%----------------------------------------------------------------
% PURPOSE
%	Analysis of a plate.
% unit mm N MPa
%----------------------------------------------------------------
clear all;clc;
%----- Topology -------------------------------------------------
%square plate with n element each side
n_length=100;
m_width=20;
num=0;
for j=1:m_width
    for i=1:n_length
        num=num+1;
        Enode(num,:)=[num (j-1)*(n_length+1)+i (j-1)*(n_length+1)+i+1 (j)*(n_length+1)+i+1 (j)*(n_length+1)+i];
        ex(num,:)=[(i-1)*5 i*5 i*5 (i-1)*5];%unit mm
        ey(num,:)=[(j-1)*5 (j-1)*5 j*5 j*5];
        if i*5>=0 && i*5<200   
             t(num)=0.5+(3-0.5)/200*i*5;
        elseif i*5>=200 && i*5<300   
            t(num)=3;
        elseif i*5>=300 && i*5<=500 
            t(num)=0.5+(3-0.5)/200*(500-i*5);
        end
    end
end

% Enode=[1	1 2 5 4;
% 2	2 3 6 5;
% 3	5 6 9 8;
% 4	4 5 8 7];
ndof=3;
Edof=caldof(Enode,ndof);
% ex=[0 1 1 0;
% 1 2 2 1;
% 1 2 2 1;
% 0 1 1 0];
% ey=[0 0 1 1;
% 0 0 1 1;
% 1 1 2 2;
% 1 1 2 2];

%----- Element stiffness ----------------------------------------
E=2.1*10^5; %2.1e5MPa
v=0.3;
D=hooke(E,v);
% t=2;
ep=[t];
nie=size(Enode,1); 
for i=1:nie
Ke(:,:,i)=platre(ex(i,:),ey(i,:),ep(i),D); 
end

%----- Assemble Ke into K ---------------------------------------
K=zeros(max(max(Edof))); K=assem(Edof,K,Ke);

%----- load vector f and boundary conditions bc -----------------
f=zeros(max(max(Edof)),1);	f(3184)=-400;

num=0;
for i=0:20 
    num=num+1;
    boundary_node(num)=(i)*101+1;
    num=num+1;
    boundary_node(num)=(i+1)*101;
end
for i=1:length(boundary_node)
    bc((i-1)*3+1,:)=[3*(boundary_node(i)-1)+1 0];
    bc((i-1)*3+2,:)=[3*(boundary_node(i)-1)+2 0];
    bc((i-1)*3+3,:)=[3*(boundary_node(i)-1)+3 0];
end
    


%----- Solve the system of equations and compute reactions ------
[a]=solveq(K,f,bc);

%----- Postprocess ----------------------------------------------
Ed=extract(Edof,a);
num=0;
for i=1:21
    for j=1:101
        num=num+1;
        x(i,j)=(j-1)*5;
        y(i,j)=(i-1)*5;
        z(i,j)=abs(a((num-1)*3+1));
    end
end
surf(x,y,z)
xlabel('length(mm)');
ylabel('width(mm)');
zlabel('displacement(mm)');
%------------------------ end -----------------------------------