%% Function name
%        principalstresses & principalstrains

%% Revised: 
%       16 January 2014

%% Author
%       Adam Wolfe, Trey Moore, & Autar Kaw
%       Section: All
%       Semester: Fall 2012

%% Purpose
%       Given the global stresses acting on the lamina, output the 
%       longitudinal, transverse and in plane principal stresses of a lamina
%       &
%       Given the global strains acting on the lamina, output the 
%       longitudinal, transverse and in plane principal strains of a lamina

%% Usage
%       function [ps1,ps2,tmax] = principalstresses(stress_glo)
%       &
%       function [pe1,pe2,gmax] = principalstrrain(strain_glo)
% Input variables
%       stress_glo=vector of global stress applied to unidirectional lamina
%       [stress_glo]=[sx;sy;txy]
%       sx=longitudinal global stress
%       sy=transverse global stress
%       txy=in-plane shear stress
%       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
% Output variables
%       ps1=principal stress in direction 1 [pricipal stress 1, angle]
%       ps2=principal stess in direction 2 [pricipal stress 2, angle]
%       tmax=maximum shear stress [maximum shear stress, angle]
%       pe1=vector of principal strain in direction 1 [pricipal strain 1, angle]
%       pe2=vector of principal strain in direction 2 [pricipal strain 2, angle]
%       gmax=maximum shear strain [maximum shear strain, angle]
% Keyword
%       global stresses
%       principal stresses
%       global strains
%       principal strains

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

%% Testing code
clc
clear all
%% Inputs
[stress_glo]=[0.7486;-1.157;2.306]*10^6;
[strain_glo]=[0.7486;-1.157;2.306]*10^-3;
fprintf('\nLongitudinal Global Stress: %g ',stress_glo(1))
fprintf('\nTransverse Global Stress: %g ',stress_glo(2))
fprintf('\nIn-Plane Global Shear Stress: %g ',stress_glo(3))
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
% Testing for principal stresses and strains
% Call function: principalstresses
[ps1,ps2,tmax,thetaps,thetass] = principalstresses(stress_glo);
disp('  Principal Stresses for Lamina')
disp('_______________________________________')
fprintf('\n ps1      | %G\n ps2      | %G\n tmax     | %G\n thetaps  | %G\n thetass  | %G\n\n'...
    ,ps1,ps2,tmax,thetaps,thetass)
% Call function: principalstrains
[pe1,pe2,gmax,thetape,thetase] = principalstrains(strain_glo);
% Results for a particular angle
disp('  Principal Strains for Lamina')
disp('_______________________________________')
fprintf('\n pe1      | %G\n pe2      | %G\n gmax     | %G\n thetape  | %G\n thetase  | %G\n\n'...
    ,pe1,pe2,gmax,thetape,thetase)