truss.m

是个好东西

function truss  %  （定义新的函数truss）
% This function analyze the problem of plane stress use triangle elements 
% the variables lists:
%       node  -------  node definition
%       element -----  element definition
%       material ----  material definition
%       K -----------  global stiffness matrix                -|
%       f -----------  global node force vector                |  [K]{delta}={f}
%       delta -------  global node displacement vector -|
%       bc ----------  boundary condition 
%       nf ----------  node force
%       file_in -----  input file name
%       file_out ----  output file name
%       fid_in ------  input file ID
%       fid_out -----  output file ID
global node element material K bc bc_number nf_number nf  node_number element_number %（定义全局变量）
file_in='myinput.txt';           %input('input file name:','s' );
file_out='myoutput.txt';          %input('output file name:','s');
fid_in  = fopen( file_in, 'r' ) ;   % open input file 
inputdata(fid_in);
fclose( fid_in ) ;    %close the input file which has been opened
K=sparse(node_number*3,node_number*3);%（创建稀疏矩阵K）
f = zeros(node_number*3,1) ;%（创建f）
for ie=1:1:element_number
   k=StiffnessMatrix( ie ) ;  % (调用函数StiffnessMatrix)
   AssembleStiffnessMatrix( ie, k ) ;% (调用函数AssembleStiffnessMatrix)
end
for inf=1:1:nf_number
  n = nf( inf, 1 ) ;
  d = nf( inf, 2 ) ;
  f( (n-1)*3 + d ) = nf( inf, 3 ) ;
end
for ibc=1:1:bc_number
  n = bc(ibc, 1 ) ;
  d = bc(ibc, 2 ) ;
  m = (n-1)*3 + d ;
  f(m) = bc(ibc, 3)* K(m,m) * 1e20 ;
  K(m, m) = K(m, m) * 1e20 ;
end
delta = K \ f ;%（解方程组,得位移delta）
fid_out = fopen( file_out, 'w' ) ; % open the output file
fprintf( fid_out, '节点位移\n');
for i=1:1:node_number
   fprintf( fid_out, 'node = %5d, x = %.8e, y = %.8e, z = %.8e\n', ...
   i, delta((i-1)*3+1), delta((i-1)*3+2) , delta((i-1)*3+3)) ;  % output the node displacement
end
fclose(fid_out) ; % close the output file
return ;%（function truss结束）