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MTtranslateService/Lib/site-packages/sympy/physics/continuum_mechanics/tests/test_beam.py

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from sympy.core.function import expand
from sympy.core.numbers import (Rational, pi)
from sympy.core.singleton import S
from sympy.core.symbol import (Symbol, symbols)
from sympy.sets.sets import Interval
from sympy.simplify.simplify import simplify
from sympy.physics.continuum_mechanics.beam import Beam
from sympy.functions import SingularityFunction, Piecewise, meijerg, Abs, log
from sympy.testing.pytest import raises
from sympy.physics.units import meter, newton, kilo, giga, milli
from sympy.physics.continuum_mechanics.beam import Beam3D
from sympy.geometry import Circle, Polygon, Point2D, Triangle
from sympy.core.sympify import sympify
x = Symbol('x')
y = Symbol('y')
R1, R2 = symbols('R1, R2')
def test_Beam():
E = Symbol('E')
E_1 = Symbol('E_1')
I = Symbol('I')
I_1 = Symbol('I_1')
A = Symbol('A')
b = Beam(1, E, I)
assert b.length == 1
assert b.elastic_modulus == E
assert b.second_moment == I
assert b.variable == x
# Test the length setter
b.length = 4
assert b.length == 4
# Test the E setter
b.elastic_modulus = E_1
assert b.elastic_modulus == E_1
# Test the I setter
b.second_moment = I_1
assert b.second_moment is I_1
# Test the variable setter
b.variable = y
assert b.variable is y
# Test for all boundary conditions.
b.bc_deflection = [(0, 2)]
b.bc_slope = [(0, 1)]
assert b.boundary_conditions == {'deflection': [(0, 2)], 'slope': [(0, 1)]}
# Test for slope boundary condition method
b.bc_slope.extend([(4, 3), (5, 0)])
s_bcs = b.bc_slope
assert s_bcs == [(0, 1), (4, 3), (5, 0)]
# Test for deflection boundary condition method
b.bc_deflection.extend([(4, 3), (5, 0)])
d_bcs = b.bc_deflection
assert d_bcs == [(0, 2), (4, 3), (5, 0)]
# Test for updated boundary conditions
bcs_new = b.boundary_conditions
assert bcs_new == {
'deflection': [(0, 2), (4, 3), (5, 0)],
'slope': [(0, 1), (4, 3), (5, 0)]}
b1 = Beam(30, E, I)
b1.apply_load(-8, 0, -1)
b1.apply_load(R1, 10, -1)
b1.apply_load(R2, 30, -1)
b1.apply_load(120, 30, -2)
b1.bc_deflection = [(10, 0), (30, 0)]
b1.solve_for_reaction_loads(R1, R2)
# Test for finding reaction forces
p = b1.reaction_loads
q = {R1: 6, R2: 2}
assert p == q
# Test for load distribution function.
p = b1.load
q = -8*SingularityFunction(x, 0, -1) + 6*SingularityFunction(x, 10, -1) \
+ 120*SingularityFunction(x, 30, -2) + 2*SingularityFunction(x, 30, -1)
assert p == q
# Test for shear force distribution function
p = b1.shear_force()
q = 8*SingularityFunction(x, 0, 0) - 6*SingularityFunction(x, 10, 0) \
- 120*SingularityFunction(x, 30, -1) - 2*SingularityFunction(x, 30, 0)
assert p == q
# Test for shear stress distribution function
p = b1.shear_stress()
q = (8*SingularityFunction(x, 0, 0) - 6*SingularityFunction(x, 10, 0) \
- 120*SingularityFunction(x, 30, -1) \
- 2*SingularityFunction(x, 30, 0))/A
assert p==q
# Test for bending moment distribution function
p = b1.bending_moment()
q = 8*SingularityFunction(x, 0, 1) - 6*SingularityFunction(x, 10, 1) \
- 120*SingularityFunction(x, 30, 0) - 2*SingularityFunction(x, 30, 1)
assert p == q
# Test for slope distribution function
p = b1.slope()
q = -4*SingularityFunction(x, 0, 2) + 3*SingularityFunction(x, 10, 2) \
+ 120*SingularityFunction(x, 30, 1) + SingularityFunction(x, 30, 2) \
+ Rational(4000, 3)
assert p == q/(E*I)
# Test for deflection distribution function
p = b1.deflection()
q = x*Rational(4000, 3) - 4*SingularityFunction(x, 0, 3)/3 \
+ SingularityFunction(x, 10, 3) + 60*SingularityFunction(x, 30, 2) \
+ SingularityFunction(x, 30, 3)/3 - 12000
assert p == q/(E*I)
# Test using symbols
l = Symbol('l')
w0 = Symbol('w0')
w2 = Symbol('w2')
a1 = Symbol('a1')
c = Symbol('c')
c1 = Symbol('c1')
d = Symbol('d')
e = Symbol('e')
f = Symbol('f')
b2 = Beam(l, E, I)
b2.apply_load(w0, a1, 1)
b2.apply_load(w2, c1, -1)
b2.bc_deflection = [(c, d)]
b2.bc_slope = [(e, f)]
