Proper handling of MPC complings between solid models

CHANGELOG.md

@@ -8,6 +8,17 @@
 
 # FEDEM solvers Changelog
 
+## [fedem-8.1.5.2] (2026-03-22)
+
+### :bug: Fixed
+
+- Issue https://github.com/openfedem/fedem-solvers/issues/49 :
+  Component mode calculation does not work for FE parts
+  containing explicit MPC-couplings between solid elements.
+- Issue https://github.com/openfedem/fedem-solvers/issues/46 :
+  The linear equation solver does not always abort the simulation when
+  a singularity is detected, and may instead produce invalid results.
+
 ## [fedem-8.1.5] (2026-03-15)
 
 ### :rocket: Added
@@ -24,8 +35,9 @@
 
 ### :rocket: Added
 
-The two points defining the state-dependent direction of a point load may
-now be specified by triads in addition to points on a superelement.
+- Issue https://github.com/openfedem/fedem-gui/issues/128 :
+  The two points defining the state-dependent direction of a point load
+  may now be specified by triads in addition to points on a superelement.
 
 ## [fedem-8.1.3] (2026-01-20)
 
@@ -187,3 +199,6 @@ Only the version tags are updated to align with the FEDEM GUI.
 [fedem-8.0.9]: https://github.com/openfedem/fedem-solvers/compare/fedem-8.0.8...fedem-8.0.9
 [fedem-8.1.0]: https://github.com/openfedem/fedem-solvers/compare/fedem-8.0.9...fedem-8.1.0
 [fmu-8.1.2]: https://github.com/openfedem/fedem-solvers/compare/fedem-8.1.1...fmu-8.1.2
+[fedem-8.1.3]: https://github.com/openfedem/fedem-solvers/compare/fmu-8.1.2...fedem-8.1.3
+[fedem-8.1.4]: https://github.com/openfedem/fedem-solvers/compare/fedem-8.1.3...fedem-8.1.4
+[fedem-8.1.5]: https://github.com/openfedem/fedem-solvers/compare/fedem-8.1.4...fedem-8.1.5

src/vpmReducer/rigidModule.f90

@@ -109,7 +109,7 @@ subroutine MultiPointConstraints (MINEX,MADOF,MPAM,MPMNPC,MMNPC,TXC,TYC,TZC, &
     !! Local variables
     character(len=128)    :: errMsg
     integer               :: i, j, k, l, n, iel, xel, iam, iceq, ipcur, iwarn
-    integer               :: depDof, refC, ignoredC(3), indC(6), nenod, nW
+    integer               :: depDof, refC, ignoredC(3), indC(7), nenod, nW
     logical               :: refDofs(6)
     real(dp)              :: sumW, epsX, X0(3), tolX(3)
     integer , allocatable :: mDofs(:)
@@ -196,9 +196,19 @@ subroutine MultiPointConstraints (MINEX,MADOF,MPAM,MPMNPC,MMNPC,TXC,TYC,TZC, &
           !! No properties defined - use default settings
           refC = 123456
           indC(1:3) = -1
-          indC(4:6) = 0
+          indC(4:7) = 0
        else if (ierr < 0) then
           goto 900
+       else if (refC < 0) then
+          !! Explicit constraints
+          ierr = ierr + 1 ! Index to past the end of the weight array
+          indC(7) = 0
+          do i = 7, 2, -1
+             if (indC(i-1) > 0) then
+                if (indC(i) == 0) indC(i) = ierr
+                ierr = indC(i-1)
+             end if
+          end do
        end if
 
        if (ffa_cmdlinearg_isTrue('useOldWAVGM')) then !TODO: Remove this later
@@ -238,11 +248,12 @@ subroutine MultiPointConstraints (MINEX,MADOF,MPAM,MPMNPC,MMNPC,TXC,TYC,TZC, &
 
           if (refC >= 0) then
              !! Compute constraint coefficients from the WAVGM definitions
-             call wavgmConstrEqn (xel,i,nenod,indC,txc,tyc,tzc, &
+             call wavgmConstrEqn (xel,i,nenod,indC(1:6),txc,tyc,tzc, &
                   &               mmnpc(mpmnpc(iel):mpmnpc(iel+1)-1), &
                   &               epsX,tolX,deltaX,work,weight,omega,ipsw,lpu)
-          else ! Explicit constraints (assuming 6 DOFs per independent node)
-             call explConstrEqn (6*nenod,indC(i),weight,omega)
+          else ! Explicit constraints
+             nw = (indC(i+1) - indC(i)) / nenod
+             call explConstrEqn (nenod,indC(i),nw,weight,omega)
           end if
 
