# Plane Stress and Rotation

## ES 302 Assignment 3

Using Matlab, set up a computer program as described in
Problem 6.C1, on page 407 in Beer and Johnston
*Mechanics of Materials*, second edition. However,
only work Problem 6.4 which you did for homework.
Use mnemonic symbols such as **sigx, sigy, tauxy**, and **theta**.
Use an **input** statement to get the above four values:

sigx = input(' SigmaX: ');

Don't forget to convert your input angle from degrees to radians.
Since cos(2*theta) and sin(2*theta) are used more than once, equate
these expressions new symbols such as **cos2** and **sin2**.

Print out the rotation angle on one line and then make a table to
show the three original stresses and the rotated stresses for
Problem 6.4.

As usual, put your name, date, and subject in the program with lines such as:

% print the results
fprintf('\n Plane Stress')
fprintf('\n Your name, ES 302, ')
disp(date)

When the program is running properly, surround it with a **while**
loop so you can easily use it for another problem:
contin = 'y';
while (contin(1) == 'y')

at the top, and
contin=input(' Another problem? ','s');
end

at the bottom. Notice the this input statement is different than the
previous ones. It has an **s** argument because now you are reading a
string variable. Furthermore, **contin(1)** only selects the first letter
so you can enter either y or yes.
The output should look like this:
Plane Stress Rotation
Your name, ES 302, 29-Oct-1998
Rotation angle 150.0 degrees
Sigma X Sigma Y Tau XY
Ksi Ksi Ksi
Original -6.00 12.00 9.00
Rotated ... ... ...

Copy the output from Matlab and paste it into the bottom of your
Matlab program. Attach the regular solution to Problem 6.4 that you
previously turned in.
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Last revised: March 17, 2000