class Constrainer:
"""
A class that represents a constrainer for fixing degrees of freedom in a structural analysis.
Attributes:
cons_dofs (list): A list of constrained degrees of freedom.
cons_vals (list): A list of corresponding constraint values.
Methods:
fix_dof: Fixes a degree of freedom at a specific value.
fix_node: Fixes all degrees of freedom of a node.
full_disp: Combines the displacements of free and constrained degrees of freedom.
constrain: Applies the constraints to the stiffness matrix and load vector.
support_reactions: Calculates the support reactions based on the constrained displacements.
"""
def __init__(self):
"""
Initializes a new instance of the Constrainer class.
Attributes:
cons_dofs (list): A list of constrained degrees of freedom.
cons_vals (list): A list of corresponding constraint values.
"""
self.cons_dofs = []
self.cons_vals = []
def fix_dof (self, node, dof, value = 0):
"""
Fixes a degree of freedom at a specific value.
Args:
node (Node): The node object.
dof (int): The index of the degree of freedom to fix.
value (float, optional): The value to fix the degree of freedom at. Defaults to 0.
"""
self.cons_dofs.append(node.dofs[dof])
assert value == 0, "Only zero values are supported for now."
self.cons_vals.append(value)
def fix_node (self, node):
"""
Fixes all degrees of freedom of a node.
Args:
node (Node): The node object.
"""
for dof in [0,1,2]:
self.fix_dof (node, dof)
def full_disp (self,u_free):
"""
Combines the displacements of free and constrained degrees of freedom.
Args:
u_free (numpy.ndarray): The displacements of the free degrees of freedom.
Returns:
numpy.ndarray: The combined displacements of all degrees of freedom.
"""
u_full = np.zeros(len(self.free_dofs) + len(self.cons_dofs))
u_full[self.free_dofs] = u_free
u_full[self.cons_dofs] = self.cons_vals
return u_full
def constrain (self, k, f):
"""
Applies the constraints to the stiffness matrix and load vector.
Args:
k (numpy.ndarray): The stiffness matrix.
f (numpy.ndarray): The load vector.
Returns:
tuple: A tuple containing the stiffness matrix corresponding to free dofs and the corresponding load vector.
"""
self.free_dofs = [i for i in range(len(f)) if i not in self.cons_dofs]
Kff #= k[np.ix_(YOUR CODE HERE)]
Ff # YOUR CODE HERE
return Kff, Ff
def support_reactions (self,k,u_free,f):
"""
Calculates the support reactions based on the constrained displacements.
Args:
k (numpy.ndarray): The stiffness matrix.
u_free (numpy.ndarray): The displacements of the free degrees of freedom.
f (numpy.ndarray): The load vector.
Returns:
numpy.ndarray: The support reactions.
"""
#YOUR CODE HERE
return #YOUR CODE HERE
def __str__(self):
"""
Returns a string representation of the Constrainer object.
Returns:
str: A string representation of the Constrainer object.
"""
return f"This constrainer has constrained the degrees of freedom: {self.cons_dofs} with corresponding constrained values: {self.cons_vals})"