# Test for load distribution function.
p = b2.load
q = w0*SingularityFunction(x, a1, 1) + w2*SingularityFunction(x, c1, -1)
assert p == q
# Test for shear force distribution function
p = b2.shear_force()
q = -w0*SingularityFunction(x, a1, 2)/2 \
- w2*SingularityFunction(x, c1, 0)
assert p == q
# Test for shear stress distribution function
p = b2.shear_stress()
q = (-w0*SingularityFunction(x, a1, 2)/2 \
- w2*SingularityFunction(x, c1, 0))/A
assert p == q
# Test for bending moment distribution function
p = b2.bending_moment()
q = -w0*SingularityFunction(x, a1, 3)/6 - w2*SingularityFunction(x, c1, 1)
assert p == q
# Test for slope distribution function
p = b2.slope()
q = (w0*SingularityFunction(x, a1, 4)/24 + w2*SingularityFunction(x, c1, 2)/2)/(E*I) + (E*I*f - w0*SingularityFunction(e, a1, 4)/24 - w2*SingularityFunction(e, c1, 2)/2)/(E*I)
assert expand(p) == expand(q)
# Test for deflection distribution function
p = b2.deflection()
q = x*(E*I*f - w0*SingularityFunction(e, a1, 4)/24 \
- w2*SingularityFunction(e, c1, 2)/2)/(E*I) \
+ (w0*SingularityFunction(x, a1, 5)/120 \
+ w2*SingularityFunction(x, c1, 3)/6)/(E*I) \
+ (E*I*(-c*f + d) + c*w0*SingularityFunction(e, a1, 4)/24 \
+ c*w2*SingularityFunction(e, c1, 2)/2 \
- w0*SingularityFunction(c, a1, 5)/120 \
- w2*SingularityFunction(c, c1, 3)/6)/(E*I)
assert simplify(p - q) == 0
b3 = Beam(9, E, I, 2)
b3.apply_load(value=-2, start=2, order=2, end=3)
b3.bc_slope.append((0, 2))
C3 = symbols('C3')
C4 = symbols('C4')
p = b3.load
q = -2*SingularityFunction(x, 2, 2) + 2*SingularityFunction(x, 3, 0) \
+ 4*SingularityFunction(x, 3, 1) + 2*SingularityFunction(x, 3, 2)
assert p == q
p = b3.shear_force()
q = 2*SingularityFunction(x, 2, 3)/3 - 2*SingularityFunction(x, 3, 1) \
- 2*SingularityFunction(x, 3, 2) - 2*SingularityFunction(x, 3, 3)/3
assert p == q
p = b3.shear_stress()
q = SingularityFunction(x, 2, 3)/3 - 1*SingularityFunction(x, 3, 1) \
- 1*SingularityFunction(x, 3, 2) - 1*SingularityFunction(x, 3, 3)/3
assert p == q
p = b3.slope()
q = 2 - (SingularityFunction(x, 2, 5)/30 - SingularityFunction(x, 3, 3)/3 \
- SingularityFunction(x, 3, 4)/6 - SingularityFunction(x, 3, 5)/30)/(E*I)
assert p == q
p = b3.deflection()
q = 2*x - (SingularityFunction(x, 2, 6)/180 \
- SingularityFunction(x, 3, 4)/12 - SingularityFunction(x, 3, 5)/30 \
- SingularityFunction(x, 3, 6)/180)/(E*I)
assert p == q + C4
b4 = Beam(4, E, I, 3)
b4.apply_load(-3, 0, 0, end=3)
p = b4.load
q = -3*SingularityFunction(x, 0, 0) + 3*SingularityFunction(x, 3, 0)
assert p == q
p = b4.shear_force()
q = 3*SingularityFunction(x, 0, 1) \
- 3*SingularityFunction(x, 3, 1)
assert p == q
p = b4.shear_stress()
q = SingularityFunction(x, 0, 1) - SingularityFunction(x, 3, 1)
assert p == q
p = b4.slope()
q = -3*SingularityFunction(x, 0, 3)/6 + 3*SingularityFunction(x, 3, 3)/6
assert p == q/(E*I) + C3
p = b4.deflection()
q = -3*SingularityFunction(x, 0, 4)/24 + 3*SingularityFunction(x, 3, 4)/24
assert p == q/(E*I) + C3*x + C4
# can't use end with point loads
raises(ValueError, lambda: b4.apply_load(-3, 0, -1, end=3))
with raises(TypeError):
b4.variable = 1
def test_insufficient_bconditions():
