Mechanical Engineering, Indian Institute of
Science, Bangalore 560 012, India
Optimization hinders evolution!
ME256
Variational methods and structural optimization
Jan.-May, 2008
Instructor: G. K.
Ananthasuresh, Room 106, ME Building, suresh at
mecheng.iisc.ernet.in
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Homework #8
Assigned: Mar. 24, 2009
Due: Mar. 31, 2009
Points: 40
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20 points
By following the derivations we did in the lectures for the minimum characterization of the free vibration problem
of a taut string and a beam and their Rayleigh quotients, repeat this for the axial vibration of a bar. Start with
the kinetic and potential energies for an uloaded bar, use Hamilton's principle to write the dynamic equation of
motion, use separation of variables technique, and obtain the eigenvalue problem. Then, proceed with the minimum
characterization theorem and prove it. The last step is to obtain the Rayleigh quotient.
For extra credit of 20 points write down the problem of designing strongest column for
specified volume of material and solve it analytically as much as you can. Numerical solution will fetch you
additional extra credit!
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20 points
Submit a precise mathematical statement of your project problem in the form of a calculus of variations problem.
You should write it in the standard form by clearly identifying the objective function, design variable(s),
governing equation for state variable(s), resource constraints, and other constraints. Do not forget to write the
data needed for the problem.