How do I make a 3D model using Matlab Patch function?

Hello,

So I have a problem using patch function. So bascally, I am trying to code for a truss pratt bridge, whereby I have all my nodes. Yet, I want each member to look 3D, as in to have some thickness and dimension rather than being just a straight line which is what I have right now. Any help? Also, I need to determine the loading using DSM, if there is any link you know helpful please let me know, i need to set each member to be coloured regarding to the force it experiences when a truck is driving through.

Here is my code !

Height=8.66;

Nodes_f= [ 0 6 0; % Node 1

10 6 0; % Node 2

20 6 0; % Node 3

30 6 0; % Node 4

40 6 0; % Node 5

50 6 0; % Node 6

5 6 Height; % Node 7

15 6 Height; % Node 8

25 6 Height; % Node 9

35 6 Height; % Node 10

45 6 Height; % Node 11

5 6 0; % Node 12

10 6 Height; % Node 13

15 6 0; % Node 14

20 6 Height; % Node 15

25 6 0; % Node 16

30 6 Height; % Node 17

35 6 0; % Node 18

40 6 Height; % Node 19

45 6 0; % Node 20

];

faces=[ 1 2; 1 7; 7 2; 7 8; 2 8; 2 3; 8 3; 8 9; 3 4;

3 9; 9 4; 4 5; 9 10; 4 10; 10 5; 5 11; 10 11;

5 6; 11 6; 12 7; 2 13; 8 14; 3 15; 9 16; 4 17;

10 18; 5 19; 11 20];

c = [0.8500 0.3250 0.0980]

patch('Faces',faces,'Vertices',Nodes_f,'Edgecolor',c,'LineWidth',2);

view(3)

colorbar

hold on;

Thank you !

Answer 1

[Jaynik]

Hi Karina,

According to me, there is no direct function to plot the bridge in 3D with some thickness and dimension. You will have to custom code for plotting in 3D. Here is a sample code which uses rectangular beams to construct the bridge:

beamWidth = 2; % Width of the beam in the same units as your nodes
beamThickness = 0.2; % Thickness of the beam

figure;
hold on;
for i = 1:size(faces, 1)
    startNode = Nodes_f(faces(i, 1), :);
    endNode = Nodes_f(faces(i, 2), :);
    draw3DBeam(startNode, endNode, beamWidth, beamThickness, c);
end
view(3);
axis equal;
grid on;

function draw3DBeam(startNode, endNode, width, thickness, color)
    % Direction vectors
    dirVector = endNode - startNode;
    dirVector = dirVector / norm(dirVector); % Normalize
    upVector = [0, 0, 1]; % Up vector

    % Perpendicular vector to the direction and up vector
    perpVector = cross(dirVector, upVector);
    perpVector = perpVector / norm(perpVector); % Normalize

    % Four corners of the beam
    corner1 = startNode + width/2 * perpVector + thickness/2 * upVector;
    corner2 = startNode - width/2 * perpVector + thickness/2 * upVector;
    corner3 = startNode - width/2 * perpVector - thickness/2 * upVector;
    corner4 = startNode + width/2 * perpVector - thickness/2 * upVector;

    % End nodes of the beam
    corner5 = endNode + width/2 * perpVector + thickness/2 * upVector;
    corner6 = endNode - width/2 * perpVector + thickness/2 * upVector;
    corner7 = endNode - width/2 * perpVector - thickness/2 * upVector;
    corner8 = endNode + width/2 * perpVector - thickness/2 * upVector;

    % Vertices and faces for the patch
    vertices = [corner1; corner2; corner3; corner4; corner5; corner6; corner7; corner8];
    faces = [1 2 3 4; 5 6 7 8; 1 5 8 4; 2 6 7 3; 1 5 6 2; 4 8 7 3];
    patch('Faces',faces,'Vertices',vertices,'FaceColor',color, 'EdgeColor', 'none');
end

You will need to change the implementation of draw3DBeam based on your specific requirements.

To perform further analysis for the truss bridge, you can try exploring these from File Exchange:

• https://www.mathworks.com/matlabcentral/fileexchange/134451-interactive-truss-solver
• https://www.mathworks.com/matlabcentral/fileexchange/127828-3d-truss-analysis
• https://www.mathworks.com/matlabcentral/fileexchange/6832-3d-truss-analysis-user-interface-in-fem
• https://www.mathworks.com/matlabcentral/fileexchange/68337-finite-element-analysis-fea-of-2d-and-3d-truss-structure

Hope this helps!