# Test cases when required number of boundary conditions
# are not provided to solve the integration constants.
L = symbols('L', positive=True)
E, I, P, a3, a4 = symbols('E I P a3 a4')
b = Beam(L, E, I, base_char='a')
b.apply_load(R2, L, -1)
b.apply_load(R1, 0, -1)
b.apply_load(-P, L/2, -1)
b.solve_for_reaction_loads(R1, R2)
p = b.slope()
q = P*SingularityFunction(x, 0, 2)/4 - P*SingularityFunction(x, L/2, 2)/2 + P*SingularityFunction(x, L, 2)/4
assert p == q/(E*I) + a3
p = b.deflection()
q = P*SingularityFunction(x, 0, 3)/12 - P*SingularityFunction(x, L/2, 3)/6 + P*SingularityFunction(x, L, 3)/12
assert p == q/(E*I) + a3*x + a4
b.bc_deflection = [(0, 0)]
p = b.deflection()
q = a3*x + P*SingularityFunction(x, 0, 3)/12 - P*SingularityFunction(x, L/2, 3)/6 + P*SingularityFunction(x, L, 3)/12
assert p == q/(E*I)
b.bc_deflection = [(0, 0), (L, 0)]
p = b.deflection()
q = -L**2*P*x/16 + P*SingularityFunction(x, 0, 3)/12 - P*SingularityFunction(x, L/2, 3)/6 + P*SingularityFunction(x, L, 3)/12
assert p == q/(E*I)
def test_statically_indeterminate():
E = Symbol('E')
I = Symbol('I')
M1, M2 = symbols('M1, M2')
F = Symbol('F')
l = Symbol('l', positive=True)
b5 = Beam(l, E, I)
b5.bc_deflection = [(0, 0),(l, 0)]
b5.bc_slope = [(0, 0),(l, 0)]
b5.apply_load(R1, 0, -1)
b5.apply_load(M1, 0, -2)
b5.apply_load(R2, l, -1)
b5.apply_load(M2, l, -2)
b5.apply_load(-F, l/2, -1)
b5.solve_for_reaction_loads(R1, R2, M1, M2)
p = b5.reaction_loads
q = {R1: F/2, R2: F/2, M1: -F*l/8, M2: F*l/8}
assert p == q
def test_beam_units():
E = Symbol('E')
I = Symbol('I')
R1, R2 = symbols('R1, R2')
kN = kilo*newton
gN = giga*newton
b = Beam(8*meter, 200*gN/meter**2, 400*1000000*(milli*meter)**4)
b.apply_load(5*kN, 2*meter, -1)
b.apply_load(R1, 0*meter, -1)
b.apply_load(R2, 8*meter, -1)
b.apply_load(10*kN/meter, 4*meter, 0, end=8*meter)
b.bc_deflection = [(0*meter, 0*meter), (8*meter, 0*meter)]
b.solve_for_reaction_loads(R1, R2)
assert b.reaction_loads == {R1: -13750*newton, R2: -31250*newton}
b = Beam(3*meter, E*newton/meter**2, I*meter**4)
b.apply_load(8*kN, 1*meter, -1)
b.apply_load(R1, 0*meter, -1)
b.apply_load(R2, 3*meter, -1)
b.apply_load(12*kN*meter, 2*meter, -2)
b.bc_deflection = [(0*meter, 0*meter), (3*meter, 0*meter)]
b.solve_for_reaction_loads(R1, R2)
assert b.reaction_loads == {R1: newton*Rational(-28000, 3), R2: newton*Rational(4000, 3)}
