq. (47), eq. (48)
     if (cOverA_trans < 1.0_pReal .or. cOverA_trans > 2.0_pReal) &
       call IO_error(131,ext_msg='lattice_C66_trans: '//trim(lattice_target))
     C_bar66(1,1) = (C_parent66(1,1) + C_parent66(1,2) + 2.0_pReal*C_parent66(4,4))/2.0_pReal
@@ -581,14 +583,14 @@ function lattice_C66_trans(Ntrans,C_parent66,lattice_target, &
 
   do i = 1,sum(Ntrans)
     call R%fromMatrix(Q(1:3,1:3,i))
-    lattice_C66_trans(1:6,1:6,i) = math_3333toVoigt66(R%rotTensor4(math_Voigt66to3333(C_target_unrotated66)))
+    lattice_C66_trans(1:6,1:6,i) = R%rotStiffness(C_target_unrotated66)
   enddo
 
  end function lattice_C66_trans
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief non-Schmid projections for bcc with up to 6 coefficients
+!> @brief Non-schmid projections for bcc with up to 6 coefficients
 ! Koester et al. 2012, Acta Materialia 60 (2012) 3894–3901, eq. (17)
 ! Gröger et al. 2008, Acta Materialia 56 (2008) 5412–5425, table 1
 !--------------------------------------------------------------------------------------------------
@@ -635,7 +637,7 @@ end function lattice_nonSchmidMatrix
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief slip-slip interaction matrix
+!> @brief Slip-slip interaction matrix
 !> details only active slip systems are considered
 !--------------------------------------------------------------------------------------------------
 function lattice_interaction_SlipBySlip(Nslip,interactionValues,lattice) result(interactionMatrix)
@@ -884,7 +886,7 @@ end function lattice_interaction_SlipBySlip
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief twin-twin interaction matrix
+!> @brief Twin-twin interaction matrix
 !> details only active twin systems are considered
 !--------------------------------------------------------------------------------------------------
 function lattice_interaction_TwinByTwin(Ntwin,interactionValues,lattice) result(interactionMatrix)
@@ -983,7 +985,7 @@ end function lattice_interaction_TwinByTwin
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief trans-trans interaction matrix
+!> @brief Trans-trans interaction matrix
 !> details only active trans systems are considered
 !--------------------------------------------------------------------------------------------------
 function lattice_interaction_TransByTrans(Ntrans,interactionValues,lattice) result(interactionMatrix)
@@ -1025,7 +1027,7 @@ end function lattice_interaction_TransByTrans
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief slip-twin interaction matrix
+!> @brief Slip-twin interaction matrix
 !> details only active slip and twin systems are considered
 !--------------------------------------------------------------------------------------------------
 function lattice_interaction_SlipByTwin(Nslip,Ntwin,interactionValues,lattice) result(interactionMatrix)
@@ -1189,7 +1191,7 @@ end function lattice_interaction_SlipByTwin
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief slip-trans interaction matrix
+!> @brief Slip-trans interaction matrix
 !> details only active slip and trans systems are considered
 !--------------------------------------------------------------------------------------------------
 function lattice_interaction_SlipByTrans(Nslip,Ntrans,interactionValues,lattice) result(interactionMatrix)
@@ -1242,7 +1244,7 @@ function lattice_interaction_SlipByTrans(Nslip,Ntrans,interactionValues,lattice)
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief twin-slip interaction matrix
+!> @brief Twin-slip interaction matrix
 !> details only active twin and slip systems are considered
 !--------------------------------------------------------------------------------------------------
 function lattice_interaction_TwinBySlip(Ntwin,Nslip,interactionValues,lattice) result(interactionMatrix)
@@ -1487,7 +1489,7 @@ end function lattice_SchmidMatrix_cleavage
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief slip direction of slip systems (|| b)
+!> @brief Slip direction of slip systems (|| b)
 !--------------------------------------------------------------------------------------------------
 function lattice_slip_direction(Nslip,lattice,cOverA) result(d)
 
@@ -1505,7 +1507,7 @@ end function lattice_slip_direction
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief normal direction of slip systems (|| n)
+!> @brief Normal direction of slip systems (|| n)
 !--------------------------------------------------------------------------------------------------
 function lattice_slip_normal(Nslip,lattice,cOverA) result(n)
 
