HOW DO I DO THAT IN MATLAB SERIES?

In this series, I am answering questions that students have asked me about MATLAB.

TOPIC
SUMMARY
INTRODUCTION
INPUTS
DISPLAYING INPUTS
THE CODE
DISPLAYING OUTPUTS

TOPIC

Example showing the use of matrix operations in engineering problems. Finite Element Analysis is a computerized method for predicting how a body will react to environmental factors such as forces. Depending on the material of the body, the body has a stiffness, K. The behaviour (deformation, X) of the body under the influence of set of forces, F is given by the relation F=K*X.

SUMMARY

Language : Matlab 2008a; Authors : Sri Harsha Garapati, Daniel Miller, Autar Kaw; Mfile available at Last Revised : January 17, 2012; Abstract: This program shows you an example of using matrix operations in solving engineering problems

clc
clear all

INTRODUCTION

disp('ABSTRACT')
disp('   This program shows you an example of using matrix operations in')
disp(' solving engineering problems ')

disp(' ')
disp('AUTHOR')
disp('   Sri Harsha Garapati, Daniel Miller and')
disp('Autar K Kaw of http://autarkaw.wordpress.com')
disp(' ')
disp('MFILE SOURCE')
disp('   http://numericalmethods.eng.usf.edu/blog/FEM_example5_blog.m')
disp(' ')
disp('LAST REVISED')
disp('   January 17, 2012')
disp(' ')

ABSTRACT
   This program shows you an example of using matrix operations in
 solving engineering problems 
 
AUTHOR
   Sri Harsha Garapati, Daniel Miller and
Autar K Kaw of http://autarkaw.wordpress.com
 
MFILE SOURCE
   http://numericalmethods.eng.usf.edu/blog/FEM_example5_blog.m
 
LAST REVISED
   January 17, 2012

INPUTS

% stiffness matrix [s] is in kips/inch
s=[2 0.1 0.2; 0.1 0.002 2.1; 0.2 2.1 0.03] .*10^3;

% force matrix [f] is in pounds
f=[9200; 42100; 105630];

DISPLAYING INPUTS

disp('INPUTS')
disp(' Stiffness Matrix,s')
% printing matrix s
disp(s)
disp('Force Matrix, F')
% printing matrix f
disp(f)

INPUTS
 Stiffness Matrix,s
        2000         100         200
         100           2        2100
         200        2100          30

Force Matrix, F
        9200
       42100
      105630

THE CODE

% convert the [s] matrix to lbs/in
s=s*10^3;
% using the relationship [f]=[k][x] we'll solve for [x]
% displacment matrix is [x] (inches)
x=inv(s)*f;

DISPLAYING OUTPUTS

disp('  ')
disp('OUTPUTS')
disp('  Output displacment matrix [x] (in)')
% printing matrix x
disp(x)
% finding the maximun displacement
max_disp=max(x);
fprintf('  The maximun displacement is %g in\n\n',max_disp)

  
OUTPUTS
  Output displacment matrix [x] (in)
    0.0001
    0.0500
    0.0200

  The maximun displacement is 0.0500048 in