Description

Now we will clamp both ends of our beam and use a sinusoidal force (sinusoidalforces.m). The structure of our initial matrix is altered slightly in initclampedmatrix.m so that the final 2 rows are the reverse of the first two rows. Our errors are obtained through Problem 7 and are as follows for \(x=\frac{L}{2}\) against the correct solution, \[ y(x)=\frac{f}{24EI}x^2(L-x)^2-\frac{pgL^2}{\pi^4EI}(L^2\sin\frac{\pi}{L}x+\pi x(x-L)). \]

\(n\) Error Condition Number
10 0.001668593932958 805
20 0.000797116989074 10652
40 0.000389529641042 154595
80 0.000192541455493 2354357
160 0.000095718910114 36745380
320 0.000047721984204 580645427
640 0.000023826669975 9232533524
1280 0.000011904768050 147259976987
2560 0.000005949391567 2352479784190
5120 0.000002949775262 37610490062507
10240 0.000001865160826 601604110154096
20480 0.000001600275175 9615665665490997

This table implies that our error has a linear relationship to \(n\) but the condition number does not come into play as it did in Problem 5. The following plot exhibits this relationship:

The error (blue) seems to be concave up as \(n\) increase (\(h\) decreases) which suggests that the condition number may begin to have a significant effect if we tested higher values of \(n\). This plot also shows that the error is approximately proportional to \(h^2\) as claimed in the description. To get a picture of the beam itself, we modified our code a bit to problem7deflection.m:

This concludes our first project of MATH 447 Numerical Analysis II under Dr. Tim Sauer. We hope you enjoyed reading about our investigations. You may return to the project's main page here. Please download the code and try it yourself!

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