@@ -1523,7 +1525,7 @@ end function lattice_slip_normal
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief transverse direction of slip systems (|| t = b x n)
+!> @brief Transverse direction of slip systems (|| t = b x n)
 !--------------------------------------------------------------------------------------------------
 function lattice_slip_transverse(Nslip,lattice,cOverA) result(t)
 
@@ -1541,7 +1543,7 @@ end function lattice_slip_transverse
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief labels of slip systems
+!> @brief Labels of slip systems
 !> details only active slip systems are considered
 !--------------------------------------------------------------------------------------------------
 function lattice_labels_slip(Nslip,lattice) result(labels)
@@ -1582,7 +1584,7 @@ end function lattice_labels_slip
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief return 3x3 tensor with symmetry according to given Bravais lattice
+!> @brief Return 3x3 tensor with symmetry according to given Bravais lattice
 !--------------------------------------------------------------------------------------------------
 pure function lattice_symmetrize_33(T,lattice) result(T_sym)
 
@@ -1609,7 +1611,7 @@ end function lattice_symmetrize_33
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief return stiffness matrix in 6x6 notation with symmetry according to given Bravais lattice
+!> @brief Return stiffness matrix in 6x6 notation with symmetry according to given Bravais lattice
 !> @details J. A. Rayne and B. S. Chandrasekhar Phys. Rev. 120, 1658 Erratum Phys. Rev. 122, 1962
 !--------------------------------------------------------------------------------------------------
 pure function lattice_symmetrize_C66(C66,lattice) result(C66_sym)
@@ -1655,7 +1657,7 @@ end function lattice_symmetrize_C66
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief labels of twin systems
+!> @brief Labels for twin systems
 !> details only active twin systems are considered
 !--------------------------------------------------------------------------------------------------
 function lattice_labels_twin(Ntwin,lattice) result(labels)
@@ -1693,7 +1695,7 @@ end function lattice_labels_twin
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief projection of the transverse direction onto the slip plane
+!> @brief Projection of the transverse direction onto the slip plane
 !> @details: This projection is used to calculate forest hardening for edge dislocations
 !--------------------------------------------------------------------------------------------------
 function slipProjection_transverse(Nslip,lattice,cOverA) result(projection)
@@ -1717,7 +1719,7 @@ end function slipProjection_transverse
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief projection of the slip direction onto the slip plane
+!> @brief Projection of the slip direction onto the slip plane
 !> @details: This projection is used to calculate forest hardening for screw dislocations
 !--------------------------------------------------------------------------------------------------
 function slipProjection_direction(Nslip,lattice,cOverA) result(projection)
@@ -1783,7 +1785,7 @@ end function coordinateSystem_slip
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief populate reduced interaction matrix
+!> @brief Populate reduced interaction matrix
 !--------------------------------------------------------------------------------------------------
 function buildInteraction(reacting_used,acting_used,reacting_max,acting_max,values,matrix)
 
@@ -1826,7 +1828,7 @@ end function buildInteraction
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief build a local coordinate system on slip, twin, trans, cleavage systems
+!> @brief Build a local coordinate system on slip, twin, trans, cleavage systems
 !> @details Order: Direction, plane (normal), and common perpendicular
 !--------------------------------------------------------------------------------------------------
 function buildCoordinateSystem(active,potential,system,lattice,cOverA)
@@ -1893,7 +1895,7 @@ end function buildCoordinateSystem
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief helper function to define transformation systems
+!> @brief Helper function to define transformation systems
 ! Needed to calculate Schmid matrix and rotated stiffness matrices.
 ! @details: set c/a   = 0.0 for fcc -> bcc transformation
 !           set a_Xcc = 0.0 for fcc -> hex transformation
@@ -2077,7 +2079,7 @@ end function getlabels
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief equivalent Poisson's ratio (ν)
+!> @brief Equivalent Poisson's ratio (ν)
 !> @details https://doi.org/10.1143/JPSJ.20.635
 !--------------------------------------------------------------------------------------------------
 function lattice_equivalent_nu(C,assumption) result(nu)
@@ -2110,7 +2112,7 @@ end function lattice_equivalent_nu
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief equivalent shear modulus (μ)
+!> @brief Equivalent shear modulus (μ)
 !> @details https://doi.org/10.1143/JPSJ.20.635
 !--------------------------------------------------------------------------------------------------
 function lattice_equivalent_mu(C,assumption) result(mu)
@@ -2139,7 +2141,7 @@ end function lattice_equivalent_mu
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief check correctness of some lattice functions
+!> @brief Check correctness of some lattice functions.
 !--------------------------------------------------------------------------------------------------
 subroutine selfTest
 

