FEM: unit tests, add tests for von mises and prinzipal stress calculation

src/Mod/Fem/femtest/testresult.py

@@ -222,6 +222,36 @@ class TestResult(unittest.TestCase):
         self.assertEqual(read_mflow, expected_mflow, "Values of read mflow result data are unexpected")
         self.assertEqual(read_npressure, expected_npressure, "Values of read npressure result data are unexpected")
 
+    def get_stress_values(self):
+        # node 5 von calculix cantilver 3D example
+        # doc = FreeCAD.open(FreeCAD.ConfigGet("AppHomePath") + 'data/examples/FemCalculixCantilever3D.FCStd')
+        # doc.Box_Mesh.FemMesh.Nodes[5]
+        # Vector (0.0, 1000.0, 0.0)
+        stress = (
+            -4.52840E+02,  # S11
+            -1.94075E+02,  # S22
+            -1.94075E+02,  # S33
+            6.11223E+01,  # S12
+            6.92759E-05,  # S23
+            -2.60754E+01  # S31
+        )  # run an analysis and copy the values from frd result file
+        return stress
+
+    def test_stress_von_mises(self):
+        expected_mises = 283.2082
+        from feminout.importToolsFem import calculate_von_mises as vm
+        mises = vm(self.get_stress_values())
+        # fcc_print(round(mises, 4))
+        self.assertEqual(round(mises, 4), expected_mises, "Calculated von Mises stress is not the expected value.")
+
+    def test_stress_principal(self):
+        expected_principal = (-178.0076, -194.0749, -468.9075, 145.4499)
+        from feminout.importToolsFem import calculate_principal_stress as pr
+        prin = pr(self.get_stress_values())
+        rounded_prin = (round(prin[0], 4), round(prin[1], 4), round(prin[2], 4), round(prin[3], 4))
+        # fcc_print(rounded_prin)
+        self.assertEqual(rounded_prin, expected_principal, "Calculated principal stresses are not the expected values.")
+
     def tearDown(self):
         FreeCAD.closeDocument(self.doc_name)
         pass