16,523 research outputs found
Topological Insulators by Topology Optimization
An acoustic topological insulator (TI) is synthesized using topology
optimization, a free material inverse design method. The TI appears
spontaneously from the optimization process without imposing requirements on
the existence of pseudo spin-1/2 states at the TI interface edge, or the Chern
number of the topological phases. The resulting TI is passive; consisting of
acoustically hard members placed in an air background and has an operational
bandwidth of 12.5\% showing high transmission. Further analysis
demonstrates confinement of more than 99\% of the total field intensity in the
TI within at most six lattice constants from the TI interface. The proposed
design hereby outperforms a reference from recent literature regarding energy
transmission, field confinement and operational bandwidth.Comment: 6 pages, 5 figure
Toplogical derivative for nonlinear magnetostatic problem
The topological derivative represents the sensitivity of a domain-dependent
functional with respect to a local perturbation of the domain and is a valuable
tool in topology optimization. Motivated by an application from electrical
engineering, we derive the topological derivative for an optimization problem
which is constrained by the quasilinear equation of two-dimensional
magnetostatics. Here, the main ingredient is to establish a sufficiently fast
decay of the variation of the direct state at scale 1 as . In order to apply the method in a bi-directional topology optimization
algorithm, we derive both the sensitivity for introducing air inside
ferromagnetic material and the sensitivity for introducing material inside an
air region. We explicitly compute the arising polarization matrices and
introduce a way to efficiently evaluate the obtained formulas. Finally, we
employ the derived formulas in a level-set based topology optimization
algorithm and apply it to the design optimization of an electric motor.Comment: 54 pages, 9 figure
- …