def test_offsets():
"""Offsets should not influence the result."""
B = 100
H = 20
E = 210000
sections = ((B, H, 0, E), )
sections2 = ((B, H, 12.435, E), )
EI, top, bot = bm.EI(sections, E)
EI2, top2, bot2 = bm.EI(sections2, E)
assert 0.99 < EI / EI2 < 1.01
assert 0.99 < top / top2 < 1.01
assert 0.99 < bot / bot2 < 1.01
def test_uneven_sw():
"""Sandwich with different top and bottom layer width."""
B = 100
t = 1
H = 30
E = 20000
sections = ((2 * B, t, 0, E), (B, t, H - t, E))
EI, top, bot = bm.EI(sections, E)
assert 1.95 < abs(bot) / top < 1.96
def test_simple():
"""The most simple case; a single rectangle."""
B = 100
H = 20
E = 210000
sections = ((B, H, 0, E), )
EI, top, bot = bm.EI(sections, E)
EIc = E * B * (H**3) / 12
assert 0.99 < EI / EIc < 1.01
assert top == H / 2
assert bot == -H / 2
def test_sw2():
"""Sandwich with different E for top and bottom layer"""
B1 = 100
B2 = 200
h = 18
t = 1
H = h + 2 * t
E1 = 20000
E2 = 10000
sections = ((B1, t, 0, E1), (B2, t, h + t, E2))
EI, top, bot = bm.EI(sections, E1)
EIc = E1 * B1 * (H**3 - h**3) / 12
assert 0.99 < EI / EIc < 1.01
def test_simple_sw():
"""Simple sandwich"""
B = 100
h = 18
t = 1
H = h + 2 * t
E = 20000
sections = ((B, t, 0, E), (B, t, h + t, E))
EI, top, bot = bm.EI(sections, E)
EIc = E * B * (H**3 - h**3) / 12
assert 0.99 < EI / EIc < 1.01
assert top == H / 2
assert bot == -H / 2