assert b.deflection().subs(x, 1*meter) == 62000*meter/(9*E*I)
def test_variable_moment():
E = Symbol('E')
I = Symbol('I')
b = Beam(4, E, 2*(4 - x))
b.apply_load(20, 4, -1)
R, M = symbols('R, M')
b.apply_load(R, 0, -1)
b.apply_load(M, 0, -2)
b.bc_deflection = [(0, 0)]
b.bc_slope = [(0, 0)]
b.solve_for_reaction_loads(R, M)
assert b.slope().expand() == ((10*x*SingularityFunction(x, 0, 0)
- 10*(x - 4)*SingularityFunction(x, 4, 0))/E).expand()
assert b.deflection().expand() == ((5*x**2*SingularityFunction(x, 0, 0)
- 10*Piecewise((0, Abs(x)/4 < 1), (16*meijerg(((3, 1), ()), ((), (2, 0)), x/4), True))
+ 40*SingularityFunction(x, 4, 1))/E).expand()
b = Beam(4, E - x, I)
b.apply_load(20, 4, -1)
R, M = symbols('R, M')
b.apply_load(R, 0, -1)
b.apply_load(M, 0, -2)
b.bc_deflection = [(0, 0)]
b.bc_slope = [(0, 0)]
b.solve_for_reaction_loads(R, M)
assert b.slope().expand() == ((-80*(-log(-E) + log(-E + x))*SingularityFunction(x, 0, 0)
+ 80*(-log(-E + 4) + log(-E + x))*SingularityFunction(x, 4, 0) + 20*(-E*log(-E)
+ E*log(-E + x) + x)*SingularityFunction(x, 0, 0) - 20*(-E*log(-E + 4) + E*log(-E + x)
+ x - 4)*SingularityFunction(x, 4, 0))/I).expand()
def test_composite_beam():
E = Symbol('E')
I = Symbol('I')
b1 = Beam(2, E, 1.5*I)
b2 = Beam(2, E, I)
b = b1.join(b2, "fixed")
b.apply_load(-20, 0, -1)
b.apply_load(80, 0, -2)
b.apply_load(20, 4, -1)
b.bc_slope = [(0, 0)]
b.bc_deflection = [(0, 0)]
assert b.length == 4
assert b.second_moment == Piecewise((1.5*I, x <= 2), (I, x <= 4))
assert b.slope().subs(x, 4) == 120.0/(E*I)
assert b.slope().subs(x, 2) == 80.0/(E*I)
assert int(b.deflection().subs(x, 4).args[0]) == -302 # Coefficient of 1/(E*I)
l = symbols('l', positive=True)
R1, M1, R2, R3, P = symbols('R1 M1 R2 R3 P')
b1 = Beam(2*l, E, I)
b2 = Beam(2*l, E, I)
b = b1.join(b2,"hinge")
b.apply_load(M1, 0, -2)
b.apply_load(R1, 0, -1)
b.apply_load(R2, l, -1)
b.apply_load(R3, 4*l, -1)
b.apply_load(P, 3*l, -1)
b.bc_slope = [(0, 0)]
b.bc_deflection = [(0, 0), (l, 0), (4*l, 0)]
b.solve_for_reaction_loads(M1, R1, R2, R3)
assert b.reaction_loads == {R3: -P/2, R2: P*Rational(-5, 4), M1: -P*l/4, R1: P*Rational(3, 4)}
assert b.slope().subs(x, 3*l) == -7*P*l**2/(48*E*I)
assert b.deflection().subs(x, 2*l) == 7*P*l**3/(24*E*I)
assert b.deflection().subs(x, 3*l) == 5*P*l**3/(16*E*I)
