diff --git a/data/config/config_iteration_dump.msp b/data/config/config_iteration_dump.msp
index 7c682cc..01a350a 100644
--- a/data/config/config_iteration_dump.msp
+++ b/data/config/config_iteration_dump.msp
@@ -23,7 +23,7 @@ write_paraview_generic:
   binary: false
   write_ghost: false
   write_box: true
-  fields: ["vx","vy","vz","id","orient"]
+  fields: ["type","vx","vy","vz","id","orient"]
 #  fields: ["vx","vy","vz","id","radius"]
 
 dump_data_paraview:
diff --git a/example/polyhedra/rotating_drum/CMakeLists.txt b/example/polyhedra/rotating_drum/CMakeLists.txt
index 79f786d..ff598a2 100644
--- a/example/polyhedra/rotating_drum/CMakeLists.txt
+++ b/example/polyhedra/rotating_drum/CMakeLists.txt
@@ -3,6 +3,15 @@ set(ExampleName "OctahedraRotatingDrum")
 set(FileName "rotating-drum.msp")
 
 file(COPY ${CMAKE_CURRENT_SOURCE_DIR}/shapes.shp DESTINATION ${CMAKE_CURRENT_BINARY_DIR})
+file(COPY ${CMAKE_CURRENT_SOURCE_DIR}/alpha3.shp DESTINATION ${CMAKE_CURRENT_BINARY_DIR})
+file(COPY ${CMAKE_CURRENT_SOURCE_DIR}/octahedron.shp DESTINATION ${CMAKE_CURRENT_BINARY_DIR})
+
+add_test(Example_ExaDEM_${ExampleName} ${CMAKE_BINARY_DIR}/exaDEM ${CMAKE_CURRENT_SOURCE_DIR}/${FileName} --omp_num_threads 1)
+add_test(Example_ExaDEM_${ExampleName}_omp ${CMAKE_BINARY_DIR}/exaDEM ${CMAKE_CURRENT_SOURCE_DIR}/${FileName} --omp_num_threads 2)
+add_test(Example_ExaDEM_${ExampleName}_mpi mpirun -n 2 ${CMAKE_BINARY_DIR}/exaDEM ${CMAKE_CURRENT_SOURCE_DIR}/${FileName} --omp_num_threads 1)
+
+set(ExampleName "OctahedraHexapodsRotatingDrum")
+set(FileName "rotating-drum-mixte-mini.msp")
 
 add_test(Example_ExaDEM_${ExampleName} ${CMAKE_BINARY_DIR}/exaDEM ${CMAKE_CURRENT_SOURCE_DIR}/${FileName} --omp_num_threads 1)
 add_test(Example_ExaDEM_${ExampleName}_omp ${CMAKE_BINARY_DIR}/exaDEM ${CMAKE_CURRENT_SOURCE_DIR}/${FileName} --omp_num_threads 2)
diff --git a/example/polyhedra/rotating_drum/alpha3.shp b/example/polyhedra/rotating_drum/alpha3.shp
new file mode 100644
index 0000000..54f1e1f
--- /dev/null
+++ b/example/polyhedra/rotating_drum/alpha3.shp
@@ -0,0 +1,25 @@
+
+<
+name alpha3
+radius 0.237770037899799
+preCompDone y
+nv 6
+0.475540075799599 0 0
+-0.475540075799599 0 0
+0 0.475540075799599 0
+0 -0.475540075799599 0
+0 0 0.475540075799599
+0 0 -0.475540075799599
+ne 3
+0 1
+2 3
+4 5
+nf 0
+obb.extent 0.713310113699398 0.713310113699398 0.713310113699398
+obb.e1 1 0 0
+obb.e2 0 1 0
+obb.e3 0 0 1
+obb.center 0 0 0
+volume 0.523598775598299
+I/m 0.13266 0.13266 0.13266
+>
diff --git a/example/polyhedra/rotating_drum/octahedron.shp b/example/polyhedra/rotating_drum/octahedron.shp
new file mode 100644
index 0000000..82acda4
--- /dev/null
+++ b/example/polyhedra/rotating_drum/octahedron.shp
@@ -0,0 +1,44 @@
+
+<
+name Octahedron
+radius 0.1
+preCompDone y
+nv 6
+0.2310789034541148 -0.2310789034541148 0.0
