def test_distal_forces(self):
j = FreeJoint('joint')
# Constant loading
j.distal_forces = np.array([2, 3.1, 2.1, 4.3, 2.5, 1.0])
j.calc_external_loading()
assert_array_equal(j.applied_forces[:6], 0)
assert_array_equal(j.applied_forces[6:], j.distal_forces)
assert_array_equal(j.applied_stress, 0)
# Loading function
j.distal_forces = lambda element, t: np.ones(6)
j.calc_external_loading()
assert_array_equal(j.applied_forces[:6], 0)
assert_array_equal(j.applied_forces[6:], 1)
assert_array_equal(j.applied_stress, 0)
def test_distal_forces_cause_acceleration(self):
j = FreeJoint('joint')
b = RigidBody('body', mass=3, inertia=np.diag([7, 7, 7]))
s = System()
s.add_leaf(j)
j.add_leaf(b)
s.setup()
# Constant loading
j.distal_forces = np.array([2, 0, 0, 0, 0, 0])
s.update_kinematics()
s.update_matrices()
s.solve_accelerations()
s.update_kinematics()
assert_array_equal(j.ad, [2. / 3, 0, 0, 0, 0, 0])
