PDE toolbox and load on nodes

I use the PDE Toolbox to analysis a discrete geometry, and I want to put the force vector on a point. But I can't define a point through the syntax "loadedVertex". Is there any other option to define the point? thank you!

Answer 1

[Ravi Kumar]

The function addVertex was introduced in R2019b. You might be running an older version of the MATLAB to get this error.

Regards,

Ravi

[haoran liu]

Thankk you! But when I use the R2019b, I got another error. I can get the VertexID, But I can't put the force on the points.

Answer 2

[Ravi Kumar]

OK, in that case can you number the number of verteices in the model:

>> gm

Do you see the new VertexID in the plot you make?

Regards,

Ravi

[xl z]

Addvertex can not add points on cylindrical surface. Is there a solution to this situation? Thank.

Answer 3

[haoran liu]

Thank you for your answer. Yes, I can see the new VertexID in my model. But I can't solve it with force.

Regards,

haoran

[Ravi Kumar]

Can you share a simplified reproduction code that we can run and see what is going on?

Regards,

Ravi

[haoran liu]

%%
clear
clc
%%
model = createpde('structural','static-solid');

%% import geometry
gm = importGeometry(model,'sta_simplified_400um.stl');
pdegplot(gm, 'VertexLabels', 'on','FaceAlpha', 0.5)
view(30, 30);
title('KGT STA - Faces')
drawnow
%% mesh
hMax = 1.8; % [mm]
hMin = 0.8; % [mm]
tic

mesh = generateMesh(model, 'Hmax', hMax, 'Hmin', hMin);
elapsedTimeMesh = toc;
numOfElems = length(model.Mesh.Elements);
numOfNodes = length(model.Mesh.Nodes);
numOfRacewayNodes = length(findNodes(model.Mesh, 'region', 'Face', 6));
q = meshQuality(model.Mesh);
elemIDs = find(q < 0.3);
pdemesh(model.Mesh,'FaceAlpha',1)
hold on
pdemesh(model.Mesh.Nodes, model.Mesh.Elements(:, elemIDs), 'FaceColor', 'blue', 'EdgeColor', 'blue')
drawnow
%% Material Props
structuralProperties(model, 'Cell', 1, 'YoungsModulus', 200e9, 'PoissonsRatio', 0.3);

%% Boundary Conditions BC
structuralBC(model, 'Face', 15, 'Constraint', 'fixed');
structuralBC(model, 'Face', 2, 'Constraint', 'fixed');

%% load condition

VertexID = addVertex(gm,'Coordinates',[26.253327790164672,9.003630213068949,6.587610172703529]);
%%
pdegplot(gm, 'VertexLabels', 'on','FaceAlpha', 0.5)
view(30, 30);
title('KGT STA - Faces')
drawnow
%%
structuralBoundaryLoad(model,'Vertex',VertexID, 'Force', [10;10;10]);

%% solver
tic
try 
    result = solve(model);
    elapsedTimeSolver = toc;
    disp(['Solver finished in ' num2str(elapsedTimeSolver) ' [s]'])
   catch e
    elapsedTimeSolver = -1;
    disp(['Solver terminated with error "' e.message '", elapsed time: ' num2str(toc) ' [s]'])
   
    return;
end

Thank you! The model is in the attachment.

[Ravi Kumar]

I used the STL in the attachment, sta_simplified_punkt.stl (replace sta_simplified_400um.stl in the reproc code above with sta_simplified_punkt.stl.)

I get the error

Error using pde.DiscreteGeometry/addVertex

Specified point too far from the boundaries.

Error in repro (line 33)

VertexID = addVertex(gm,'Coordinates',[26.253327790164672,9.003630213068949,6.587610172703529]);

This means point is not on the geometric boundary.

Regards,

Ravi

[haoran liu]

Sorry, I have given a false model. The correct model is in the attachment now.

[Ravi Kumar]

Thank. Now I see the issue. You generated mesh before adding vertex. Do all geometry operation before generating mesh. If you move the addVertex to right below importGeometry, you should not get this error.

Regards,

Ravi

[haoran liu]

Thank you! It works

Regards,

haoran