+0.2310789034541148 0.2310789034541148 0.0
+0.0 0.0 0.32679491924311227
+-0.2310789034541148 -0.2310789034541148 0.0
+-0.2310789034541148 0.2310789034541148 0.0
+0.0 0.0 -0.32679491924311227
+ne 12
+0 1
+2 1
+2 0
+0 3
+2 3
+3 4
+4 2
+4 1
+5 0
+5 1
+5 4
+5 3
+nf 8
+3 0 1 2 
+3 2 3 4 
+3 1 2 4 
+3 0 2 3 
+3 0 5 1 
+3 0 5 3 
+3 3 5 4 
+3 4 5 1 
+obb.extent 0.33107890345411484 0.33107890345411484 0.4267949192431123
+obb.e1 1.0 0.0 0.0
+obb.e2 0.0 1.0 0.0
+obb.e3 0.0 0.0 1.0
+obb.center 0.0 0.0 0.0
+position 0.0 0.0 0.0
+orientation 1.0 0.0 0.0 0.0
+volume 0.16666666666666666
+I/m 0.04999999999999999 0.04999999999999999 0.04999999999999999
+>
diff --git a/example/polyhedra/rotating_drum/rotating-drum-mixte-mini.msp b/example/polyhedra/rotating_drum/rotating-drum-mixte-mini.msp
new file mode 100644
index 0000000..89817c5
--- /dev/null
+++ b/example/polyhedra/rotating_drum/rotating-drum-mixte-mini.msp
@@ -0,0 +1,60 @@
+grid_flavor: grid_flavor_dem
+
+includes:
+  - config_polyhedra.msp
+
+input_data:
+  - lattice:
+      structure: BCC
+      types: [ 0 , 1 ]
+      size: [ 1.5 , 1.5 , 1.5 ]
+      repeats: [ 5 , 5 , 5 ]
+      enlarge_bounds: 0.0 m
+  - read_shape_file:
+     filename: alpha3.shp
+  - read_shape_file:
+     filename: octahedron.shp
+  - polyhedra_define_radius
+  - polyhedra_set_density
+  - set_rand_velocity:
+     var: 0.1
+     mean: [0.0,0.0,0.0]
+  - set_rand_vrot_arot
+  - set_quaternion
+  - polyhedra_update_inertia
+
+
+input_data:
+  - reader1
+
+setup_drivers:
+  - add_cylinder:
+     id: 0
+     center: [7.5, 7.5, 7.5]
+     axis: [1, 0, 1]
+     radius: 13
+     angular_velocity: [0,0.2,0]
+
+
+compute_force:
+  - gravity_force
+  - compute_hooke_interaction:
+     config: { rcut: 0.0 m , dncut: 0.0 m, kn: 10000, kt: 8000, kr: 0.0, fc: 0.0, mu: 0.1, damp_rate: 0.999} 
+     config_driver: { rcut: 0.0 m , dncut: 0.0 m, kn: 10000, kt: 8000, kr: 0.0, fc: 0.0, mu: 0.5, damp_rate: 0.999} 
+
+domain:
+  cell_size: 2 m
+  periodic: [false,true,false]
+
+write_vtklegacy:
+  ascii: true
+  ghost: false
+
+global:
+  simulation_dump_frequency: -1
+  simulation_end_iteration: 10000
+  simulation_log_frequency: 1000
+  simulation_paraview_frequency: -1
+  dt: 0.00005 s 
+  rcut_inc: 0.1 m
+  enable_stl_mesh: true
diff --git a/example/polyhedra/rotating_drum/rotating-drum-mixte.msp b/example/polyhedra/rotating_drum/rotating-drum-mixte.msp
new file mode 100644
index 0000000..a7907f7
--- /dev/null
+++ b/example/polyhedra/rotating_drum/rotating-drum-mixte.msp
@@ -0,0 +1,60 @@
+grid_flavor: grid_flavor_dem
+
+includes:
+  - config_polyhedra.msp
+
+input_data:
+  - lattice:
+      structure: BCC
+      types: [ 0 , 1 ]
+      size: [ 1.5 , 1.5 , 1.5 ]
+      repeats: [ 30 , 30 , 30 ]
+      enlarge_bounds: 0.0 m
+  - read_shape_file:
+     filename: alpha3.shp
+  - read_shape_file:
+     filename: octahedron.shp
+  - polyhedra_define_radius
+  - polyhedra_set_density
+  - set_rand_velocity:
+     var: 0.1
+     mean: [0.0,0.0,0.0]
+  - set_rand_vrot_arot
+  - set_quaternion
+  - polyhedra_update_inertia
+
+
+input_data:
+  - reader1
+
+setup_drivers:
+  - add_cylinder:
+     id: 0
+     center: [22.5, 22.5, 22.5]
+     axis: [1, 0, 1]
+     radius: 39
+     angular_velocity: [0,0.05,0]
+
+
+compute_force:
+  - gravity_force
+  - compute_hooke_interaction:
+     config: { rcut: 0.0 m , dncut: 0.0 m, kn: 10000, kt: 8000, kr: 0.0, fc: 0.0, mu: 0.1, damp_rate: 0.999} 
+     config_driver: { rcut: 0.0 m , dncut: 0.0 m, kn: 10000, kt: 8000, kr: 0.0, fc: 0.0, mu: 0.5, damp_rate: 0.999} 
+
+domain:
+  cell_size: 2 m
+  periodic: [false,true,false]
+
+write_vtklegacy:
+  ascii: true
+  ghost: false
+
+global:
+  simulation_dump_frequency: -1
+  simulation_end_iteration: 1000000
+  simulation_log_frequency: 1000
+  simulation_paraview_frequency: 5000
+  dt: 0.0001 s 
+  rcut_inc: 0.05 m
+  enable_stl_mesh: true
diff --git a/example/polyhedra/stl_mesh/CMakeLists.txt b/example/polyhedra/stl_mesh/CMakeLists.txt
index 46ab16a..6375bb5 100644
--- a/example/polyhedra/stl_mesh/CMakeLists.txt
+++ b/example/polyhedra/stl_mesh/CMakeLists.txt
@@ -5,6 +5,7 @@ set(FileName "stl_mesh_box_hexapod_mini.msp")
 file(COPY ${CMAKE_CURRENT_SOURCE_DIR}/alpha3.shp DESTINATION ${CMAKE_CURRENT_BINARY_DIR})
 file(COPY ${CMAKE_CURRENT_SOURCE_DIR}/octahedron.shp DESTINATION ${CMAKE_CURRENT_BINARY_DIR})
 file(COPY ${CMAKE_CURRENT_SOURCE_DIR}/box.stl DESTINATION ${CMAKE_CURRENT_BINARY_DIR})
+file(COPY ${CMAKE_CURRENT_SOURCE_DIR}/box_mixte.stl DESTINATION ${CMAKE_CURRENT_BINARY_DIR})
 file(COPY ${CMAKE_CURRENT_SOURCE_DIR}/box_for_octa.stl DESTINATION ${CMAKE_CURRENT_BINARY_DIR})
 
 add_test(Example_ExaDEM_${ExampleName} ${CMAKE_BINARY_DIR}/exaDEM ${CMAKE_CURRENT_SOURCE_DIR}/${FileName} --omp_num_threads 1)
@@ -17,3 +18,10 @@ set(FileName "stl_mesh_box_octahedron_mini.msp")
 add_test(Example_ExaDEM_${ExampleName} ${CMAKE_BINARY_DIR}/exaDEM ${CMAKE_CURRENT_SOURCE_DIR}/${FileName} --omp_num_threads 1)
 add_test(Example_ExaDEM_${ExampleName}_omp ${CMAKE_BINARY_DIR}/exaDEM ${CMAKE_CURRENT_SOURCE_DIR}/${FileName} --omp_num_threads 2)
 add_test(Example_ExaDEM_${ExampleName}_mpi mpirun -n 2 ${CMAKE_BINARY_DIR}/exaDEM ${CMAKE_CURRENT_SOURCE_DIR}/${FileName} --omp_num_threads 1)
+
+set(ExampleName "STLMeshOctahedraHexapods")
+set(FileName "stl_mesh_box_mixte_mini.msp")
+
+add_test(Example_ExaDEM_${ExampleName} ${CMAKE_BINARY_DIR}/exaDEM ${CMAKE_CURRENT_SOURCE_DIR}/${FileName} --omp_num_threads 1)
+add_test(Example_ExaDEM_${ExampleName}_omp ${CMAKE_BINARY_DIR}/exaDEM ${CMAKE_CURRENT_SOURCE_DIR}/${FileName} --omp_num_threads 2)
+add_test(Example_ExaDEM_${ExampleName}_mpi mpirun -n 2 ${CMAKE_BINARY_DIR}/exaDEM ${CMAKE_CURRENT_SOURCE_DIR}/${FileName} --omp_num_threads 1)
