%% Function name
%       maximumstress

%% Revised
%       16 January 2014

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

%% Purpose
%       Given ultimate strengths of a unidirectional lamina, angle of the 
%       ply in degrees, and the global stresses acting on the lamina, output
%       the strength ratio of the lamina based on maximum strain theory

%% Usage
%       function [SR] = maximumstress(stress_glo,angle,strength)
% 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
%       angle=angle of ply in degrees
%       strength=vector of the five ultimate strain strengths of the 
%                unidirectional lamina
%       [strength]=[s1tu s1cu s2tu s2cu s12u] 
%       s1tu=ultimite longitudinal tensile strength
%       s1cu=ultimite longitudinal compressive strength
%       s2tu=ultimite transverse tensile strength
%       s2cu=ultimite transverse compressive strength
%       s12u=ultimite in-plane shear strength
% Output variable
%       SR=Strength Ratio
% Keyword
%       maximum stress failure theory
%       strength ratio
%       angle ply

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

%% Testing Code
clc
clear all
%% Inputs
% Material: Boron/Epoxy
[stress_glo]=[0.7486;-1.157;2.306]*10^6;
[strength]=[1260E6 2500E6 61E6 202E6 67E6];
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('\nUltimate Longitudinal Tensile Strength: %g ',strength(1))
fprintf('\nUltimate Longitudinal Compressive Strength: %g ',strength(2))
fprintf('\nUltimate Transverse Tensile Strength: %g ',strength(3))
fprintf('\nUltimate Transverse Compressive Strength: %g ',strength(4))
fprintf('\nUltimate In-Plane Shear Strength: %g ',strength(5))
%% Test 1
% Testing for individual angle
% Input desired angle in degrees
angle=60;
% Call function: maximumstress
[SR] = maximumstress(stress_glo,angle,strength);
% Results for a particular angle
fprintf('\n\nAngle of Lamina: %G\n\n',angle)
disp('  Strength Ratio for Lamina')
disp('_______________________________________')
fprintf('\n SR   | %G\n\n\n\n',SR)
%% Test 2
% Table of Strength Ratio of an Angle Lamina
% as a Function of Fiber Angle
for i = 1:10:91
    angle(i)=i-1;
    [SR] = maximumstress(stress_glo,angle(i),strength);
    sr(i)=SR;
end
disp('Angle Lamina Strength Ratio')
disp('________________________________')
disp('   angle         SR')
for i=1:10:91
   fprintf('   \t%2.0f    |\t %3.4f\n', angle(i),sr(i))
end
%% Test 3
% Graphs of Strength Ratio of an Angle Lamina
% as a Function of Fiber Angle
for i=1:1:91
    angle(i)=i-1;
    [SR] = maximumstress(stress_glo,angle(i),strength);
    sr(i)=SR;
end
% Plot of strength ratio
figure
hold on
plot(angle,sr,'b','LineWidth',2)
grid
legend('Strength Ratio (Maximum Stress Failure Theory)')
title('Strength Ratio vs. Fiber Angle')
xlabel('Angle (degrees)')
ylabel('Strength Ratio (Maximum Stress Failure Theory)')
hold off