Inverting Shifted Laplace function

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SUMMARY

The discussion focuses on inverting the shifted Laplace transform in the context of beam deflection analysis. The user has derived the Laplace transform of the beam displacement, represented as L{y(x)} = Y(x) = [(Mge-sx0)/(EILs5)] * (1-e-sL) - (Mg(x0 + L/2))/(EIs3) - (Mg)/EIs4. The challenge lies in inverting the first term involving the shift, specifically [(Mge-sx0)/(EILs5)] * (1-e-sL). The user seeks guidance on the initial steps to perform this inversion accurately.

PREREQUISITES
  • Understanding of Laplace transforms and their properties
  • Familiarity with beam deflection equations and mechanics
  • Knowledge of differential equations related to structural analysis
  • Experience with Mellin inversion integrals
NEXT STEPS
  • Study the properties of shifted Laplace transforms in detail
  • Review the derivation of the Mellin inversion integral
  • Practice inverting Laplace transforms with varying shift parameters
  • Explore beam deflection problems using MATLAB or similar computational tools
USEFUL FOR

Students and professionals in mechanical engineering, particularly those focused on structural analysis and dynamics, will benefit from this discussion. It is especially relevant for those working with Laplace transforms in the context of beam deflection problems.

danmel413
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Homework Statement


A beam is supported at one end, as shown in the diagram (PROBLEM 11 page 281 of Lea, 159 of the course pack). A block of mass M and length l is placed on the beam, as shown. Write down the known conditions at x = 0. Use the Laplace transform to solve for the beam displacement.

Homework Equations


I've gotten almost the entire way through the problem using the differential equations for beam deflections (most relevant ones given here: http://www.me.berkeley.edu/~lwlin/me128/BeamDeflection.pdf (8.4 and 8.50), to get to a Laplace transform I now have to invert:

L{y(x)} = Y(x) = [(Mge-sx0)/(EILs5)] * (1-e-sL) - (Mg(x0 + L/2))/(EIs3) - (Mg)/EIs4). (This is correct, I have the solutions).

The general shift of a Laplace transform: L{S(t-t0)f(t-t0)}=e-st0)F(s) for t0 > 0

The Mellin inversion integral: f(t) = 1/(2πi) ∫F(s)estds from γ-i∞ to γ+i∞

The Attempt at a Solution


So up in my first equation, the only part that can't be inverted easily is the first term which has to be shifted. The solution doesn't walk through the inversion, just gives the answer, which is annoying. It's this part:[(Mge-sx0)/(EILs5)] * (1-e-sL). I'm working in x instead of t, of course, and my F(s) would be [(Mg)/(EILs5)] * (1-e-sL), and of course the other part of the integral would be e-sx0. Can someone put me on the first step to getting through this?
 
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Multiply it out and you get two terms, one with a shift X0 and one with a shift (X0+L).
 

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