%% Function name
%       strain_ltog

%% Revised:
%       21 January 2014

%% Author
%       Ahmad Hares, Trey Moore, & Autar Kaw
%       Section: All
%       Semester: Fall 2012

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

%% Usage 
%       function [strain_glo] = strain_ltog(strain_loc,angle)
% Input variables
%       strain_loc=vector of local strain applied to unidirectional lamina
%       [strain_loc]=[eps1;eps2;eps12]
%       eps1=longitudinal local strain
%       eps2=transverse local strain
%       eps12=in-plane local strain
%       angle=angle of ply in degrees
% Output variables 
%       strain_glo=vector of global strain applied to unidirectional lamina
%       [strain_glo]=[epsx;epsy;epsxy]
% Keyword
%       local strain matrix
%       global strain matrix
%       transformation of strains

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

%% Testing code
clc
clear all
%% Inputs
[strain_loc]=[5.206E-5;7.841E-4;1.374E-3];
fprintf('\nLongitudinal Local Strain: %g ',strain_loc(1))
fprintf('\nTransverse Local Strain: %g ',strain_loc(2))
fprintf('\nIn-Plane Local Strain: %g \n\n\n',strain_loc(3))
%% Test 1
% Testing for individual angle
% Input desired angle in degrees
angle=60;
% Call function: strain_ltog
[strain_glo] = strain_ltog(strain_loc,angle);
% Results for a particular angle
fprintf('\n\nAngle of Lamina: %G\n\n',angle)
disp('    Global Strains for Lamina')
disp('_________________________________')
fprintf('\n epsx   | %G\n epsy   | %G\n epsxy  | %G\n\n\n\n',...
    strain_glo(1),strain_glo(2),strain_glo(3))
%% Test 2
% Table of Local Strains of an Angle Lamina
% as a Function of Fiber Angle
for i=1:5:91
    angle(i)=i-1;
    [strain_glo] = strain_ltog(strain_loc,angle(i));
    epsx(i)=strain_glo(1);
    epsy(i)=strain_glo(2);
    epsxy(i)=strain_glo(3);
end
disp('           Global Strains for Lamina')
disp('______________________________________________________')
disp('  angle        epsx        epsy        epsxy  ')
for i=1:5:91
    fprintf('\t%3.0f |\t %7.4f |\t %7.4f |\t %7.4f \n',angle(i),epsx(i),epsy(i),epsxy(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;
    [strain_glo] = strain_ltog(strain_loc,angle(i));
    epsx(i)=strain_glo(1);
    epsy(i)=strain_glo(2);
    epsxy(i)=strain_glo(3);
end
hold on
plot(angle,epsx,'b','LineWidth',2)
plot(angle,epsy,'r','LineWidth',2)
plot(angle,epsxy,'m','LineWidth',2)
grid
legend('epsx','epsy','epsxy')
title('Global Strains vs. Fiber Angle')
xlabel('Angle (degrees)')
ylabel('Global Strains')
hold off