           !! Find global DOF numbers for the independent DOFs
@@ -337,14 +348,22 @@ subroutine MultiPointConstraints (MINEX,MADOF,MPAM,MPMNPC,MMNPC,TXC,TYC,TZC, &
   !> @details Assuming here that all independent nodes have six DOFs.
   !> See also FFlSesamReader::readLinearDependencies(), where the
   !> weight matrix is populated from the SESAM BLDEP records.
-  subroutine explConstrEqn (nedof,indC,weight,omega)
-    integer , intent(in)  :: nedof, indC
+  subroutine explConstrEqn (nenod,i1,nndof,weight,omega)
+    integer , intent(in)  :: nenod, i1, nndof
     real(dp), intent(in)  :: weight(:)
-    real(dp), intent(out) :: omega(:)
-    if (indC > 0 .and. indC+nedof-1 <= size(weight)) then
-       call DCOPY (nedof,weight(indC),1,omega(1),1)
-    else ! Assume equal weight on all DOFs
-       call DCOPY (nedof,1.0_dp,0,omega(1),1)
+    real(dp), intent(out) :: omega(6,nenod)
+    if (i1 < 1) then
+       !! Assume equal weight on all DOFs
+       call DCOPY (6*nenod,1.0_dp,0,omega(1,1),1)
+    else if (nndof >= 6) then
+       call DCOPY (6*nenod,weight(i1),1,omega(1,1),1)
+    else
+       k = i1
+       do j = 1, nenod
+          omega(1:nndof  ,j) = weight(k:k+nndof-1)
+          omega(1+nndof:6,j) = 0.0_dp
+          k = k + nndof
+       end do
     end if
   end subroutine explConstrEqn
 

src/vpmReducer/saveReducerModule.f90

@@ -5,6 +5,17 @@
 !! This file is part of FEDEM - https://openfedem.org
 !!==============================================================================
 
+!> @file saveReducerModule.f90
+!>
+!> @brief Save of FE model reduction data to result database files.
+
+!!==============================================================================
+!> @brief Module with subroutines for saving of FE model reduction results.
+!>
+!> @details This module contains a collection of subroutines for writing results
+!> data from the FE model reduction process or direct linear solve
+!> to the results database.
+
 module saveReducerModule
 
   implicit none
@@ -19,14 +30,23 @@ module saveReducerModule
 
 contains
 
-  subroutine writeModes (chname,sam,partId,modeType,nMode,ev,sv,ierr)
+  !!============================================================================
+  !> @brief Administers writing of results database for fedem_reducer.
+  !>
+  !> @param[in] chname Name of frs-file receiving the results data
+  !> @param[in] sam Data for managing system matrix assembly
+  !> @param[in] partId Base ID of the FE part
+  !> @param[in] modeType Name of eigenmode item group
+  !> @param[in] nMode Number of eigenmodes
+  !> @param[in] ev Eigenvalues
+  !> @param[in] sv Eigenvectors
+  !> @param[out] ierr Error flag
+  !>
+  !> @author Knut Morten Okstad
+  !>
+  !> @date 4 Oct 2002
 
-    !!==========================================================================
-    !! Administer writing of results database for fedem_reducer.
-    !!
-    !! Programmer : Knut Morten Okstad
-    !! date/rev   : 4 Oct 2002/1.0
-    !!==========================================================================
+  subroutine writeModes (chname,sam,partId,modeType,nMode,ev,sv,ierr)
 
     use KindModule            , only : dp, i8, lfnam_p
     use RDBModule             , only : RDBType, idatd, openRDBfile, closeRDBfile
@@ -102,14 +122,23 @@ subroutine writeModes (chname,sam,partId,modeType,nMode,ev,sv,ierr)
   end subroutine writeModes
 
 
-  subroutine writeDeformation (chname,sam,partId,nlc,mlc,sv,lpu,ierr)
+  !!============================================================================
+  !> @brief Administers writing of results database for fedem_partsol.
+  !>
+  !> @param[in] chname Name of frs-file receiving the results data
+  !> @param[in] sam Data for managing system matrix assembly
+  !> @param[in] partId Base ID of the FE part
+  !> @param[in] nlc Number of load cases
+  !> @param[in] mlc Load case identifiers
+  !> @param[in] sv Displacement vector in equation order
+  !> @param[in] lpu File unit number for res-file output
+  !> @param[out] ierr Error flag
+  !>
+  !> @author Knut Morten Okstad
+  !>
+  !> @date 19 Mar 2018
 
-    !!==========================================================================
-    !! Administer writing of results database for fedem_reducer.
-    !!
-    !! Programmer : Knut Morten Okstad
-    !! date/rev   : 19 Mar 2018/1.0
-    !!==========================================================================
+  subroutine writeDeformation (chname,sam,partId,nlc,mlc,sv,lpu,ierr)
 
     use KindModule            , only : dp, lfnam_p
     use SamModule             , only : SamType
@@ -178,14 +207,20 @@ subroutine writeDeformation (chname,sam,partId,nlc,mlc,sv,lpu,ierr)
   end subroutine writeDeformation
 
 
-  subroutine writeModesHeader (rdb,nMode,nbit)
+  !!============================================================================
+  !> @brief Writes modal result definitions to the temporary header files.
+  !>
+  !> @param rdb Results database file for modes output
+  !> @param[in] nMode Number of mode shapes
+  !> @param[in] nbit Number of bits per real word
+  !>
+  !> @author Knut Morten Okstad
+  !>
+  !> @callergraph
+  !>
+  !> @date 4 Oct 2002
 
-    !!==========================================================================
-    !! Write modal result definitions to the temporary header files.
-    !!
-    !! Programmer : Knut Morten Okstad
-    !! date/rev   : 4 Oct 2002/1.0
-    !!==========================================================================
+  subroutine writeModesHeader (rdb,nMode,nbit)
 
     use RDBModule, only : rDBType, idatd, ivard