%**************************************************************************
function [U, Strain, Stress, AxialForce]=TrussStaticsFEA(x,y,z,ele,Load,Constr,Scale)
Dofs=3*size(x,2); %总自由度数
EleCount=size(ele,1); %单元总数
K=zeros(Dofs,Dofs); %总体刚度矩阵
F=zeros(Dofs,1); %总体载荷列阵
U=zeros(Dofs,1); %总体位移列阵
BarLength=BarsLength(x,y,z,ele);
figure('Name','Undeformed Truss')
RenderTruss(ele,Load,Constr,x,y,z,U,1,1,'-k',1) %绘制桁架
axis equal
figure('Name','Deformed Truss')
RenderTruss(ele,Load,Constr,x,y,z,U,0.5,0.5,'-k',1) %绘制变形后桁架
axis equal
hold on
%遍历所有单元，将各单元刚度阵分块组装到总体刚度阵
for iEle =1:EleCount
    %该单元的两个节点的编号
    n1=ele(iEle,2);n2=ele(iEle,3);
    %计算坐标变换矩阵
    R=CoordTransform([x(n1) x(n2)],[y(n1) y(n2)],[z(n1) z(n2)],BarLength(iEle));
    %计算单元刚度矩阵
    ke= BarElementKe(ele(iEle,4),ele(iEle,5),R,BarLength(iEle));
    %将各单元刚度分块组装到总刚相应位置
    K(3*n1-2:3*n1,3*n1-2:3*n1)=K(3*n1-2:3*n1,3*n1-2:3*n1)+ke(1:3,1:3);
    K(3*n1-2:3*n1,3*n2-2:3*n2)=K(3*n1-2:3*n1,3*n2-2:3*n2)+ke(1:3,4:6);
    K(3*n2-2:3*n2,3*n1-2:3*n1)=K(3*n2-2:3*n2,3*n1-2:3*n1)+ke(4:6,1:3);
    K(3*n2-2:3*n2,3*n2-2:3*n2)=K(3*n2-2:3*n2,3*n2-2:3*n2)+ke(4:6,4:6);
end
%形成载荷列阵--1、2、3、4、5、6自由度赋载荷值
for LoadNum=1:size(Load,1)
   for i=2:4
      F(3*Load(LoadNum)+i-4,1)=Load(LoadNum,i);
   end
end
%施加约束--乘大数法
for iConstr=1:size(Constr,1)
   for j=2:4
      if ~isnan(Constr(iConstr,j))
         K(3*Constr(iConstr,1 )+j-4,3*Constr(iConstr,1)+j-4)=...
         1e12*K(3*Constr(iConstr,1 )+j-4,3*Constr(iConstr,1)+j-4);
         F(3*Constr(iConstr,1)+j-4)=1e12*Constr(iConstr,j)*...
         K(3*Constr(iConstr,1 )+j-4,3*Constr(iConstr,1)+j-4);
      end
   end
end
U=K\F; %全局坐标系下位移
for iEle =1:EleCount
    %计算杆局部坐标下的位移  
    n1=ele(iEle,2);n2=ele(iEle,3);
    R=CoordTransform([x(n1) x(n2)],[y(n1) y(n2)],[z(n1) z(n2)],BarLength(iEle));
    localU = R*[U(3*n1-2:3*n1,1);U(3*n2-2:3*n2,1)];
    Strain(1, iEle)=[-1/BarLength(iEle) 1/BarLength(iEle)]*localU; %应变
    Stress(1, iEle)=ele(iEle,5)* Strain(1, iEle); %应力
    AxialForce(1, iEle)=ele(iEle,4)* Stress(1, iEle); %轴力
end
%保存位移，应力与轴力到文本文件
fp=fopen('Result.txt','a');
str = [char(13,10)','U',' ',num2str(U'),char(13,10)','Stress',' ',...
   num2str(Stress),char(13,10)','AxialForce',' ',num2str(AxialForce)];
fprintf(fp,str);
fclose(fp);
RenderTruss(ele,Load,Constr,x,y,z,U,1,1,'-.b',Scale) %绘制变形后桁架
figure
AxisForcePlot(ele,Load,Constr,x,y,z,U,1,2.5,'-b',Scale,AxialForce)
axis equal
end %主程序结束