src/math.f90

@@ -806,7 +806,7 @@ pure function math_sym3333to66(m3333,weighted)
     w = merge(NRMMANDEL,1.0_pReal,weighted)
   else
     w = NRMMANDEL
-  endif
+  end if
 
 #ifndef __INTEL_COMPILER
   do concurrent(i=1:6, j=1:6)
@@ -841,20 +841,83 @@ pure function math_66toSym3333(m66,weighted)
     w = merge(INVNRMMANDEL,1.0_pReal,weighted)
   else
     w = INVNRMMANDEL
-  endif
+  end if
 
   do i=1,6; do j=1,6
     math_66toSym3333(MAPNYE(1,i),MAPNYE(2,i),MAPNYE(1,j),MAPNYE(2,j)) = w(i)*w(j)*m66(i,j)
     math_66toSym3333(MAPNYE(2,i),MAPNYE(1,i),MAPNYE(1,j),MAPNYE(2,j)) = w(i)*w(j)*m66(i,j)
     math_66toSym3333(MAPNYE(1,i),MAPNYE(2,i),MAPNYE(2,j),MAPNYE(1,j)) = w(i)*w(j)*m66(i,j)
     math_66toSym3333(MAPNYE(2,i),MAPNYE(1,i),MAPNYE(2,j),MAPNYE(1,j)) = w(i)*w(j)*m66(i,j)
-  enddo; enddo
+  end do; end do
 
 end function math_66toSym3333
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief convert 6x6 Voigt matrix into symmetric 3x3x3x3 matrix
+!> @brief Convert 6 Voigt stress vector into symmetric 3x3 tensor.
+!--------------------------------------------------------------------------------------------------
+pure function math_Voigt6to33_stress(sigma_tilde) result(sigma)
+
+  real(pReal), dimension(3,3) :: sigma
+  real(pReal), dimension(6), intent(in) :: sigma_tilde
+
+
+  sigma = reshape([sigma_tilde(1), sigma_tilde(6), sigma_tilde(5), &
+                   sigma_tilde(6), sigma_tilde(2), sigma_tilde(4), &
+                   sigma_tilde(5), sigma_tilde(4), sigma_tilde(3)],[3,3])
+
+end function math_Voigt6to33_stress
+
+
+!--------------------------------------------------------------------------------------------------
+!> @brief Convert 6 Voigt strain vector into symmetric 3x3 tensor.
+!--------------------------------------------------------------------------------------------------
+pure function math_Voigt6to33_strain(epsilon_tilde) result(epsilon)
+
+  real(pReal), dimension(3,3) :: epsilon
+  real(pReal), dimension(6), intent(in) :: epsilon_tilde
+
+
+  epsilon = reshape([          epsilon_tilde(1), 0.5_pReal*epsilon_tilde(6), 0.5_pReal*epsilon_tilde(5), &
+                     0.5_pReal*epsilon_tilde(6),           epsilon_tilde(2), 0.5_pReal*epsilon_tilde(4), &
+                     0.5_pReal*epsilon_tilde(5), 0.5_pReal*epsilon_tilde(4),           epsilon_tilde(3)],[3,3])
+
+end function math_Voigt6to33_strain
+
+
+!--------------------------------------------------------------------------------------------------
+!> @brief Convert 3x3 tensor into 6 Voigt stress vector.
+!--------------------------------------------------------------------------------------------------
+pure function math_33toVoigt6_stress(sigma) result(sigma_tilde)
+
+  real(pReal), dimension(6) :: sigma_tilde
+  real(pReal), dimension(3,3), intent(in) :: sigma
+
+
+  sigma_tilde = [sigma(1,1), sigma(2,2), sigma(3,3), &
+                 sigma(3,2), sigma(3,1), sigma(1,2)] 
+
+end function math_33toVoigt6_stress
+
+
+!--------------------------------------------------------------------------------------------------
+!> @brief Convert 3x3 tensor into 6 Voigt strain vector.
+!--------------------------------------------------------------------------------------------------
+pure function math_33toVoigt6_strain(epsilon) result(epsilon_tilde)
+
+  real(pReal), dimension(6) :: epsilon_tilde
+  real(pReal), dimension(3,3), intent(in) :: epsilon
+
+
+  epsilon_tilde = [          epsilon(1,1),           epsilon(2,2),           epsilon(3,3), &
+                   2.0_pReal*epsilon(3,2), 2.0_pReal*epsilon(3,1), 2.0_pReal*epsilon(1,2)] 
+
+end function math_33toVoigt6_strain
+
+
+
+!--------------------------------------------------------------------------------------------------
+!> @brief Convert 6x6 Voigt matrix into symmetric 3x3x3x3 matrix.
 !--------------------------------------------------------------------------------------------------
 pure function math_Voigt66to3333(m66)
 
