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residual_force

ResidualForce

Bases: MessagePassing

Computes the per-node residual force from axial member forces and applied loads.

Source code in src/torch_structure/message_passing/residual_force.py 
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class ResidualForce(MessagePassing):  # only works for undirected graphs!
    """Computes the per-node residual force from axial member forces and applied loads."""

    def __init__(self):
        super().__init__(aggr="add")

    def forward(self, x, force, edge_index, load):
        """Sum each node's incident axial member forces and add the applied load.

        Args:
            x (torch.Tensor [N, D]): node coordinates.
            force (torch.Tensor [E]): axial force magnitude of each member.
            edge_index (torch.Tensor [2, E]): edge connectivity (undirected).
            load (torch.Tensor [N, D]): externally applied nodal loads.

        Returns:
            torch.Tensor [N, D]: the residual force at each node.
        """
        force = force.view(-1)
        out = self.propagate(edge_index, x=x, force=force)
        out = out + load
        return out

    def message(self, x_i, x_j, force):
        """Compute the force vector a member exerts on its target (center) node, along its direction."""
        vector = x_j - x_i
        vector = vector / torch.norm(vector, dim=1).unsqueeze(1) * force.unsqueeze(1)
        return vector

forward(x, force, edge_index, load)

Sum each node's incident axial member forces and add the applied load.

Parameters:

Name Type Description Default
x Tensor[N, D]

node coordinates.

 required
force Tensor[E]

axial force magnitude of each member.

 required
edge_index Tensor[2, E]

edge connectivity (undirected).

 required
load Tensor[N, D]

externally applied nodal loads.

 required

Returns:

Type Description

torch.Tensor [N, D]: the residual force at each node.
Source code in src/torch_structure/message_passing/residual_force.py 
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def forward(self, x, force, edge_index, load):
    """Sum each node's incident axial member forces and add the applied load.

    Args:
        x (torch.Tensor [N, D]): node coordinates.
        force (torch.Tensor [E]): axial force magnitude of each member.
        edge_index (torch.Tensor [2, E]): edge connectivity (undirected).
        load (torch.Tensor [N, D]): externally applied nodal loads.

    Returns:
        torch.Tensor [N, D]: the residual force at each node.
    """
    force = force.view(-1)
    out = self.propagate(edge_index, x=x, force=force)
    out = out + load
    return out

message(x_i, x_j, force)

Compute the force vector a member exerts on its target (center) node, along its direction.

Source code in src/torch_structure/message_passing/residual_force.py 
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def message(self, x_i, x_j, force):
    """Compute the force vector a member exerts on its target (center) node, along its direction."""
    vector = x_j - x_i
    vector = vector / torch.norm(vector, dim=1).unsqueeze(1) * force.unsqueeze(1)
    return vector