Mechanical Engineering, Indian Institute of Science, Bangalore 560 012, India
Optimization hinders evolution!
ME256 Variational Methods and Structural Optimization Jan.-May, 2012
Instructor: G. K. Ananthasuresh, Room 106, ME Building, suresh at mecheng.iisc.ernet.in
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Syllabus and notes
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Syllabus, schedule, and notes
Topics to be covered in this course--not necessarily in this order.
  • Motivating examples of calculus of variations
  • Mathematical preliminaries: normed vectors spaces, functionals (continuous and linear), directional derivative, concept of variation, Gateaux variation, Frechet differential, etc.
  • Fundamental lemmas of calculus of variation
  • Euler-Lagrange (E-L) equations
  • Applications of E-L equation
  • Extensions of E-L equation to multiple derivatives, independent variables, multiple state variables
  • Isoperimetric problems--global and local (finite subsidiary) constraints
  • Applications of optimizing functionals subject to constraints
  • Applications in mechanics: strong and weak forms of governing equations
  • Variable end conditions--transversality conditions
  • Size optimization of a bar for maximum stiffness
  • Self-adjointness and optimization with weak variational form
  • Optimization with side constraints (variable bounds)
  • Worst load scenario for an axially loaded stiffest bar
  • Min-max type problem with stress constraints
  • Beam problems for stiffmess and strength
  • Optimization of a beam for given deflection
  • Variational formulations for the eigenvalue problems: strings, bars, beams, and other elastic strucrures.
  • Optimum design of a column
  • Variable-thickness optimization of plates
  • Sufficient conditions for E-L optimum
  • Applications of sufficient conditions
  • Finite dimensional optimization--A summary and highlights
  • Numerical optimization techniques
  • Using the optimization tool-box in Matlab
  • Truss topology optimization
  • Sensitivity analysis
  • Frame topology optimization
  • Compliant mechanism design using topology optimization of trusses and frames
  • Topology optimization using continuum elements
  • Optimality criteria method
  • Shape optimization of structures
  • Applications to multi-physics problems
  • Material interpolation techniques for topology optimization

Week Dates Topics Recitations Notes Assignments
1 Jan. 3: Finite variable optimization vs. calculus of variations;
Types of optimization problems; scope of the course.
Jan. 5: No class due to the ISSS conference
Harold Kuhn's paper on Duality (Karush's work recognized)
Homework #1
2 Jan. 10: Necessary conditions for the finite variable constrained optimization problem.
Jan. 12: Concept of local and global minima
Necessary and sufficient conditions for unconstrained minimization
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Homework #2
3 Jan. 17: Karush-Kuhn-Tucker (KKT) necessary conditions
Sufficient conditions for the finite variable constrained optimization problem; bordered hessian

Jan. 19: No class due to MAMM 2012 conference.
Prof. K. Suresh's noted on finite variable optimization
Homework #2 is due on 24th Jan., 2012.
4 Jan. 24: Mathematical preliminaries for calculus of variations;
Notions of vectors space, scalar field, norm, functional, Banach space, Lebegue and Sobolve space and why we need them.
Jan. 26: No class due to Republic Day holiday.
Mathematical preliminaries for variational methods
Homework #3
5 Jan. 31: Linear and continuous functionals; Gateaux variation; Frechet differential; Fundamental lemma of calculus of variations
Feb. 2: Euler-Lagrange equations for the integrad of the simplest type, F(y,y');
variational derivative and its implication
Feb. 4, extra class for two hours: Generalization of Euler-Lagrange equations to multiple derivatives and multiple functions;
Generalization to two and three independent variables.
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6 Feb. 7: Minimization of a functional with functional type (global) constraints
A dozen problems in calculus of variations
Feb. 9: Minimization of a functional with "local" constraints
General variation (begun)
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Homework #4
7 Feb. 14: General variation continued
variable end conditions; Weierstrass-Erdmann corner conditions
Broken extremals
Feb. 16: No lecture due to travel.
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Homework #5
8 Feb. 21: First integrals of Euler-Lagrange equations; Noether's integral
Parametric form and change of variables for functionals and their Euler-Lagrange equations
Canonical form of Euler-lagrange Equations
Feb. 23: Analytical structural optimization begins
Size optimization of the stiffest bar of given weight and axial load.
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Homework #6
9 Feb. 28: Self-adjointness and weak variational form
Stiffest bar for given weight and size limits
Stiffest beam for given weight; reinforcing the procedure.
Mar. 1: Strength constraints on bars and beams
Midterm papers of previous years
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10 Mar. 6: Optimization for given deflection of bars and beams
Mar. 8: Mid-term examination
FEA notes for bars, beams, etc.
Exam!
11 Mar. 13: Truss optimization
Adjoint method (ananlytical)
Mar. 15: Sensitivity analysis for discretized systems
Adjoint vs. direct methods and their relation to the analytical (Lagrangian) method of computing sensittivities.
Beam FEM codes in Matlab
Homework #7
One-page project proposal
12 Mar. 20: Design for deflection problem; beams with discretized and continuum formulations.
Mar. 22: Hands-on computer lab session in the CoNe lab.
Beam FEM codes in Matlab
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13 Mar. 27: Stress constraints; SIMP parameterization for 2D continuum problems; glimpses of homogenization theory and its relevance to structural topology optimization
Mar. 29: No class.
Beam FEM codes in Matlab
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14 Apr. 3: Optimization for coupled electro-thermal-elastic problem; 2D continuum parameterization
Apr. 5: Hands-on computer lab session in the CoNe lab at 3 pm to 6 pm
Beam optimization code in Matlab
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15 Apr. 10: Calculus of variations and eigenvalue problems; taut string example
Apr. 12: Minimum characterization of eigenvalues problems; Rayleight quotient
maximizing buckling load of a column for given volume
Column (maximizing buckling load) optimization code in Matlab
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Finals and project presentations Apr. 25: Final examination in the CoNe laboratory at 9 am to 11 am.
May 4: Project presentations; 10 minutes per group; in the CoNe laboratory starting at 9 am.
Final examinations papers from 2005 to 2011
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