Calculus: Verify Thick Walled Cylinder Equations

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Ketav
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Homework Statement



I have a system of two ordinary differential equations as shown below. I have to prove that the Lame's exact solutions for a thick walled cylinder loaded by internal pressure satisfies the equations.

The next step is to integrate the equations to obtain an equation for U and radial stress

Handwritten-style typeset equations in red: du/dr and dσrr/dr expressed in terms of u, r, E, v and σrr, then σφφ in terms of σrr, followed by given Lame solutions for σφφ, σrr and u in terms of a, b, P, r, E and v.

Homework Equations


How should i go about the solution of this problem

The Attempt at a Solution


I have tried to find solutions for this but get stuck after the substitution of all given info[/B]
 
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I have tried to substitute the equations but for the hoop stress I obtain the relationship between b and r as one.
If anyone has any suggestions, I will be very thankful to you.
I have tried solving the differential equations however, i get to a point where I get d2u/dr2 + i/r du/dr + u/r=0 and get stuck with integration constants
 
Ketav said:
I have tried to substitute the equations but for the hoop stress I obtain the relationship between b and r as one.
If anyone has any suggestions, I will be very thankful to you.
I have tried solving the differential equations however, i get to a point where I get d2u/dr2 + i/r du/dr + u/r=0 and get stuck with integration constants
This is really a math problem. I'm going to move it to the math homework forum. Please show us your work in doing the substitutions.
 
So I've done this,

now I am confused about the integration. its a double integral but the boundary conditions are for r and sigma r
Handwritten-style derivation of thick-walled cylinder equations: Equation 1 du/dr and Equation 2 d(sigma_rr)/dr, substitution of sigma_rr and its derivative, leading to a second-order equation in u with terms in u/r squared and du/dr equal to zero.