added check if nGrains==1 when non-local plasticity is used

code/IO.f90

@@ -1367,6 +1367,8 @@ subroutine IO_error(error_ID,e,i,g,ext_msg)
  case (212_pInt)
    msg = 'unknown plasticity output:'
 
+ case (252_pInt)
+   msg = 'nonlocal plasticity works only for direct CPFEM, i.e. one grain per integration point'
  case (253_pInt)
    msg = 'element type not supported for nonlocal plasticity'
 

code/constitutive.f90

@@ -382,6 +382,7 @@ subroutine constitutive_init
            constitutive_sizePostResults(g,i,e) =    constitutive_dislotwin_sizePostResults(myInstance)
            
          case (constitutive_nonlocal_label)
+           if(myNgrains/=1_pInt) call IO_error(252_pInt, e,i,g)
            select case(FE_geomtype(mesh_element(2,e)))
              case (7_pInt,8_pInt,9_pInt,10_pInt)
                ! all fine