Finite Element Analysis for a 2D Truss Coding Help

Write the generalized Matlab program to solve any 2D truss. Apply this program to solve Problem 3.20 using whole structure (don’t utilize the symmetry). Modify the program provided for HW1 to convert into generalize 2D truss-solver. The output of the program should have displacements (all nodes), stresses (all elements), unknown reactions, internal forces (all elements), and type of internal forces (all elements).

I have this code set up from a similar problem but I am having trouble converting it for this problem. All help would be great!

clear all

clc

close all

nodeConn = [3 1; 1 2];

elemProp = [1000; 2000];

disp = [NaN;20e-3; 0.0];

force = [0.0; NaN; NaN];

[disp, force, elemForce, elemForceType] = AEM461_HW1_Spring(nodeConn, elemProp, disp, force)

function [disp, force, elemForce, elemForceType] = AEM461_HW1_Spring(nodeConn, elemProp, disp, force)

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%my first FEM program for springs

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

node = unique(nodeConn); % total number of nodes

noElem = size(nodeConn,1); % total number of elements

GlobalK = zeros(length(node),length(node));

for elemCount = 1:noElem

node1Pos = find(node == nodeConn(elemCount,1)); % finding the position of node 1 in global array

node2Pos = find(node == nodeConn(elemCount,2)); % finding the position of node 2 in global array

GlobalK(node1Pos, node1Pos) = GlobalK(node1Pos, node1Pos) + elemProp(elemCount);

GlobalK(node2Pos, node2Pos) = GlobalK(node2Pos, node2Pos) + elemProp(elemCount);

GlobalK(node2Pos, node1Pos) = GlobalK(node2Pos, node1Pos) - elemProp(elemCount);

GlobalK(node1Pos, node2Pos) = GlobalK(node1Pos, node2Pos) - elemProp(elemCount);

end

dispUind = find(isnan(disp)==1);%%%% finding the indices of unknown displacements

dispKind = find(isnan(disp)==0);%%%% finding the indices of unknown forces

Kaa = GlobalK(dispUind,dispUind);

Kbb = GlobalK(dispKind,dispKind);

Kab = GlobalK(dispUind,dispKind);

Kba = GlobalK(dispKind,dispUind);

forceK = force(dispUind); %%%% known force vector

dispK = disp(dispKind); %%%% known displacement vector

modForce = forceK - Kab*dispK; %%%%modfied force vector

dispU = Kaa\modForce; %%%% unknown displacement vector

forceU = Kba*dispU + Kbb*dispK; %%%% unknown force vector

disp(dispUind) = dispU; %%%% forming total displacement vector

force(dispKind) = forceU; %%%% forming total force vector

elemForce = zeros(noElem,1); %%% initializing elemental forces

elemForceType = cell(noElem,1); %%%% initializing types of elemental forces

for elemCount = 1:noElem

node1Pos = find(node == nodeConn(elemCount,1)); % finding the position of node 1 in global array

node2Pos = find(node == nodeConn(elemCount,2)); % finding the position of node 2 in global array

dispElemVec = [disp(node1Pos); disp(node2Pos)]; %%% forming elemental displacemental vector

elemForceVec = elemProp(elemCount)*[1 -1; -1 1]*dispElemVec; %%% finding elemental force vector

elemForce(elemCount) = abs(elemForceVec(1)); %%% magnitude of the elemental force

if sign(elemForceVec(1)) == -1

elemForceType{elemCount} = 'T'; %%% elemental force is tensile

else

elemForceType{elemCount} = 'C'; %%% elemental force is compressive

end

end

Answer 1

[amir beygi]

hi man i have the same problem if u find the answer let me know