[GeoMechanicsApplication] Revisit and document test element lab

applications/GeoMechanicsApplication/custom_strategies/schemes/README.md

@@ -13,7 +13,7 @@ It also has a general `Update` step, which calls the `UpdateVariablesDerivatives
 ![SchemeStructure.svg](SchemeStructure.svg)
 _Class structure of the schemes generated using the SchemeStructure.puml file with PlantUML. Note that the class diagram is simplified and only shows the functions that need emphasis._
 
-The child classes which actually specify which variables are used in the time integration scheme (e.g. the `BackwardEulerUPwScheme` or the `GeneralizedNewmarkTScheme), only fill the lists of first/second order variables. 
+The child classes which actually specify which variables are used in the time integration scheme (e.g. the `BackwardEulerUPwScheme` or the `GeneralizedNewmarkTScheme`), only fill the lists of first/second order variables. 
 
 The exceptions are the `NewmarkQuasistaticUPwScheme`, which has functionality for nodal smoothing (this should be moved to another location) and the damped and dynamic UPw schemes. More info on these can be found in the [Dynamic and damped schemes](#dynamic-and-damped-schemes) section. 
 
@@ -38,13 +38,13 @@ The time factors are set in the `SetTimeFactors` function, which sets the coeffi
 ## Generalized Newmark
 A bit more involved are the Generalized Newmark schemes. This includes more parameters to tweak and has a more complex set of equations. The functionality described in this section can be found in the `GeneralizedNewmarkScheme` class. This results in the following three equations for updating the scalar and vector derivatives.
 
-First time derivative for scalar variables in `UpdateScalarTimeDerivative`:
+First time derivative for scalar variables in `UpdateScalarTimeDerivative`, known as GN11:
 $$\dot{x}\_{t + \Delta t} = \frac{x\_{t + \Delta t} - x\_{t} - (1 - \theta) \Delta t \dot{x}\_{t}}{\theta \Delta t}$$
 
-Second time derivative for vector variables in `UpdateVectorSecondTimeDerivative`:
+Second time derivative for vector variables in `UpdateVectorSecondTimeDerivative`, known as GN22:
 $$\ddot{x}\_{t + \Delta t} = \frac{x\_{t + \Delta t} - x\_{t} - \Delta t \dot{x}\_{t} - (0.5 - \beta)(\Delta t)^{2}\ddot{x}\_{t}}{\beta(\Delta t)^{2}}$$
 
-First time derivative for vector variables in `UpdateVectorFirstTimeDerivative`:
+First time derivative for vector variables in `UpdateVectorFirstTimeDerivative`, known as GN22:
 $$\dot{x}\_{t + \Delta t} = \dot{x}\_{t} + (1 - \gamma)\Delta t \ddot{x}\_{t} + \gamma \Delta t \ddot{x}\_{t + \Delta t}$$
 
 Note that the order here is the other reversed with respect to the Backward Euler scheme. This is because $\ddot{x}\_{t + \Delta t}$ is used in the equation for $\dot{x}\_{t + \Delta t}$.

applications/GeoMechanicsApplication/tests/test_element_lab.py

@@ -5,7 +5,7 @@
 
 class KratosGeoMechanicsLabElementTests(KratosUnittest.TestCase):
     """
-    This class contains some element tests, such as triaxial and oedoemter tests
+    This class contains some element tests, such as triaxial and oedometer tests
     """
 
     def setUp(self):
@@ -21,7 +21,7 @@ def test_triaxial_comp_6n(self):
         Drained compression triaxial test on Mohr-Coulomb model with axisymmetric 2D6N elements
         It consistes of two calculation phases:
         1) apply confining stress of -100 kPa
-        2) apply deviatoric stress of 200 kPa
+        2) apply deviatoric stress of -200 kPa
         """
         test_name = 'triaxial_comp_6n'
         project_path = test_helper.get_file_path(os.path.join('test_element_lab', test_name))
@@ -61,14 +61,12 @@ def test_triaxial_comp_6n(self):
 
     def test_oedometer_ULFEM(self):
         """
-        Oedometer test on Mohr-Coulomb model with 2D6N elements
+        Oedometer test on a linear elastic model with 2D6N elements
         """
         test_name = 'oedometer_ULFEM'
         project_path = test_helper.get_file_path(os.path.join('test_element_lab', test_name))
         simulation = test_helper.run_kratos(project_path)
         effective_stresses = test_helper.get_cauchy_stress_tensor(simulation)
-        displacements = test_helper.get_displacement(simulation)
-
         effective_stresses_xx = [integration_point[0,0] for element in effective_stresses for integration_point in element]
         effective_stresses_yy = [integration_point[1,1] for element in effective_stresses for integration_point in element]
         effective_stresses_zz = [integration_point[2,2] for element in effective_stresses for integration_point in element]
@@ -79,14 +77,28 @@ def test_oedometer_ULFEM(self):
             self.assertAlmostEqual(-1000000, effective_stresses_yy[idx], 2)
             self.assertAlmostEqual(0.0,      effective_stresses_zz[idx], 3)
 
-        y_displacements = [displacement[1] for displacement in displacements]
-        top_node_nbrs = [1]
-        for top_node_nbr in top_node_nbrs:
-            self.assertAlmostEqual(-0.0909090909516868, y_displacements[top_node_nbr], 6)
+        top_node_nbrs = [1, 2]
+        output_file_path = os.path.join(project_path, test_name+'.post.res')
+        output_reader = test_helper.GiDOutputFileReader()
+        output_data = output_reader.read_output_from(output_file_path)
+        displacements = test_helper.GiDOutputFileReader.nodal_values_at_time("DISPLACEMENT", 0.1, output_data, node_ids=top_node_nbrs)
+        for displacement in displacements:
+            y_displacement = displacement[1]
+            self.assertAlmostEqual(-0.00990099, y_displacement, 6)
+
+        displacements = test_helper.GiDOutputFileReader.nodal_values_at_time("DISPLACEMENT", 0.7, output_data, node_ids=top_node_nbrs)
+        for displacement in displacements:
+            y_displacement = displacement[1]
+            self.assertAlmostEqual(-0.0654206, y_displacement, 6)
+
+        displacements = test_helper.GiDOutputFileReader.nodal_values_at_time("DISPLACEMENT", 1.0, output_data, node_ids=top_node_nbrs)
+        for displacement in displacements:
+            y_displacement = displacement[1]
+            self.assertAlmostEqual(-0.0909090909516868, y_displacement, 6)
 
     def test_oedometer_ULFEM_diff_order(self):
         """
-        Oedometer test on Mohr-Coulomb model with 2D6N with different order elements
+        Oedometer test on a linear elastic model with 2D6N with different order elements
         """
         test_name = 'oedometer_ULFEM_diff_order'
         project_path = test_helper.get_file_path(os.path.join('test_element_lab', test_name))
@@ -107,7 +119,7 @@ def test_oedometer_ULFEM_diff_order(self):
         y_displacements = [displacement[1] for displacement in displacements]
         top_node_nbrs = [1]
         for top_node_nbr in top_node_nbrs:
-            self.assertAlmostEqual(-9.999000099991246e-05, y_displacements[top_node_nbr], 6)
+            self.assertAlmostEqual(-1e-04, y_displacements[top_node_nbr], 6)
 
 if __name__ == '__main__':
     KratosUnittest.main()