test strain

tests/test_laminate_strains.py

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+'''
+Test of strains of LaminateStrength
+===================================
+ 
+Test LaminateStrength class using examples from reference 1
+
+References
+----------
+1 - https://ntrs.nasa.gov/api/citations/19950009349/downloads/19950009349.pdf
+'''
+
+import pytest
+import numpy as np
+import pandas as pd
+
+from composipy import OrthotropicMaterial, LaminateProperty, LaminateStrength
+
+
+@pytest.fixture
+def laminateconfig():
+    '''
+    Material configuration from Example 1 in page 31.
+    Laminate configuration from Example 3 in page 46
+    This laminate is used in all tests
+    '''
+    E1 = 2.01e7 #lb/in2
+    E2 = 1.301e6 #lb/in2
+    v12 = 0.3
+    G12 = 1.001e6 #lb/in2
+    t = 0.005 #in
+    material = OrthotropicMaterial(E1, E2, v12, G12, t)
+    stacking = [0, 45, 45, 0]
+    return LaminateProperty(stacking, material)
+
+
+@pytest.fixture
+def example_3_setup(laminateconfig):
+    '''
+    Example 3 setup in page 46
+    '''
+    Nxx = 500 #lb/in
+    return LaminateStrength(dproperty=laminateconfig, Nxx=Nxx)
+
+
+@pytest.fixture
+def example_6_setup(laminateconfig):
+    '''
+    Example 6 setup in page 56
+    '''
+    Mxx = 5 #lb/in
+    return LaminateStrength(dproperty=laminateconfig, Mxx=Mxx)
+
+
+def test_example_3_midplane(example_3_setup):
+    '''This test check the stains at the midplane'''
+    calculated_strains = example_3_setup.epsilon0()
+    reference_result = np.array([0.00221, -0.0007, -0.00115, 0, 0, 0])
+    np.testing.assert_allclose(calculated_strains, reference_result, rtol=1e-2, atol=1e-4)
+
+
+def test_example_3_strain_45(example_3_setup):
+    '''This test check the stains for the 45° plies in material direction'''
+    df_strains = example_3_setup.calculate_strain()
+    epsilon1 = df_strains.iloc[2]['epsilon1']
+    epsilon2 = df_strains.iloc[2]['epsilon2']
+    gamma12 = df_strains.iloc[2]['gamma12']
+    assert np.isclose(epsilon1, 0.00018, rtol=1e-3, atol=1e-4)
+    assert np.isclose(epsilon2, 0.00133, rtol=1e-3, atol=1e-4)
+    assert np.isclose(gamma12, -0.00291, rtol=1e-3, atol=1e-4)
+
+
+def test_example_3_stress_45(example_3_setup):
+    '''This test check the stresses for the 45° plies in material direction'''
+    df_stresses = example_3_setup.calculate_stress()
+    sigma1 = df_stresses.iloc[2]['sigma1']
+    sigma2 = df_stresses.iloc[2]['sigma2']
+    tau12 = df_stresses.iloc[2]['tau12']
+    assert np.isclose(sigma1, 4146, rtol=1e-3, atol=100)
+    assert np.isclose(sigma2, 1812, rtol=1e-3, atol=100)
+    assert np.isclose(tau12, -2913, rtol=1e-3, atol=100)
+
+
+def test_example_6_midplane(example_6_setup):
+    '''This test check the stains at the midplane eq E6.1'''
+    calculated_strains = example_6_setup.epsilon0()
+    reference_result = np.array([0, 0, 0, 0.418, -0.165, -0.0975])
+    np.testing.assert_allclose(calculated_strains, reference_result, rtol=1e-2, atol=1e-4)
+
+
+def test_example_6_strain_top_ply1(example_6_setup):
+    '''This test check the stains at the top of ply 1 in laminate direction'''
+    df_strains = example_6_setup.calculate_strain()
+    epsilonx = df_strains.iloc[0]['epsilonx']
+    epsilony = df_strains.iloc[0]['epsilony']
+    gammaxy = df_strains.iloc[0]['gammaxy']
+    assert np.isclose(epsilonx, 0.00418, rtol=1e-3, atol=1e-4)
+    assert np.isclose(epsilony, -0.00165, rtol=1e-3, atol=1e-4)
+    assert np.isclose(gammaxy, -0.000975, rtol=1e-3, atol=1e-4)
+
+
+def test_example_6_strain_top_ply2(example_6_setup):
+    '''This test check the stains at the top of ply 1 in material direction'''
+    df_strains = example_6_setup.calculate_strain()
+    epsilon1 = df_strains.iloc[2]['epsilon1']
+    epsilon2 = df_strains.iloc[2]['epsilon2']
+    gamma12 = df_strains.iloc[2]['gamma12']
+    assert np.isclose(epsilon1, 0.00039, rtol=1e-3, atol=1e-4)
+    assert np.isclose(epsilon2, 0.00088, rtol=1e-3, atol=1e-4)
+    assert np.isclose(gamma12, -0.00292, rtol=1e-3, atol=1e-4)
+
+
+def test_example_6_stress_bot_ply3(example_6_setup):
+    '''This test check the stresses for the ply 3 in material direction E6.12'''
+    df_stresses = example_6_setup.calculate_stress()
+    sigma1 = df_stresses.iloc[5]['sigma1']
+    sigma2 = df_stresses.iloc[5]['sigma2']
+    tau12 = df_stresses.iloc[5]['tau12']
+    assert np.isclose(sigma1, -8094, rtol=1e-3, atol=100)
+    assert np.isclose(sigma2, -1296, rtol=1e-3, atol=100)
+    assert np.isclose(tau12, 2923, rtol=1e-3, atol=100)