%% Function name
%       strain_gtol

%% Revised:
%       16 January 2014

%% Author
%       Howard Fox, Trey Moore, & Autar Kaw
%       Section: All
%       Semester: Fall 2012

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

%% Usage 
%       function [strain_loc] = strain_gtol(strain_glo,angle)
% Input variables
%       strain_glo=vector of global strain applied to unidirectional lamina
%       [strain_glo]=[epsx;epsy;epsxy]
%       epsx=longitudinal global strain
%       epsy=transverse global strain
%       epsxy=in-plane global strain
%       angle=angle of ply in degrees
% Output variables 
%       strain_loc=vector of local strain applied to unidirectional lamina
%       [strain_loc]=[eps1;eps2;eps12]
% 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_glo]=[1.2;3.6;0.023];
fprintf('\nLongitudinal Global Strain: %g ',strain_glo(1))
fprintf('\nTransverse Global Strain: %g ',strain_glo(2))
fprintf('\nIn-Plane Global Strain: %g \n\n\n',strain_glo(3))
%% Test 1
% Testing for individual angle
% Input desired angle in degrees
angle=60;
% Call function: strain_gtol
[strain_loc] = strain_gtol(strain_glo,angle);
% Results for a particular angle
fprintf('\n\nAngle of Lamina: %G\n\n',angle)
disp('    Local Strains for Lamina')
disp('_________________________________')
fprintf('\n eps1   | %G\n eps2   | %G\n eps12  | %G\n\n\n\n',...
    strain_loc(1),strain_loc(2),strain_loc(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_loc] = strain_gtol(strain_glo,angle(i));
    eps1(i)=strain_loc(1);
    eps2(i)=strain_loc(2);
    eps12(i)=strain_loc(3);
end
disp('                     Local Strains for Lamina')
disp('__________________________________________________________________________')
disp(' angle           eps1               eps2            eps12  ')
for i=1:5:91
    fprintf('\t%2.0f |\t  %E |\t %E |\t %E \n',angle(i),eps1(i),eps2(i),eps12(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_loc] = strain_gtol(strain_glo,angle(i));
    eps1(i)=strain_loc(1);
    eps2(i)=strain_loc(2);
    eps12(i)=strain_loc(3);
end
hold on
plot(angle,eps1,'b','LineWidth',2)
plot(angle,eps2,'r','LineWidth',2)
plot(angle,eps12,'m','LineWidth',2)
grid
legend('eps1','eps2','eps12')
title('Local Strains vs. Fiber Angle')
xlabel('Angle (degrees)')
ylabel('Local Strains')
hold off