%% Function name
%       stress_ltog

%% Revised:
%       21 January 2014

%% Author
%       Casey McKenzie, Trey Moore, & Autar Kaw
%       Section: All
%       Semester: Fall 2012

%% Purpose
%       Given the local stresses and the angle of the ply for a unidirectional
%       lamina, output the global stresses

%% Usage 
%       function [stress_glo] = stress_ltog(stress_loc,angle)
% Input variables
%       stress_loc=vector of local stress applied to unidirectional lamina
%       [stress_loc]=[s1;s2;s12]
%       s1=longitudinal local stress
%       s2=transverse local stress
%       s12=in-plane local stress
%       angle=angle of ply in degrees
% Output variables 
%       stress_glo=vector of global stress applied to unidirectional lamina
%       [stress_glo]=[sx;sy;sxy]
% Keyword
%       local stress matrix
%       global stress matrix
%       transformation of stress

%% License Agreement
%       http://www.eng.usf.edu/~kaw/OCW/composites/license/limiteduse.pdf

%% Testing code
clc
clear all
%% Inputs
[stress_loc]=[1.714;-2.714;-4.165];
fprintf('\nLongitudinal Local Stress: %g ',stress_loc(1))
fprintf('\nTransverse Local Stress: %g ',stress_loc(2))
fprintf('\nIn-Plane Local Stress: %g \n\n\n',stress_loc(3))
%% Test 1
% Testing for individual angle
% Input desired angle in degrees
angle=60;
% Call function: strain_ltog
[stress_glo] = stress_ltog(stress_loc,angle);
% Results for a particular angle
fprintf('\n\nAngle of Lamina: %G\n\n',angle)
disp('    Global Stress for Lamina')
disp('_________________________________')
fprintf('\n sx   | %G\n sy   | %G\n sxy  | %G\n\n\n\n',...
    stress_glo(1),stress_glo(2),stress_glo(3))
%% Test 2
% Table of Local Stress of an Angle Lamina
% as a Function of Fiber Angle
for i=1:5:91
    angle(i)=i-1;
    [stress_glo] = stress_ltog(stress_loc,angle(i));
    sx(i)=stress_glo(1);
    sy(i)=stress_glo(2);
    sxy(i)=stress_glo(3);
end
disp('           Global Stress for Lamina')
disp('______________________________________________________')
disp('  angle          sx          sy          sxy  ')
for i=1:5:91
    fprintf('\t%3.0f |\t %7.4f |\t %7.4f |\t %7.4f \n',angle(i),sx(i),sy(i),sxy(i))
end
%% Test 3
% Graph of Local Stress of an Angle Lamina
% as a Function of Fiber Angle
for i=1:1:91
    angle(i)=i-1;
    [stress_glo] = stress_ltog(stress_loc,angle(i));
    sx(i)=stress_glo(1);
    sy(i)=stress_glo(2);
    sxy(i)=stress_glo(3);
end
hold on
plot(angle,sx,'b','LineWidth',2)
plot(angle,sy,'r','LineWidth',2)
plot(angle,sxy,'m','LineWidth',2)
grid
legend('sx','sy','sxy')
title('Global Stress vs. Fiber Angle')
xlabel('Angle (degrees)')
ylabel('Global Stress')
hold off