# When beams having same second moment are joined.
b1 = Beam(2, 500, 10)
b2 = Beam(2, 500, 10)
b = b1.join(b2, "fixed")
b.apply_load(M1, 0, -2)
b.apply_load(R1, 0, -1)
b.apply_load(R2, 1, -1)
b.apply_load(R3, 4, -1)
b.apply_load(10, 3, -1)
b.bc_slope = [(0, 0)]
b.bc_deflection = [(0, 0), (1, 0), (4, 0)]
b.solve_for_reaction_loads(M1, R1, R2, R3)
assert b.slope() == -2*SingularityFunction(x, 0, 1)/5625 + SingularityFunction(x, 0, 2)/1875\
- 133*SingularityFunction(x, 1, 2)/135000 + SingularityFunction(x, 3, 2)/1000\
- 37*SingularityFunction(x, 4, 2)/67500
assert b.deflection() == -SingularityFunction(x, 0, 2)/5625 + SingularityFunction(x, 0, 3)/5625\
- 133*SingularityFunction(x, 1, 3)/405000 + SingularityFunction(x, 3, 3)/3000\
- 37*SingularityFunction(x, 4, 3)/202500
def test_point_cflexure():
E = Symbol('E')
I = Symbol('I')
b = Beam(10, E, I)
b.apply_load(-4, 0, -1)
b.apply_load(-46, 6, -1)
b.apply_load(10, 2, -1)
b.apply_load(20, 4, -1)
b.apply_load(3, 6, 0)
assert b.point_cflexure() == [Rational(10, 3)]
def test_remove_load():
E = Symbol('E')
I = Symbol('I')
b = Beam(4, E, I)
try:
b.remove_load(2, 1, -1)
# As no load is applied on beam, ValueError should be returned.
except ValueError:
assert True
else:
assert False
b.apply_load(-3, 0, -2)
b.apply_load(4, 2, -1)
b.apply_load(-2, 2, 2, end = 3)
b.remove_load(-2, 2, 2, end = 3)
assert b.load == -3*SingularityFunction(x, 0, -2) + 4*SingularityFunction(x, 2, -1)
assert b.applied_loads == [(-3, 0, -2, None), (4, 2, -1, None)]
try:
b.remove_load(1, 2, -1)
# As load of this magnitude was never applied at
# this position, method should return a ValueError.
except ValueError:
assert True
else:
assert False
b.remove_load(-3, 0, -2)
b.remove_load(4, 2, -1)
assert b.load == 0
assert b.applied_loads == []
def test_apply_support():
E = Symbol('E')
I = Symbol('I')
b = Beam(4, E, I)
b.apply_support(0, "cantilever")
b.apply_load(20, 4, -1)
M_0, R_0 = symbols('M_0, R_0')
b.solve_for_reaction_loads(R_0, M_0)
assert simplify(b.slope()) == simplify((80*SingularityFunction(x, 0, 1) - 10*SingularityFunction(x, 0, 2)
+ 10*SingularityFunction(x, 4, 2))/(E*I))
assert simplify(b.deflection()) == simplify((40*SingularityFunction(x, 0, 2) - 10*SingularityFunction(x, 0, 3)/3
+ 10*SingularityFunction(x, 4, 3)/3)/(E*I))
b = Beam(30, E, I)
b.apply_support(10, "pin")
b.apply_support(30, "roller")
b.apply_load(-8, 0, -1)
b.apply_load(120, 30, -2)
R_10, R_30 = symbols('R_10, R_30')
b.solve_for_reaction_loads(R_10, R_30)
assert b.slope() == (-4*SingularityFunction(x, 0, 2) + 3*SingularityFunction(x, 10, 2)
+ 120*SingularityFunction(x, 30, 1) + SingularityFunction(x, 30, 2) + Rational(4000, 3))/(E*I)
assert b.deflection() == (x*Rational(4000, 3) - 4*SingularityFunction(x, 0, 3)/3 + SingularityFunction(x, 10, 3)
+ 60*SingularityFunction(x, 30, 2) + SingularityFunction(x, 30, 3)/3 - 12000)/(E*I)
P = Symbol('P', positive=True)
L = Symbol('L', positive=True)
b = Beam(L, E, I)
b.apply_support(0, type='fixed')
