This is page xi Printer: Opaque this List of Figures P.1 P.2 An optimal conducting composite structure . . . . . . . . xvi Anisotropy of an optimal elastic structure . . . . . . . . . xvii 1.1 1.2 1.3 1.4 1.5 Oscillating minimizing sequence . . . . . . . . . . . . Definition of convexity . . . . . . . . . . . . . . . . . Weierstrass variation . . . . . . . . . . . . . . . . . . Oscillating minimizing sequence . . . . . . . . . . . . Convexification of the Lagrangian and the minimizer . . . . . 5 8 13 15 25 2.1 2.2 2.3 The refraction of the current and the field . . . . . . . . . The fields and the currents in a laminate . . . . . . . . . . The field in coated circles . . . . . . . . . . . . . . . . . . . 40 52 55 3.1 3.2 3.3 3.4 3.5 Various limits of materials layouts. . . . Conservation property of G-closure . . . G-closure in two dimensions . . . . . . . Domain of attainability, two dimensions Domain of attainability, three dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 71 73 75 76 4.1 4.2 4.3 4.4 4.5 4.6 Problem of the best conductivity of a domain . . Variation in a strip . . . . . . . . . . . . . . . . . Forbidden interval . . . . . . . . . . . . . . . . . . The constitutive relations in the optimal medium Convex nonsmooth Lagrangian . . . . . . . . . . The constitutive equation for the optimal medium . . . . . . . . . . . . . . . . . . . . . . . . . 82 . 94 . 96 . 98 . 104 . 106 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii List of Figures 4.7 4.8 4.9 4.10 The optimal annular conductors . . . . . . . Bar of the maximal torsion stiffness . . . . . Multiwell Lagrangians . . . . . . . . . . . . Dependence of the volume M2 on the cost γ2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 111 112 114 5.1 5.2 5.3 5.4 5.5 5.6 The local problem . . . . . . . . . . . An optimally conducting cylinder . . Draft of the fields in the thermolens . Draft of the optimal thermolens . . . The fields in the optimal domain . . Optimal project, conducting domain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 135 137 137 138 138 6.1 6.2 A strong local perturbation of a potential . . . . . . . . . . 152 To the Weierstrass variation . . . . . . . . . . . . . . . . . 153 7.1 7.2 7.3 7.4 7.5 A second rank laminate . . . . . . . . . Constructing an infinite-rank laminate Matrix laminates . . . . . . . . . . . . T-structure . . . . . . . . . . . . . . . . Multicoated matrix laminates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 186 190 197 198 9.1 9.2 9.3 9.4 Optimality conditions: A family of trial inclusions . Permitted regions of fields in an optimal composite The fields in coated circles . . . . . . . . . . . . . . The fields in matrix laminates . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245 249 254 255 10.1 10.2 10.3 The scheme of bounding of a Gm -closure . . . . . . . . . . 264 Construction of L-closure . . . . . . . . . . . . . . . . . . . 272 The L-closure of conducting materials, 2D . . . . . . . . . 276 11.1 11.2 11.3 11.4 11.5 11.6 The Gm -closure in two dimensions . . . . . . . . . . . . The Gm -closure in three dimensions . . . . . . . . . . . G-closure in three dimensions . . . . . . . . . . . . . . Coupling: The isotropic component of the Gm -closure. Coupling: Range of the anisotropic conductivities . . . Geometry of the “secured spheres” . . . . . . . . . . . . . . . . . . . . . . . 283 288 291 304 306 307 12.1 12.2 12.3 12.4 12.5 12.6 12.7 12.8 12.9 Range of three-material composites . . . . . . . . . . . An extremal anisotropic three-component structure . . Isotropic optimal multicomponent structures . . . . . . Optimal three-component structures. Case I . . . . . . Optimal three-component structures. Case II . . . . . . Compatible composites from four materials. The fields Compatible composites from four materials. Geometry Permitted regions, based on single variations . . . . . . Scheme of a composite variation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311 312 318 319 321 323 324 327 328 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . List of Figures xiii 12.10 12.11 12.12 12.13 12.14 12.15 Permitted region V2 , based on composite variations Permitted region V1 based on composite variations The permitted regions, γ = γ1 . . . . . . . . . . . . The permitted regions, γ ∈ (γ1 , γ2 ) . . . . . . . . The permitted regions, γ = γ2 . . . . . . . . . . . . The permitted regions, γ 6∈ [γ1 , γ2 ] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332 333 336 336 337 337 14.1 14.2 14.3 14.4 Stresses, applied to a unit square . . . . . . . . Orthogonal matrix laminate of the second rank Representation of tensors t ⊗ t . . . . . . . . . Herringbone structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361 383 388 390 15.1 15.2 15.3 15.4 15.5 15.6 15.7 15.8 15.9 15.10 Bounds on the stored energy . . . . . . . . . . . . . Structures of extremal stiffness . . . . . . . . . . . . The upper WL and lower Wp bounds of the energy The quasiconvex envelope . . . . . . . . . . . . . . Optimal periodic structures . . . . . . . . . . . . . Optimal cavities: Elongated periodicity cells . . . . Why does the optimal cavity have corners? . . . . . Energy outside of the optimal cavity . . . . . . . . The more cavities, the better . . . . . . . . . . . . . Optimal cavities, dependence on the loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398 400 401 403 415 415 417 418 419 419 16.1 16.3 16.4 16.5 16.6 Hashin–Shtrikman bounds, Walpole points, and translation bounds: Well-ordered materials . . . . . . . . . . . . . . . Hashin–Shtrikman points, Walpole bounds, and translation bounds: Badly ordered materials . . . . . . . . . . . . . . . Hexagonal structures by Sigmund . . . . . . . . . . . . . . An optimal polycrystal, differential scheme . . . . . . . . . Convergence of the family of bounds . . . . . . . . . . . . Optimal fractal structure . . . . . . . . . . . . . . . . . . . 428 430 454 456 458 17.1 17.2 17.3 17.4 17.5 17.6 17.7 17.8 A third-rank laminate . . . . . . . . . . . . . . . Optimal console, piece-wise constant properties An optimal cylindrical shell . . . . . . . . . . . Example of an unstable design . . . . . . . . . . The optimal beam under the “worst” loading . Optimal structure under multiple loading . . . . Nonsmooth minimum . . . . . . . . . . . . . . . Optimal structure of a wheel . . . . . . . . . . . 467 473 476 481 485 487 491 494 16.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 428