MATLAB code that solves a plannar (2D) truss using the displacement (stiffness) method.
A typical plannar truss is solved using the code. This truss is used as the default example in the code.
Node 1 is pinned and node 9 is free to move only on the x-axis (x-roller).
Nodes 3,5 and 7 are subjected to a force of 50 kN with direction in the negative y-axis.
Node x displacement [m] y displacement [m] x Force [N] y Force [N]
1 0 0 -7.713e-10 7.5e+04
2 0.00025 -0.000303 0 0
3 3.75e-05 -0.0005686 0 -5e+04
4 0.000175 -0.0007237 0 0
5 0.000125 -0.0007914 0 -5e+04
6 7.5e-05 -0.0007237 0 0
7 0.0002125 -0.0005686 0 -5e+04
8 5.514e-19 -0.000303 0 0
9 0.00025 0 0 7.5e+04
Member Area [m^2] E [Pa] Force [N] Strain Stress [Pa]
1 1.00e-02 2.00e+11 -1.061e+05 -5.303e-05 -1.061e+07
2 1.00e-02 2.00e+11 7.5e+04 3.75e-05 7.5e+06
3 1.00e-02 2.00e+11 1.061e+05 5.303e-05 1.061e+07
4 1.00e-02 2.00e+11 -1.5e+05 -7.5e-05 -1.5e+07
5 1.00e-02 2.00e+11 -3.536e+04 -1.768e-05 -3.536e+06
6 1.00e-02 2.00e+11 1.75e+05 8.75e-05 1.75e+07
7 1.00e-02 2.00e+11 3.536e+04 1.768e-05 3.536e+06
8 1.00e-02 2.00e+11 -2e+05 -0.0001 -2e+07
9 1.00e-02 2.00e+11 3.536e+04 1.768e-05 3.536e+06
10 1.00e-02 2.00e+11 1.75e+05 8.75e-05 1.75e+07
11 1.00e-02 2.00e+11 -3.536e+04 -1.768e-05 -3.536e+06
12 1.00e-02 2.00e+11 -1.5e+05 -7.5e-05 -1.5e+07
13 1.00e-02 2.00e+11 1.061e+05 5.303e-05 1.061e+07
14 1.00e-02 2.00e+11 7.5e+04 3.75e-05 7.5e+06
15 1.00e-02 2.00e+11 -1.061e+05 -5.303e-05 -1.061e+07
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