This library is used to create representations of trusses and can be used for truss optimisation

To initialize a 2d truss object, call the trust class

truss = Truss(2)

You can pass in 3 to create a 3d truss object.

To create the truss, you must first define the nodes of the truss. this can be done by calling the add_node() method. Each node must be passed a location for the node. The node can also be passed constrained conidtions and forces acting on the node. for example

truss = truss.add_node([0,1], [false, true], [0,100])

creates a node at location x = 0 and y = 1, which is constrained in the x direction but free in the y direction, which has a force acting 100 units in the positive y direction.

To add a beam to the truss call the add_beam() method. for example:

truss = truss.add_beam(idx1, idx2, youngs, area, maxstress)

adds a beam to the truss object, with the start of the beam at the node at the index specified by idx1 in the truss object and the end specified by idx2. youngs is Young's modulus for the beam, area is the cross-sectional area of the beam, maxstress is the designed max stress of the beam.

For large trusses, it is recomended to set up both the nodes and the beams in for loops. see the examples for reference.

Now we can enter our loop of optimization. We first call the build method to build the s and k matrixes. From there, call the solve method to solve the truss and vuolla! the truss has been solved!

truss = truss.build()
truss = truss.solve()

The matrix is currently inverted using the built-in MATLAB \ operator, but that can be easily changed.

To find the total weight of the truss, call the calc_weight method truss = truss.calc_weight()

finally to do a basic optimization, call the optimize method truss=truss.optimize()

This does the basic new_area = old_area * (stress / max_stress) On each beam to optimize the truss

Bellow is an example from the research paper found in trusses/2d/paper2d

YOUNGS = 10000;
MAXSTRESS = 65;

beam_nodes = [
    5, 3;
    3, 1;
    6, 4;
    4, 2;
    4, 3;
    2, 1;
    5, 4;
    6, 3;
    3, 2;
    4, 1;
];

areas = rand(size(beam_nodes)) * 10;


% 2 is the number of dimentions
truss = Truss(2);


% this is the loads for case 1
% build the nodes
for i = 3:-1:1
    if i == 1
        constrained = true;
        forces = [0,0,0];
    else
        constrained = false;
        forces = [0,-100,0];
    end
    % coordes are in inches
    truss = truss.add_node([(i-1) * 360,360,0], [constrained, constrained, false]);
    truss = truss.add_node([(i-1) * 360,0,0], [constrained, constrained, false], forces);
end

% adds the beam to the structure
for i = 1:size(beam_nodes)
    node1 = beam_nodes(i,1);
    node2 = beam_nodes(i,2);
    truss = truss.add_beam(node1, node2, YOUNGS, areas(i), MAXSTRESS);
end

truss = basic_optimize(truss, 50)

Note that the basic_optimize function calls the truss's optimize method 50 times

To visualize the trusses, call the plot method once the truss is built.

truss.plot()

Or to see displacements, call the plot_dis method once the truss is solved

truss.plot_dis()