\ No newline at end of file
diff --git a/example/polyhedra/stl_mesh/box_mixte.stl b/example/polyhedra/stl_mesh/box_mixte.stl
new file mode 100644
index 0000000..2d3f23c
--- /dev/null
+++ b/example/polyhedra/stl_mesh/box_mixte.stl
@@ -0,0 +1,73 @@
+solid Created by Gmsh
+facet normal -1 0 0
+  outer loop
+    vertex -1 -1 19
+    vertex -1 19 -1
+    vertex -1 -1 -1
+  endloop
+endfacet
+facet normal -1 0 0
+  outer loop
+    vertex -1 -1 19
+    vertex -1 19 19
+    vertex -1 19 -1
+  endloop
+endfacet
+facet normal 1 0 0
+  outer loop
+    vertex 19 -1 19
+    vertex 19 -1 -1
+    vertex 19 19 -1
+  endloop
+endfacet
+facet normal 1 -0 0
+  outer loop
+    vertex 19 -1 19
+    vertex 19 19 -1
+    vertex 19 19 19
+  endloop
+endfacet
+facet normal 0 -1 -0
+  outer loop
+    vertex 19 -1 19
+    vertex -1 -1 -1
+    vertex 19 -1 -1
+  endloop
+endfacet
+facet normal -0 -1 0
+  outer loop
+    vertex 19 -1 19
+    vertex -1 -1 19
+    vertex -1 -1 -1
+  endloop
+endfacet
+facet normal 0 1 0
+  outer loop
+    vertex 19 19 19
+    vertex 19 19 -1
+    vertex -1 19 -1
+  endloop
+endfacet
+facet normal 0 1 0
+  outer loop
+    vertex 19 19 19
+    vertex -1 19 -1
+    vertex -1 19 19
+  endloop
+endfacet
+facet normal -0 0 -1
+  outer loop
+    vertex 19 19 -1
+    vertex -1 -1 -1
+    vertex -1 19 -1
+  endloop
+endfacet
+facet normal 0 -0 -1
+  outer loop
+    vertex 19 19 -1
+    vertex 19 -1 -1
+    vertex -1 -1 -1
+  endloop
+endfacet
+
+endsolid Created by Gmsh
diff --git a/example/polyhedra/stl_mesh/stl_mesh_box_mixte.msp b/example/polyhedra/stl_mesh/stl_mesh_box_mixte.msp
new file mode 100644
index 0000000..0cc04ec
--- /dev/null
+++ b/example/polyhedra/stl_mesh/stl_mesh_box_mixte.msp
@@ -0,0 +1,59 @@
+grid_flavor: grid_flavor_dem
+
+includes:
+  - config_polyhedra.msp
+
+input_data:
+  - lattice:
+      structure: BCC
+      types: [ 0 , 1 ]
+      size: [ 1.5 , 1.5 , 1.5 ]
+      repeats: [ 12 , 12 , 40 ]
+      enlarge_bounds: 0.0 m
+  - read_shape_file:
+     filename: alpha3.shp
+  - read_shape_file:
+     filename: octahedron.shp
+  - polyhedra_define_radius
+  - polyhedra_set_density
+  - set_rand_velocity:
+     var: 0.1
+     mean: [0.0,0.0,0.0]
+  - set_rand_vrot_arot
+  - set_quaternion
+  - polyhedra_update_inertia
+
+
+input_data:
+  - reader1
+
+setup_drivers:
+  - add_stl_mesh:
+     id: 0
+     filename: box_mixte.stl
+     minskowski: 0.01
+  - update_grid_stl_mesh
+
+
+compute_force:
+  - gravity_force
+  - compute_hooke_interaction:
+     config: { rcut: 0.0 m , dncut: 0.0 m, kn: 10000, kt: 8000, kr: 0.0, fc: 0.0, mu: 0.1, damp_rate: 0.999} 
+     config_driver: { rcut: 0.0 m , dncut: 0.0 m, kn: 10000, kt: 8000, kr: 0.0, fc: 0.0, mu: 0.5, damp_rate: 0.999} 
+
+domain:
+  cell_size: 2 m
+  periodic: [false,false,false]
+