@@ -864,18 +927,18 @@ pure function math_Voigt66to3333(m66)
   integer :: i,j
 
 
-  do i=1,6; do j=1, 6
+  do i=1,6; do j=1,6
     math_Voigt66to3333(MAPVOIGT(1,i),MAPVOIGT(2,i),MAPVOIGT(1,j),MAPVOIGT(2,j)) = m66(i,j)
     math_Voigt66to3333(MAPVOIGT(2,i),MAPVOIGT(1,i),MAPVOIGT(1,j),MAPVOIGT(2,j)) = m66(i,j)
     math_Voigt66to3333(MAPVOIGT(1,i),MAPVOIGT(2,i),MAPVOIGT(2,j),MAPVOIGT(1,j)) = m66(i,j)
     math_Voigt66to3333(MAPVOIGT(2,i),MAPVOIGT(1,i),MAPVOIGT(2,j),MAPVOIGT(1,j)) = m66(i,j)
-  enddo; enddo
+  end do; end do
 
 end function math_Voigt66to3333
 
 
 !--------------------------------------------------------------------------------------------------
-!> @brief convert symmetric 3x3x3x3 matrix into 6x6 Voigt matrix
+!> @brief Convert symmetric 3x3x3x3 matrix into 6x6 Voigt matrix.
 !--------------------------------------------------------------------------------------------------
 pure function math_3333toVoigt66(m3333)
 

src/phase_mechanical_elastic.f90

@@ -193,15 +193,17 @@ module subroutine phase_hooke_SandItsTangents(S, dS_dFe, dS_dFi, &
     dS_dFi                                                                                          !< derivative of 2nd P-K stress with respect to intermediate deformation gradient
 
   real(pReal), dimension(3,3) :: E
+  real(pReal), dimension(6,6) :: C66
   real(pReal), dimension(3,3,3,3) :: C
   integer :: &
     i, j
 
 
-  C = math_Voigt66to3333(phase_damage_C66(phase_homogenizedC66(ph,en),ph,en))
+  C66 = phase_damage_C66(phase_homogenizedC66(ph,en),ph,en)
+  C = math_Voigt66to3333(C66)
 
   E = 0.5_pReal*(matmul(transpose(Fe),Fe)-math_I3)                                                  !< Green-Lagrange strain in unloaded configuration
-  S = math_mul3333xx33(C,matmul(matmul(transpose(Fi),E),Fi))                                        !< 2PK stress in lattice configuration in work conjugate with GL strain pulled back to lattice configuration
+  S = math_Voigt6to33_stress(matmul(C66,math_33toVoigt6_strain(matmul(matmul(transpose(Fi),E),Fi))))!< 2PK stress in lattice configuration in work conjugate with GL strain pulled back to lattice configuration
 
   do i =1,3; do j=1,3
     dS_dFe(i,j,1:3,1:3) = matmul(Fe,matmul(matmul(Fi,C(i,j,1:3,1:3)),transpose(Fi)))                !< dS_ij/dFe_kl = C_ijmn * Fi_lm * Fi_on * Fe_ko

src/rotations.f90

@@ -75,6 +75,7 @@ module rotations
       procedure, public  :: rotVector
       procedure, public  :: rotTensor2
       procedure, public  :: rotTensor4
+      procedure, public  :: rotStiffness
       procedure, public  :: misorientation
       procedure, public  :: standardize
   end type rotation
@@ -339,8 +340,7 @@ end function rotTensor2
 
