def test_constant_vs_quadratic_tensile_slip():
""" Compare constant and quadratic slip elements"""
n_elements = 1
mu = np.array([3e10])
nu = np.array([0.25])
elements = []
element = {}
L = 10000
x1, y1, x2, y2 = bem2d.discretized_line(-L, 0, L, 0, n_elements)
for i in range(0, x1.size):
element["x1"] = x1[i]
element["y1"] = y1[i]
element["x2"] = x2[i]
element["y2"] = y2[i]
elements.append(element.copy())
elements = bem2d.standardize_elements(elements)
# Observation coordinates for far-field calculation
n_pts = 100
width = 20000
x = np.linspace(-width, width, n_pts)
y = np.linspace(-width, width, n_pts)
x, y = np.meshgrid(x, y)
x = x.flatten()
y = y.flatten()
# Just a simple forward model for the volume
displacement_constant_slip = np.zeros((2, x.size))
stress_constant_slip = np.zeros((3, x.size))
displacement_quadratic_slip = np.zeros((2, x.size))
stress_quadratic_slip = np.zeros((3, x.size))
for i, element in enumerate(elements):
displacement, stress = bem2d.displacements_stresses_constant_linear(
x,
y,
element["half_length"],
mu,
nu,
"constant",
"slip",
0,
1,
element["x_center"],
element["y_center"],
element["rotation_matrix"],
element["inverse_rotation_matrix"],
)
displacement_constant_slip += displacement
stress_constant_slip += stress
for element in elements:
quadratic_coefficients = np.array(
[1, 1, 1]) # constant slip quadratic element
displacement, stress = bem2d.displacements_stresses_quadratic_farfield_coefficients(
quadratic_coefficients,
x,
y,
element["half_length"],
mu,
nu,
"slip",
0,
1,
element["x_center"],
element["y_center"],
element["rotation_matrix"],
element["inverse_rotation_matrix"],
)
displacement_quadratic_slip += displacement
stress_quadratic_slip += stress
np.testing.assert_almost_equal(displacement_constant_slip,
displacement_quadratic_slip)
np.testing.assert_almost_equal(stress_constant_slip,
stress_quadratic_slip,
decimal=1)
displacement_constant_slip = np.zeros((2, x.size))
stress_constant_slip = np.zeros((3, x.size))
displacement_quadratic = np.zeros((2, x.size))
stress_quadratic = np.zeros((3, x.size))
# slip_linear = np.linspace(-1, 1, len(elements))
for i, element in enumerate(elements):
displacement, stress = bem2d.displacements_stresses_constant_linear(
x,
y,
element["half_length"],
mu,
nu,
"constant",
"slip",
0,
1,
element["x_center"],
element["y_center"],
element["rotation_matrix"],
element["inverse_rotation_matrix"],
)
displacement_constant_slip += displacement
stress_constant_slip += stress
bem2d.plot_fields(
elements,
x.reshape(n_pts, n_pts),
y.reshape(n_pts, n_pts),
displacement_constant_slip,
#
# Internal evaluation for constant BEM
#
fault_slip_ss = fault_slip[0::2]
fault_slip_ts = fault_slip[1::2]
displacement_full_space = np.zeros((2, x.size))
stress_full_space = np.zeros((3, x.size))
for i, element in enumerate(elements_fault):
displacement, stress = bem2d.displacements_stresses_constant_linear(
x,
y,
element["half_length"],
mu,
nu,
"constant",
"slip",
fault_slip_ss[i].copy(),
fault_slip_ts[i].copy(),
element["x_center"],
element["y_center"],
element["rotation_matrix"],
element["inverse_rotation_matrix"],
)
displacement_full_space += displacement
stress_full_space += stress
bem2d.plot_fields(
elements_surface + elements_fault,
x.reshape(n_pts, n_pts),
y.reshape(n_pts, n_pts),
displacement_full_space,