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# ME 3255 - Final Project | ||
## Due May 1 by 11:59pm | ||
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In this project you are going to solve for the shape of a beam under different loading | ||
conditions. The shape of the beam varies along the x-axis and as a function of time. | ||
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Notes: Label the plots with legends, x- and y-axis labels and make sure the plots are easy | ||
to read (you can use the `setdefaults.m` script we have used in class). All functions | ||
should have a help file and your README.md should describe each file in your repository | ||
and provide a description of each problem and each solution (use `#`-headings in your file | ||
to show the start of new problems) | ||
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You will be graded both on documentation and implementation of the solutions. | ||
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 | ||
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We will use the Euler-Bernoulli beam equation to describe the shape of the beam, the | ||
differential equation that governs the solution is: | ||
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$\frac{\partial^4 w}{\partial x^4}-\frac{P}{EI}\frac{\partial^2 w}{\partial | ||
x^2}+\frac{\rho A}{EI}\frac{\partial^2 w}{\partial t^2}=q(x)$ (1) | ||
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Where w(x,t) is the displacement of the beam away from the neutral axis as a function of | ||
position along the beam, x, and time, t, P is the transverse loading of the beam, E is the | ||
Young's modulus, I is the second moment of Inertia of the beam, $\rho$ is the density, A | ||
is the cross-sectional area, and q(x) is the transverse distributed load (for a uniform | ||
pressure, it is the applied pressure times the width of the beam, in units of | ||
force/length). | ||
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We can separate the function $w(x,t)=w(x)e^{i\omega t}$, now equation (1) becomes | ||
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$\left(\frac{\partial^4 w}{\partial x^4}-\frac{P}{EI}\frac{\partial^2 w}{\partial | ||
x^2}-\frac{\rho A \omega^{2}}{EI}w\right)e^{i\omega t}=\frac{q(x)}{EI}$ (2) | ||
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For the simply-supported beam shown in Figure 1, the boundary conditions are: | ||
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$w(0)=w(L)=0$ | ||
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$w''(0)=w''(L)=0$ | ||
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The material is aluminum, E=70 GPa, $\rho$=2700 kg/m$^3$. The bar is 1-m-long with a base | ||
width, b=0.1 m, and height, h=0.01 m, and the second moment of inertia, | ||
I=$\frac{bh^3}{12}$. | ||
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1. Analytically solve for the shape of the beam if q(x)=cst, P=0, and $\omega$=0 and | ||
create a function called `shape_simple_support.m` that returns the displacement w(x) given | ||
q and x | ||
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``` | ||
w=shape_simple_support(x,q); | ||
``` | ||
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a. Plot q vs the maximum deflection, $\delta x$, of the beam | ||
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b. Use a Monte Carlo model to determine the mean and standard deviation for the | ||
maximum deflection $\delta x$ if b and h are normally distributed random variables | ||
with 0.1 % standard deviations at q=50 N/m. | ||
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3. Now use the central difference approximation to set up a system of equations for the | ||
beam for q(x)=cst, P=0, and $\omega=0$. Use the boundary conditions with a numerical | ||
differentiation to determine the valuea of the end points | ||
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a. set up the system of equations for 6 segments as a function of q | ||
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b. set up the system of equations for 10 segments as a function of q | ||
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c. set up the system of equations for 20 segments as a function of q | ||
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d. solve a-c for q=1,10,20,30,50 and plot the numerical results of q vs $\delta x$ | ||
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e. Comment on the results from the analytical and numerical approaches (if you used | ||
functions then provide help files, if you used scripts, then describe the steps used) | ||
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4. Now set up the system of equations using a central difference method if P>0 and | ||
$\omega=0$ | ||
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a. set up the system of equations for 6 segments as a function of q and P | ||
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b. set up the system of equations for 10 segments as a function of q and P | ||
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c. set up the system of equations for 20 segments as a function of q and P | ||
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d. solve a-c for q=1,10,20,30,50 and plot the numerical results of q vs $\delta x$ for | ||
P=0, 100, 200, 300 (4 lines, labeled as P=0,P=100,...) | ||
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5. Now set up an eigenvalue problem to solve for the natural frequencies of the simply | ||
supported beam if P=0 and q=0. | ||
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a. set up the system of equations for 6 segments | ||
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b. set up the system of equations for 10 segments | ||
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c. set up the system of equations for 20 segments | ||
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d. solve for the natural frequencies ($\omega_{1}$, $\omega_{2}$,...) | ||
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e. Plot the shape of the beam for the first 3 natural frequencies | ||
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6. (Bonus 5pt) Create a function to return the system of equations for the eigenvalue | ||
problem as a function of P, if P>0. Then, plot the lowest natural frequency vs the applied | ||
load P. | ||
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