Eigenvalues of a string with fixed ends and a mass in the middle

AI Thread Summary
To determine the eigenfrequencies and mode shapes of a taut string with fixed ends and a mass in the middle, the wave equation must be set up correctly, incorporating the tension, lineal density, and the mass as a Dirac delta function. The user is struggling to adapt the standard wave equation format to include the discrete mass, which complicates the determination of eigenvalues. A suggested resource was provided to help analyze the single-mass-loaded string problem, indicating that the user is on the right track. Further guidance on solving the differential equation is needed to progress. Understanding the implications of the boundary conditions and the mass's effect on the wave equation is crucial for finding a solution.
Frank93
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Hi there. First of all, sorry for my bad english. I ´m trying to solve next exercise, from Vibrations and Waves in Continuos Mechanical Systems (Hagedorn, DasGupta): Determine the eigenfrequencies and mode-shapes of transverse vibration of a taut string with fixed ends and a discrete mass in the middle.

I set next wave equation:

T * ∂^2 Y/ ∂^2 X = ( ρ + m*δ(x-L/2) ) * ∂^2 Y/ ∂^2 t

where
T: tension, ρ: lineal density of the string, m: mass of the particle in the middle of the string, δ: Dirac delta, L: length of the string, and the boundary conditions are Y(0,t)=0 and Y(L,t)=0.


I don`t know how to continue this, because to determine the eigenvalues, I need the wave equation, but it isn`t the usual Y(x,t) = [A*Cos(k*x)+B*Sin(k*x)]*[C*Cos(w*t)+D*Sin(w*t)]. How can I solve this differntial equation? Or another way to solve this?
 
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Thank you drvrm!
 
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