b.apply_support(L, type='fixed')
b.apply_load(-P, L/2, -1)
R_0, R_L, M_0, M_L = symbols('R_0, R_L, M_0, M_L')
b.solve_for_reaction_loads(R_0, R_L, M_0, M_L)
assert b.reaction_loads == {R_0: P/2, R_L: P/2, M_0: -L*P/8, M_L: L*P/8}
def test_max_shear_force():
E = Symbol('E')
I = Symbol('I')
b = Beam(3, E, I)
R, M = symbols('R, M')
b.apply_load(R, 0, -1)
b.apply_load(M, 0, -2)
b.apply_load(2, 3, -1)
b.apply_load(4, 2, -1)
b.apply_load(2, 2, 0, end=3)
b.solve_for_reaction_loads(R, M)
assert b.max_shear_force() == (Interval(0, 2), 8)
l = symbols('l', positive=True)
P = Symbol('P')
b = Beam(l, E, I)
R1, R2 = symbols('R1, R2')
b.apply_load(R1, 0, -1)
b.apply_load(R2, l, -1)
b.apply_load(P, 0, 0, end=l)
b.solve_for_reaction_loads(R1, R2)
assert b.max_shear_force() == (0, l*Abs(P)/2)
def test_max_bmoment():
E = Symbol('E')
I = Symbol('I')
l, P = symbols('l, P', positive=True)
b = Beam(l, E, I)
R1, R2 = symbols('R1, R2')
b.apply_load(R1, 0, -1)
b.apply_load(R2, l, -1)
b.apply_load(P, l/2, -1)
b.solve_for_reaction_loads(R1, R2)
b.reaction_loads
assert b.max_bmoment() == (l/2, P*l/4)
b = Beam(l, E, I)
R1, R2 = symbols('R1, R2')
b.apply_load(R1, 0, -1)
b.apply_load(R2, l, -1)
b.apply_load(P, 0, 0, end=l)
b.solve_for_reaction_loads(R1, R2)
assert b.max_bmoment() == (l/2, P*l**2/8)
def test_max_deflection():
E, I, l, F = symbols('E, I, l, F', positive=True)
b = Beam(l, E, I)
b.bc_deflection = [(0, 0),(l, 0)]
b.bc_slope = [(0, 0),(l, 0)]
b.apply_load(F/2, 0, -1)
b.apply_load(-F*l/8, 0, -2)
b.apply_load(F/2, l, -1)
b.apply_load(F*l/8, l, -2)
b.apply_load(-F, l/2, -1)
assert b.max_deflection() == (l/2, F*l**3/(192*E*I))
def test_Beam3D():
l, E, G, I, A = symbols('l, E, G, I, A')
R1, R2, R3, R4 = symbols('R1, R2, R3, R4')
b = Beam3D(l, E, G, I, A)
m, q = symbols('m, q')
b.apply_load(q, 0, 0, dir="y")
b.apply_moment_load(m, 0, 0, dir="z")
b.bc_slope = [(0, [0, 0, 0]), (l, [0, 0, 0])]
b.bc_deflection = [(0, [0, 0, 0]), (l, [0, 0, 0])]
b.solve_slope_deflection()
assert b.polar_moment() == 2*I
assert b.shear_force() == [0, -q*x, 0]
assert b.shear_stress() == [0, -q*x/A, 0]
assert b.axial_stress() == 0
assert b.bending_moment() == [0, 0, -m*x + q*x**2/2]
expected_deflection = (x*(A*G*q*x**3/4 + A*G*x**2*(-l*(A*G*l*(l*q - 2*m) +
12*E*I*q)/(A*G*l**2 + 12*E*I)/2 - m) + 3*E*I*l*(A*G*l*(l*q - 2*m) +
12*E*I*q)/(A*G*l**2 + 12*E*I) + x*(-A*G*l**2*q/2 +
3*A*G*l**2*(A*G*l*(l*q - 2*m) + 12*E*I*q)/(A*G*l**2 + 12*E*I)/4 +
A*G*l*m*Rational(3, 2) - 3*E*I*q))/(6*A*E*G*I))
dx, dy, dz = b.deflection()
assert dx == dz == 0
assert simplify(dy - expected_deflection) == 0
b2 = Beam3D(30, E, G, I, A, x)
b2.apply_load(50, start=0, order=0, dir="y")
b2.bc_deflection = [(0, [0, 0, 0]), (30, [0, 0, 0])]
b2.apply_load(R1, start=0, order=-1, dir="y")
b2.apply_load(R2, start=30, order=-1, dir="y")
b2.solve_for_reaction_loads(R1, R2)
assert b2.reaction_loads == {R1: -750, R2: -750}
b2.solve_slope_deflection()
assert b2.slope() == [0, 0, 25*x**3/(3*E*I) - 375*x**2/(E*I) + 3750*x/(E*I)]
