%% Compute ABD Matrix A = zeros(3,3); B = zeros(3,3); D = zeros(3,3); for k = 1:num_plies theta_k = theta(k) * pi/180; m = cos(theta_k); n = sin(theta_k); % Transformation matrix T = [m^2, n^2, 2 m n; n^2, m^2, -2 m n; -m n, m n, m^2-n^2]; % Q_bar = T * Q * T_inv Q = [Q11, Q12, 0; Q12, Q22, 0; 0, 0, Q66]; Q_bar = T * Q * T'; % Integrate through thickness A = A + Q_bar * (z(k+1)-z(k)); B = B + Q_bar * 0.5 * (z(k+1)^2 - z(k)^2); D = D + Q_bar * (1/3) * (z(k+1)^3 - z(k)^3); end % For symmetric laminate, B should be zero (numerically small) B = zeros(3,3); % enforce symmetry
[ \frac{\partial^4 w}{\partial x^2 \partial y^2} \approx \frac{ w_{i-1,j-1} - 2w_{i-1,j} + w_{i-1,j+1} - 2w_{i,j-1} + 4w_{i,j} - 2w_{i,j+1} + w_{i+1,j-1} - 2w_{i+1,j} + w_{i+1,j+1} }{\Delta x^2 \Delta y^2} ] Composite Plate Bending Analysis With Matlab Code
boundary_nodes = []; for i = 1:Nx for j = [1, Ny] boundary_nodes = [boundary_nodes, idx(i,j)]; end end for j = 2:Ny-1 boundary_nodes = [boundary_nodes, idx(1,j), idx(Nx,j)]; end boundary_nodes = unique(boundary_nodes); %% Compute ABD Matrix A = zeros(3,3); B
% Central difference coefficients c1 = D(1,1)/dx^4; c2 = (2*(D(1,2)+2 D(3,3)))/(dx^2 dy^2); c3 = D(2,2)/dy^4; B = zeros(3
%% Finite Difference Grid Nx = 41; Ny = 25; % odd numbers to include center dx = a/(Nx-1); dy = b/(Ny-1); x = linspace(0, a, Nx); y = linspace(0, b, Ny);