 
 !---------------------------------------------------------------------------------------------------
-!> @author Martin Diehl, Max-Planck-Institut für Eisenforschung GmbH
+!> @brief Rotate a rank-4 tensor passively (default) or actively.
-!> @brief rotate a rank-4 tensor passively (default) or actively
 !> @details: rotation is based on rotation matrix
 !! ToDo: Need to check active/passive !!!
 !---------------------------------------------------------------------------------------------------
@@ -354,6 +354,7 @@ pure function rotTensor4(self,T,active) result(tRot)
   real(pReal), dimension(3,3) :: R
   integer :: i,j,k,l,m,n,o,p
 
+
   if (present(active)) then
     R = merge(transpose(self%asMatrix()),self%asMatrix(),active)
   else
@@ -371,7 +372,47 @@ end function rotTensor4
 
 
 !---------------------------------------------------------------------------------------------------
-!> @brief misorientation
+!> @brief Rotate a rank-4 tensor in Voigt 6x6 notation passively (default) or actively.
+!> @details: https://scicomp.stackexchange.com/questions/35600
+!! ToDo: Need to check active/passive !!!
+!---------------------------------------------------------------------------------------------------
+pure function rotStiffness(self,C,active) result(cRot)
+
+  real(pReal),                 dimension(6,6) :: cRot
+  class(rotation), intent(in)                 :: self
+  real(pReal),     intent(in), dimension(6,6) :: C
+  logical,         intent(in), optional       :: active
+
+  real(pReal), dimension(3,3) :: R
+  real(pReal), dimension(6,6) :: M
+
+
+  if (present(active)) then
+    R = merge(transpose(self%asMatrix()),self%asMatrix(),active)
+  else
+    R = self%asMatrix()
+  endif
+
+  M = reshape([R(1,1)**2.0_pReal,           R(2,1)**2.0_pReal,           R(3,1)**2.0_pReal, &
+               R(2,1)*R(3,1),               R(1,1)*R(3,1),               R(1,1)*R(2,1), &
+               R(1,2)**2.0_pReal,           R(2,2)**2.0_pReal,           R(3,2)**2.0_pReal, &
+               R(2,2)*R(3,2),               R(1,2)*R(3,2),               R(1,2)*R(2,2), &
+               R(1,3)**2.0_pReal,           R(2,3)**2.0_pReal,           R(3,3)**2.0_pReal, &
+               R(2,3)*R(3,3),               R(1,3)*R(3,3),               R(1,3)*R(2,3), &
+               2.0_pReal*R(1,2)*R(1,3),     2.0_pReal*R(2,2)*R(2,3),     2.0_pReal*R(3,2)*R(3,3), &
+               R(2,2)*R(3,3)+R(2,3)*R(3,2), R(1,2)*R(3,3)+R(1,3)*R(3,2), R(1,2)*R(2,3)+R(1,3)*R(2,2), &
+               2.0_pReal*R(1,3)*R(1,1),     2.0_pReal*R(2,3)*R(2,1),     2.0_pReal*R(3,3)*R(3,1), &
+               R(2,3)*R(3,1)+R(2,1)*R(3,3), R(1,3)*R(3,1)+R(1,1)*R(3,3), R(1,3)*R(2,1)+R(1,1)*R(2,3), &
+               2.0_pReal*R(1,1)*R(1,2),     2.0_pReal*R(2,1)*R(2,2),     2.0_pReal*R(3,1)*R(3,2), &
+               R(2,1)*R(3,2)+R(2,2)*R(3,1), R(1,1)*R(3,2)+R(1,2)*R(3,1), R(1,1)*R(2,2)+R(1,2)*R(2,1)],[6,6])
+
+  cRot = matmul(M,matmul(C,transpose(M)))
+
+end function rotStiffness
+
+
+!---------------------------------------------------------------------------------------------------
+!> @brief Misorientation.
 !---------------------------------------------------------------------------------------------------
 pure elemental function misorientation(self,other)
 
