How can I fix this error?

%Compute stresses through the thickness of a laminate
%Read in number of layers
num_layers=input('Enter the number of layers: ');
%Read in material properties
E_L=input('Enter longitudinal modulus E_L [GPa]: ');
E_T=input('Enter transverse modulus E_T [GPa]: ');
G_LT=input('Enter shear modulus G_LT [GPa]: ');
v_LT=input('Enter Poisson"s Ratio v_LT: ');
thickness=input('Enter lamina thickness: ');
%Compute Q
Q=calculate_Q(E_L,E_T,G_LT,v_LT);
%Givin mid-plane strains and curvatures
%Format: [εx,εy,γxy, κx, κy]
epsilon_x=input('Enter εx: ');
epsilon_y=input('Enter εy: ');
gamma_xy=input('Enter γxy: ');
kappa_x=input('Enter κx: ');
kappa_y=input('Enter κy: ');
mid_plane_data=[epsilon_x, epsilon_y, gamma_xy, kappa_x, kappa_y];
%Compute stresses for each layer
top_bottom_stresses = cell(num_layers, 2);
for i = 1:size(mid_plane_data, 1)
    data = mid_plane_data(i,:);
    strain = data(1:3)';
    curvature = data(4:5)';
    
    % Compute S matrix
    S = (Q)^-1;
    
    % Compute strain due to curvature
    strain_due_to_curvature = S .* curvature .* thickness / 2;
    
    % Compute total strain at top and bottom
    total_strain_top = strain + strain_due_to_curvature;
    total_strain_bottom = strain - strain_due_to_curvature;
    
    % Compute stress at top and bottom
    stress_top = Q .* total_strain_top;
    stress_bottom = Q .* total_strain_bottom;
    top_bottom_stresses{i,1} = stress_top;
    top_bottom_stresses{i,2} = stress_bottom;
end
%Display Results
fprintf('\nStress Values (in MPa):\n');
fprintf('%-10s %-10s %-10s %-10s %-10s %-10s %-10s\n', 'Layer', ...
    'σx_top', 'σy_top', 'τxy_top', 'σx_bottom', 'σy_bottom', ...
    'τxy_bottom');
for i=1:num_layers
    stress_top=top_bottom_stresses{i,1};
    stress_bottom=top_bottom_stresses{i,2};
    fprintf('%-10d %-10.2f %-10.2f %-10.2f %-10.2f %-10.2f %-10.2f\n',i,stress_top(1), ...
        stress_top(2),stress_top(3),stress_bottom(1),stress_bottom(2), ...
        stress_bottom(3));
end
%Plot stress variations through thickness
layer_thickness=0:thickness:(num_layers*thickness);
figure;
hold on;
for i=1:num_layers
    stress_top=top_bottom_stresses{i,1};
    stress_bottom=top_bottom_stresses{i,2};
    plot([stress_top(1),stress_bottom(1)], [layer_thickness(i), layer_thickness(i)],'r-');
    plot([stress_top(2),stress_bottom(2)], [layer_thickness(i), layer_thickness(i)],'b-');
    plot([stress_top(3),stress_bottom(3)], [layer_thickness(i), layer_thickness(i)],'g-');
end
hold off;
xlabel('Stress [MPa]');
ylabel('Thickness [m]');
title('Stress Variation through Thickness of Laminate');
legend('σx', 'σy', 'τxy');
grid on;
%Function to compute Q matrix
function Q=calculate_Q(E_L,E_T,G_LT,v_LT)
Q=zeros(3,3);
Q(1,1)=E_L/(1-v_LT^2);
Q(1,2)=v_LT*E_T/(1-v_LT^2);
Q(2,1)=Q(1,2);
Q(2,2)=E_T/(1-v_LT^2);
Q(3,3)=G_LT;
end

OUTPUT:

Enter the number of layers: 4

Enter longitudinal modulus E_L [GPa]: 38.60

Enter transverse modulus E_T [GPa]: 8.27

Enter shear modulus G_LT [GPa]: 4.14

Enter Poisson"s Ratio v_LT: 0.26

Enter lamina thickness: 0.002

Enter εx: 0.05

Enter εy: 0.00

Enter γxy: 0.00

Enter κx: 0

Enter κy: 0

Arrays have incompatible sizes for this operation.

Error in Project1 (line 40)

strain_due_to_curvature = S .* curvature .* thickness / 2;

Related documentation

[Voss]

Q is a 3x3 matrix, so S is also a 3x3 matrix, but curvature is a 2x1 vector.

Are those the sizes you expect?

You cannot multiply a 3x3 matrix with a 2x1 vector, neither by element-wise multiplication (.*, which is what you are using) nor by matrix multiplication (*).

[Anita Burns]

I missed a variable, it works now! Thank you for pointing that out. However, I am now getting this error,

Index exceeds the number of array elements. Index must not exceed 0.

Error in Project1 (line 63)

fprintf('%-10d %-10.2f %-10.2f %-10.2f %-10.2f %-10.2f %-10.2f\n',i,stress_top(1),stress_top(2),stress_top(3),stress_bottom(1),stress_bottom(2),stress_bottom(3));

[Voss]

You're welcome!

Check the sizes of stress_top and stress_bottom. Looks like at least one of them is empty and it shouldn't be.

If that doesn't help, please share the updated code so I can run it myself and check.

[Anita Burns]

I've got it figured out. Thank you for your help!

[Voss]

You're welcome!