%% Function name
%       stress_gtol

%% Revised:
%       16 January 2014

%% Author
%       Abigail Lambert, Trey Moore, & Autar Kaw
%       Section: All
%       Semester: Fall 2012

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

%% Usage 
%       function [stress_loc] = stress_gtol(stress_glo,angle)
% Input variables
%       stress_glo=vector of global stress applied to unidirectional lamina
%       [stress_glo]=[sx;sy;sxy]
%       sx=longitudinal global stress
%       sy=transverse global stress
%       sxy=in-plane global stress
%       angle=angle of ply in degrees
% Output variables 
%       stress_loc=vector of local stress applied to unidirectional lamina
%       [stress_loc]=[s1;s2;s12]
% 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_glo]=[1.2;  3.6; .023];
fprintf('\nLongitudinal Global Stress: %g ',stress_glo(1))
fprintf('\nTransverse Global Stress: %g ',stress_glo(2))
fprintf('\nIn-Plane Global Stress: %g \n\n\n',stress_glo(3))
%% Test 1
% Testing for individual angle
% Input desired angle in degrees
angle=60;
% Call function: stress_gtol
[stress_loc] = stress_gtol(stress_glo,angle);
% Results for a particular angle
fprintf('\n\nAngle of Lamina: %G\n\n',angle)
disp('    Local Stress for Lamina')
disp('_________________________________')
fprintf('\n s1   | %G\n s2   | %G\n s12  | %G\n\n\n\n',...
    stress_loc(1),stress_loc(2),stress_loc(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_loc] = stress_gtol(stress_glo,angle(i));
    s1(i)=stress_loc(1);
    s2(i)=stress_loc(2);
    s12(i)=stress_loc(3);
end
disp('                     Local Stress for Lamina')
disp('__________________________________________________________________________')
disp(' angle           s1                 s2             s12  ')
for i=1:5:91
    fprintf('\t%2.0f |\t  %E |\t %E |\t %E \n',angle(i),s1(i),s2(i),s12(i))
end
%% Test 3
% Graph of Local Strains of an Angle Lamina
% as a Function of Fiber Angle
for i=1:1:91
    angle(i)=i-1;
    [stress_loc] = stress_gtol(stress_glo,angle(i));
    s1(i)=stress_loc(1);
    s2(i)=stress_loc(2);
    s12(i)=stress_loc(3);
end
hold on
plot(angle,s1,'b','LineWidth',2)
plot(angle,s2,'r','LineWidth',2)
plot(angle,s12,'m','LineWidth',2)
grid
legend('s1','s2','s12')
title('Local Stress vs. Fiber Angle')
xlabel('Angle (degrees)')
ylabel('Local Stress')
hold off