clear all;close all;clc;
E=210e3;
% t=2;% I=1/12*100*t^3;
L=5;
ele_num=500/L;
%*****变截面的特殊设置
for i=1:ele_num
    if i*5>=0 && i*5<200
        t(i)=0.5+(i*5)*(3-0.5)/200;
    elseif i*5>=200 && i*5<300
        t(i)=3;
    elseif i*5>=300 && i*5<=500
        t(i)=3-(3-0.5)/200*(i*5-300);
    end
    I(i)=1/12*100*t(i)^3;
end
for i=1:ele_num
    ke(:,:,i)=BeamElementStiffness(E,I(i),L); %*****变截面梁的特殊设置
end

K=zeros((ele_num+1)*2);
for i=1:ele_num
%     ke=BeamElementStiffness(E,I,L);
    K=BeamAssemble(K,ke(:,:,i),i,i+1);
end

k=[K(3:(ele_num+1)*2-2,3:(ele_num+1)*2-2)];
f=zeros(2*(ele_num-1),1);
f(ele_num-1)=-400;
u=k\f;
U=zeros((ele_num+1)*2,1);
U(3:ele_num*2)=u;
for i=1:ele_num
    Fe(i,:)=ke(:,:,i)*U((i-1)*2+1:(i-1)*2+4);
end
F=K*U;
figure;
x = [0 : L:500]';
M=Fe(:,2);
M(ele_num+1)=-Fe(end,4);
hold on;
title('Bending Moment Diagram');
plot(x,M);
y1 = zeros(1,ele_num+1);
plot(x,y1,'k')
xlabel('length(mm)')
ylabel('Moment(N.mm)')
title('moment diagram with varing thickness');
%plot disp
figure;
hold on;
title('Displacment Diagram');
for i=1:length(x)
    disp_plot_vary(i)=U(2*(i-1)+1);
end
plot(x,disp_plot_vary);