86 lines
2.6 KiB
Python
86 lines
2.6 KiB
Python
from pytest import raises
|
|
|
|
from sympy import symbols
|
|
from sympy.physics.mechanics import (RigidBody, Particle, ReferenceFrame, Point,
|
|
outer, dynamicsymbols, Force, Torque)
|
|
from sympy.physics.mechanics.loads import gravity, _parse_load
|
|
|
|
|
|
def test_force_default():
|
|
N = ReferenceFrame('N')
|
|
Po = Point('Po')
|
|
f1 = Force(Po, N.x)
|
|
assert f1.point == Po
|
|
assert f1.force == N.x
|
|
assert f1.__repr__() == 'Force(point=Po, force=N.x)'
|
|
# Test tuple behaviour
|
|
assert isinstance(f1, tuple)
|
|
assert f1[0] == Po
|
|
assert f1[1] == N.x
|
|
assert f1 == (Po, N.x)
|
|
assert f1 != (N.x, Po)
|
|
assert f1 != (Po, N.x + N.y)
|
|
assert f1 != (Point('Co'), N.x)
|
|
# Test body as input
|
|
P = Particle('P', Po)
|
|
f2 = Force(P, N.x)
|
|
assert f1 == f2
|
|
|
|
|
|
def test_torque_default():
|
|
N = ReferenceFrame('N')
|
|
f1 = Torque(N, N.x)
|
|
assert f1.frame == N
|
|
assert f1.torque == N.x
|
|
assert f1.__repr__() == 'Torque(frame=N, torque=N.x)'
|
|
# Test tuple behaviour
|
|
assert isinstance(f1, tuple)
|
|
assert f1[0] == N
|
|
assert f1[1] == N.x
|
|
assert f1 == (N, N.x)
|
|
assert f1 != (N.x, N)
|
|
assert f1 != (N, N.x + N.y)
|
|
assert f1 != (ReferenceFrame('A'), N.x)
|
|
# Test body as input
|
|
rb = RigidBody('P', frame=N)
|
|
f2 = Torque(rb, N.x)
|
|
assert f1 == f2
|
|
|
|
|
|
def test_gravity():
|
|
N = ReferenceFrame('N')
|
|
m, M, g = symbols('m M g')
|
|
F1, F2 = dynamicsymbols('F1 F2')
|
|
po = Point('po')
|
|
pa = Particle('pa', po, m)
|
|
A = ReferenceFrame('A')
|
|
P = Point('P')
|
|
I = outer(A.x, A.x)
|
|
B = RigidBody('B', P, A, M, (I, P))
|
|
forceList = [(po, F1), (P, F2)]
|
|
forceList.extend(gravity(g * N.y, pa, B))
|
|
l = [(po, F1), (P, F2), (po, g * m * N.y), (P, g * M * N.y)]
|
|
|
|
for i in range(len(l)):
|
|
for j in range(len(l[i])):
|
|
assert forceList[i][j] == l[i][j]
|
|
|
|
|
|
def test_parse_loads():
|
|
N = ReferenceFrame('N')
|
|
po = Point('po')
|
|
assert _parse_load(Force(po, N.z)) == (po, N.z)
|
|
assert _parse_load(Torque(N, N.x)) == (N, N.x)
|
|
f1 = _parse_load((po, N.x)) # Test whether a force is recognized
|
|
assert isinstance(f1, Force)
|
|
assert f1 == Force(po, N.x)
|
|
t1 = _parse_load((N, N.y)) # Test whether a torque is recognized
|
|
assert isinstance(t1, Torque)
|
|
assert t1 == Torque(N, N.y)
|
|
# Bodies should be undetermined (even in case of a Particle)
|
|
raises(ValueError, lambda: _parse_load((Particle('pa', po), N.x)))
|
|
raises(ValueError, lambda: _parse_load((RigidBody('pa', po, N), N.x)))
|
|
# Invalid tuple length
|
|
raises(ValueError, lambda: _parse_load((po, N.x, po, N.x)))
|
|
# Invalid type
|
|
raises(TypeError, lambda: _parse_load([po, N.x]))
|