@@ -386,7 +427,7 @@ end function misorientation
 
 !---------------------------------------------------------------------------------------------------
 !> @author Marc De Graef, Carnegie Mellon University
-!> @brief convert unit quaternion to rotation matrix
+!> @brief Convert unit quaternion to rotation matrix.
 !---------------------------------------------------------------------------------------------------
 pure function qu2om(qu) result(om)
 
@@ -395,8 +436,8 @@ pure function qu2om(qu) result(om)
 
   real(pReal)                             :: qq
 
-  qq = qu(1)**2-sum(qu(2:4)**2)
 
+  qq = qu(1)**2-sum(qu(2:4)**2)
 
   om(1,1) = qq+2.0_pReal*qu(2)**2
   om(2,2) = qq+2.0_pReal*qu(3)**2
@@ -416,7 +457,7 @@ end function qu2om
 
 !---------------------------------------------------------------------------------------------------
 !> @author Marc De Graef, Carnegie Mellon University
-!> @brief convert unit quaternion to Euler angles
+!> @brief Convert unit quaternion to Euler angles.
 !---------------------------------------------------------------------------------------------------
 pure function qu2eu(qu) result(eu)
 
@@ -425,6 +466,7 @@ pure function qu2eu(qu) result(eu)
 
   real(pReal)                           :: q12, q03, chi
 
+
   q03 = qu(1)**2+qu(4)**2
   q12 = qu(2)**2+qu(3)**2
   chi = sqrt(q03*q12)
@@ -1379,6 +1421,7 @@ subroutine selfTest()
   real(pReal), dimension(3)       :: x, eu, ho, v3
   real(pReal), dimension(3,3)     :: om, t33
   real(pReal), dimension(3,3,3,3) :: t3333
+  real(pReal), dimension(6,6)     :: C
   real    :: A,B
   integer :: i
 
@@ -1412,6 +1455,7 @@ subroutine selfTest()
       if(qu(1)<0.0_pReal) qu = qu * (-1.0_pReal)
     endif
 
+
     if(.not. quaternion_equal(om2qu(qu2om(qu)),qu)) error stop 'om2qu/qu2om'
     if(.not. quaternion_equal(eu2qu(qu2eu(qu)),qu)) error stop 'eu2qu/qu2eu'
     if(.not. quaternion_equal(ax2qu(qu2ax(qu)),qu)) error stop 'ax2qu/qu2ax'
@@ -1447,20 +1491,25 @@ subroutine selfTest()
     call R%fromMatrix(om)
 
     call random_number(v3)
-    if(all(dNeq(R%rotVector(R%rotVector(v3),active=.true.),v3,1.0e-12_pReal))) &
+    if (any(dNeq(R%rotVector(R%rotVector(v3),active=.true.),v3,1.0e-12_pReal))) &
       error stop 'rotVector'
 
     call random_number(t33)
-    if(all(dNeq(R%rotTensor2(R%rotTensor2(t33),active=.true.),t33,1.0e-12_pReal))) &
+    if (any(dNeq(R%rotTensor2(R%rotTensor2(t33),active=.true.),t33,1.0e-12_pReal))) &
       error stop 'rotTensor2'
 
     call random_number(t3333)
-    if(all(dNeq(R%rotTensor4(R%rotTensor4(t3333),active=.true.),t3333,1.0e-12_pReal))) &
+    if (any(dNeq(R%rotTensor4(R%rotTensor4(t3333),active=.true.),t3333,1.0e-12_pReal))) &
       error stop 'rotTensor4'
 
+    call random_number(C)
+    C = C+transpose(C)
+    if (any(dNeq(R%rotStiffness(C),math_3333toVoigt66(R%rotate(math_Voigt66to3333(C))),1.0e-12_pReal))) &
+      error stop 'rotStiffness'
+
     call R%fromQuaternion(qu * (1.0_pReal + merge(+5.e-9_pReal,-5.e-9_pReal, mod(i,2) == 0)))       ! allow reasonable tolerance for ASCII/YAML
 
-  enddo
+  end do
 
   contains