expected_deflection = 25*x**4/(12*E*I) - 125*x**3/(E*I) + 1875*x**2/(E*I) - \
25*x**2/(A*G) + 750*x/(A*G)
dx, dy, dz = b2.deflection()
assert dx == dz == 0
assert dy == expected_deflection
# Test for solve_for_reaction_loads
b3 = Beam3D(30, E, G, I, A, x)
b3.apply_load(8, start=0, order=0, dir="y")
b3.apply_load(9*x, start=0, order=0, dir="z")
b3.apply_load(R1, start=0, order=-1, dir="y")
b3.apply_load(R2, start=30, order=-1, dir="y")
b3.apply_load(R3, start=0, order=-1, dir="z")
b3.apply_load(R4, start=30, order=-1, dir="z")
b3.solve_for_reaction_loads(R1, R2, R3, R4)
assert b3.reaction_loads == {R1: -120, R2: -120, R3: -1350, R4: -2700}
def test_polar_moment_Beam3D():
l, E, G, A, I1, I2 = symbols('l, E, G, A, I1, I2')
I = [I1, I2]
b = Beam3D(l, E, G, I, A)
assert b.polar_moment() == I1 + I2
def test_parabolic_loads():
E, I, L = symbols('E, I, L', positive=True, real=True)
R, M, P = symbols('R, M, P', real=True)
# cantilever beam fixed at x=0 and parabolic distributed loading across
# length of beam
beam = Beam(L, E, I)
beam.bc_deflection.append((0, 0))
beam.bc_slope.append((0, 0))
beam.apply_load(R, 0, -1)
beam.apply_load(M, 0, -2)
# parabolic load
beam.apply_load(1, 0, 2)
beam.solve_for_reaction_loads(R, M)
assert beam.reaction_loads[R] == -L**3/3
# cantilever beam fixed at x=0 and parabolic distributed loading across
# first half of beam
beam = Beam(2*L, E, I)
beam.bc_deflection.append((0, 0))
beam.bc_slope.append((0, 0))
beam.apply_load(R, 0, -1)
beam.apply_load(M, 0, -2)
# parabolic load from x=0 to x=L
beam.apply_load(1, 0, 2, end=L)
beam.solve_for_reaction_loads(R, M)
# result should be the same as the prior example
assert beam.reaction_loads[R] == -L**3/3
# check constant load
beam = Beam(2*L, E, I)
beam.apply_load(P, 0, 0, end=L)
loading = beam.load.xreplace({L: 10, E: 20, I: 30, P: 40})
assert loading.xreplace({x: 5}) == 40
assert loading.xreplace({x: 15}) == 0
# check ramp load
beam = Beam(2*L, E, I)
beam.apply_load(P, 0, 1, end=L)
assert beam.load == (P*SingularityFunction(x, 0, 1) -
P*SingularityFunction(x, L, 1) -
P*L*SingularityFunction(x, L, 0))
# check higher order load: x**8 load from x=0 to x=L
beam = Beam(2*L, E, I)
beam.apply_load(P, 0, 8, end=L)
loading = beam.load.xreplace({L: 10, E: 20, I: 30, P: 40})
assert loading.xreplace({x: 5}) == 40*5**8
assert loading.xreplace({x: 15}) == 0
def test_cross_section():
I = Symbol('I')
l = Symbol('l')
E = Symbol('E')
C3, C4 = symbols('C3, C4')
a, c, g, h, r, n = symbols('a, c, g, h, r, n')
# test for second_moment and cross_section setter
b0 = Beam(l, E, I)
assert b0.second_moment == I
assert b0.cross_section == None
b0.cross_section = Circle((0, 0), 5)
assert b0.second_moment == pi*Rational(625, 4)
assert b0.cross_section == Circle((0, 0), 5)
b0.second_moment = 2*n - 6
assert b0.second_moment == 2*n-6
assert b0.cross_section == None
with raises(ValueError):
b0.second_moment = Circle((0, 0), 5)
# beam with a circular cross-section
b1 = Beam(50, E, Circle((0, 0), r))