+write_vtklegacy:
+  ascii: true
+  ghost: false
+
+global:
+  simulation_dump_frequency: -1
+  simulation_end_iteration: 100000
+  simulation_log_frequency: 1000
+  simulation_paraview_frequency: 1000
+  dt: 0.0001 s 
+  rcut_inc: 0.1 m
+  enable_stl_mesh: true
diff --git a/example/polyhedra/stl_mesh/stl_mesh_box_mixte_mini.msp b/example/polyhedra/stl_mesh/stl_mesh_box_mixte_mini.msp
new file mode 100644
index 0000000..ca686f9
--- /dev/null
+++ b/example/polyhedra/stl_mesh/stl_mesh_box_mixte_mini.msp
@@ -0,0 +1,59 @@
+grid_flavor: grid_flavor_dem
+
+includes:
+  - config_polyhedra.msp
+
+input_data:
+  - lattice:
+      structure: BCC
+      types: [ 0 , 1 ]
+      size: [ 1.5 , 1.5 , 1.5 ]
+      repeats: [ 5 , 5 , 5 ]
+      enlarge_bounds: 0.0 m
+  - read_shape_file:
+     filename: alpha3.shp
+  - read_shape_file:
+     filename: octahedron.shp
+  - polyhedra_define_radius
+  - polyhedra_set_density
+  - set_rand_velocity:
+     var: 0.1
+     mean: [0.0,0.0,0.0]
+  - set_rand_vrot_arot
+  - set_quaternion
+  - polyhedra_update_inertia
+
+
+input_data:
+  - reader1
+
+setup_drivers:
+  - add_stl_mesh:
+     id: 0
+     filename: box_mixte.stl
+     minskowski: 0.01
+  - update_grid_stl_mesh
+
+
+compute_force:
+  - gravity_force
+  - compute_hooke_interaction:
+     config: { rcut: 0.0 m , dncut: 0.0 m, kn: 10000, kt: 8000, kr: 0.0, fc: 0.0, mu: 0.1, damp_rate: 0.999} 
+     config_driver: { rcut: 0.0 m , dncut: 0.0 m, kn: 10000, kt: 8000, kr: 0.0, fc: 0.0, mu: 0.5, damp_rate: 0.999} 
+
+domain:
+  cell_size: 2 m
+  periodic: [false,false,false]
+
+write_vtklegacy:
+  ascii: true
+  ghost: false
+
+global:
+  simulation_dump_frequency: -1
+  simulation_end_iteration: 12000
+  simulation_log_frequency: 1000
+  simulation_paraview_frequency: -1
+  dt: 0.0001 s 
+  rcut_inc: 0.05 m
+  enable_stl_mesh: true
diff --git a/src/polyhedra/include/exaDEM/compute_hooke_interaction.h b/src/polyhedra/include/exaDEM/compute_hooke_interaction.h
index a451243..77681ac 100644
--- a/src/polyhedra/include/exaDEM/compute_hooke_interaction.h
+++ b/src/polyhedra/include/exaDEM/compute_hooke_interaction.h
@@ -87,13 +87,12 @@ namespace exaDEM
 				const Vec3d r_i       = { cell[field::rx][p_i], cell[field::ry][p_i], cell[field::rz][p_i] };
 				// === vrot
 				const Vec3d& vrot_i  = cell[field::vrot][p_i];
-				const auto& t_i  = cell[field::type][p_i];
 				const Quaternion& orient_i  = cell[field::orient][p_i];
 				const auto& shp_j = driver.shp;
 
 				// WARNING
 				const Quaternion orient_j = {1.0,0.0,0.0,0.0};
-				auto [contact, dn, n, contact_position] = func(I.type, r_i, sub_i, &shp_i[t_i], orient_i, driver.center, sub_j, &shp_j, orient_j);
+				auto [contact, dn, n, contact_position] = func(I.type, r_i, sub_i, shp_i, orient_i, driver.center, sub_j, &shp_j, orient_j);
 
 				if(contact)
 				{