Composite Plate Bending Analysis - With Matlab Code

% Contribution to bending stiffness D zk = z_coords(k+1); zk_1 = z_coords(k); D = D + (1/3) * Q_bar * (zk^3 - zk_1^3); end

%% 4. Mesh Generation nx = Nx_elem + 1; ny = Ny_elem + 1; x_nodes = linspace(0, a, nx); y_nodes = linspace(0, b, ny); [X, Y] = meshgrid(x_nodes, y_nodes);

% Complete set of 12 basis functions: P = [1, xi, eta, xi^2, xi eta, eta^2, xi^3, xi^2 eta, xi eta^2, eta^3, xi^3 eta, xi eta^3]; % Evaluate at each node (xi=-1,1; eta=-1,1) to get interpolation matrix, then invert. % For brevity, we implement direct B matrix in compute_B_matrix. % This function is kept as placeholder. Nw = [(1-xi) (1-eta)/4, (1+xi) (1-eta)/4, (1+xi) (1+eta)/4, (1-xi)*(1+eta)/4]; dN = zeros(2,4); end Composite Plate Bending Analysis With Matlab Code

function [Nw, dN] = shape_functions(xi, eta) % Shape functions and derivatives for w (12-term polynomial) % xi, eta in [-1,1] for master element (size 2a x 2b) % Returns Nw (1x4) for nodal w, dN (2x4) for slopes? Actually we need 12 DOF. % Here simplified: we return shape functions for w only. % For full [B] matrix, we need derivatives of w wrt x,y.

% In practice, you can use the MITC4 element for plates. % Here we output a dummy B and detJ for completeness. % Contribution to bending stiffness D zk =

% Shape functions for w and slopes (σ = -dw/dx, τ = dw/dy) % Node 1 (xi=-1, eta=-1) N(1) = 1/8 * (1-xi) (1-eta) ( (1+xi)^2*(1+eta)^2 - (1+xi)*(1+eta) - (1+xi)^2 - (1+eta)^2 + 2 ); % Similar for others – too lengthy. Instead, we use a simplified approach: % For demonstration and educational clarity, we assume a reduced integration % and approximate B using bilinear w + constant slopes. Full derivation is long.

%% 9. Plot Deflection Surface figure; surf(X, Y, W'); xlabel('x (m)'); ylabel('y (m)'); zlabel('Deflection (m)'); title('Composite Plate Bending Deflection'); colormap(jet); colorbar; view(120,30); grid on; % This function is kept as placeholder

% Find center deflection center_x = floor(nx/2)+1; center_y = floor(ny/2)+1; w_center_FEM = W(center_x, center_y);