assert b1.cross_section == Circle((0, 0), r)
assert b1.second_moment == pi*r*Abs(r)**3/4
b1.apply_load(-10, 0, -1)
b1.apply_load(R1, 5, -1)
b1.apply_load(R2, 50, -1)
b1.apply_load(90, 45, -2)
b1.solve_for_reaction_loads(R1, R2)
assert b1.load == (-10*SingularityFunction(x, 0, -1) + 82*SingularityFunction(x, 5, -1)/S(9)
+ 90*SingularityFunction(x, 45, -2) + 8*SingularityFunction(x, 50, -1)/9)
assert b1.bending_moment() == (10*SingularityFunction(x, 0, 1) - 82*SingularityFunction(x, 5, 1)/9
- 90*SingularityFunction(x, 45, 0) - 8*SingularityFunction(x, 50, 1)/9)
q = (-5*SingularityFunction(x, 0, 2) + 41*SingularityFunction(x, 5, 2)/S(9)
+ 90*SingularityFunction(x, 45, 1) + 4*SingularityFunction(x, 50, 2)/S(9))/(pi*E*r*Abs(r)**3)
assert b1.slope() == C3 + 4*q
q = (-5*SingularityFunction(x, 0, 3)/3 + 41*SingularityFunction(x, 5, 3)/27 + 45*SingularityFunction(x, 45, 2)
+ 4*SingularityFunction(x, 50, 3)/27)/(pi*E*r*Abs(r)**3)
assert b1.deflection() == C3*x + C4 + 4*q
# beam with a recatangular cross-section
b2 = Beam(20, E, Polygon((0, 0), (a, 0), (a, c), (0, c)))
assert b2.cross_section == Polygon((0, 0), (a, 0), (a, c), (0, c))
assert b2.second_moment == a*c**3/12
# beam with a triangular cross-section
b3 = Beam(15, E, Triangle((0, 0), (g, 0), (g/2, h)))
assert b3.cross_section == Triangle(Point2D(0, 0), Point2D(g, 0), Point2D(g/2, h))
assert b3.second_moment == g*h**3/36
# composite beam
b = b2.join(b3, "fixed")
b.apply_load(-30, 0, -1)
b.apply_load(65, 0, -2)
b.apply_load(40, 0, -1)
b.bc_slope = [(0, 0)]
b.bc_deflection = [(0, 0)]
assert b.second_moment == Piecewise((a*c**3/12, x <= 20), (g*h**3/36, x <= 35))
assert b.cross_section == None
assert b.length == 35
assert b.slope().subs(x, 7) == 8400/(E*a*c**3)
assert b.slope().subs(x, 25) == 52200/(E*g*h**3) + 39600/(E*a*c**3)
assert b.deflection().subs(x, 30) == -537000/(E*g*h**3) - 712000/(E*a*c**3)
def test_max_shear_force_Beam3D():
x = symbols('x')
b = Beam3D(20, 40, 21, 100, 25)
b.apply_load(15, start=0, order=0, dir="z")
b.apply_load(12*x, start=0, order=0, dir="y")
b.bc_deflection = [(0, [0, 0, 0]), (20, [0, 0, 0])]
assert b.max_shear_force() == [(0, 0), (20, 2400), (20, 300)]
def test_max_bending_moment_Beam3D():
x = symbols('x')
b = Beam3D(20, 40, 21, 100, 25)
b.apply_load(15, start=0, order=0, dir="z")
b.apply_load(12*x, start=0, order=0, dir="y")
b.bc_deflection = [(0, [0, 0, 0]), (20, [0, 0, 0])]
assert b.max_bmoment() == [(0, 0), (20, 3000), (20, 16000)]
def test_max_deflection_Beam3D():
x = symbols('x')
b = Beam3D(20, 40, 21, 100, 25)
b.apply_load(15, start=0, order=0, dir="z")
b.apply_load(12*x, start=0, order=0, dir="y")
b.bc_deflection = [(0, [0, 0, 0]), (20, [0, 0, 0])]
b.solve_slope_deflection()
c = sympify("495/14")
p = sympify("-10 + 10*sqrt(10793)/43")
q = sympify("(10 - 10*sqrt(10793)/43)**3/160 - 20/7 + (10 - 10*sqrt(10793)/43)**4/6400 + 20*sqrt(10793)/301 + 27*(10 - 10*sqrt(10793)/43)**2/560")
assert b.max_deflection() == [(0, 0), (10, c), (p, q)]