Speaker: Prof. Fengwen Wang

Abstract

Material microstructural geometry strongly dictates material properties. Novel materials with exotic properties can be achieved by carefully tailoring material geometries via different design approaches. Among them, topology optimization methods have been proven powerful tools in designing novel materials ranging from mechanical properties to acoustic and optical properties by distributing base material in material microstructures. This talk will discuss engineering material auxetic behavior, strength and stiffness response using topology and subsequent feature-based shape optimization. This first part will focus on design materials with programmable auxetic behavior under large deformation. The second part will discuss designing materials with tunable stiffness and buckling response to enhance both deformation resistance and the ultimate load-carrying capability of materials.

Biography

Fengwen Wang is a senior researcher at the Department of Mechanical Engineering, Technical University of Denmark (DTU). She obtained her Ph.D.-degree in 2012. She is an expert in large scale numerical simulations and topology optimization, including structural and material designs, and optical device designs.

Notes

• Architected materials and their optimization is a hot topic of material science. It enables to create materials that exhibit very particular and exotic functionalities (auxetic materials, negative thermal expansion coefficients, optimized strength, and others).


• Topology optimization methods are described. They rely on the definition of materials with periodic parametrized micro-structures. Using homogenization methods and finite element analysis coupled with optimization algorithms, the micro-structure parameters are optimized to match a set of desired macro-properties. The optimization can include constraints such as isotropy, bulk modulus or minimum effective stress requirements for instance.


• Examples of 2D and 3D topology optimization are presented in linear and non-linear regime with a focus on Poisson ratio optimization.


• The presentation shows how shape optimization completes topology optimization in the design of tailored yet manufacturable materials.


• The work goes beyond typical optimization in the linear small strain regime by providing very nice examples of Poisson ratio optimization in large strains, optimization of the resistance to buckling calling to Floquet-Bloch analysis and the definition of irreducible Brillouin zones for reduced computational time.

Suggested readings

• Fengwen Wang and Ole Sigmund
  Numerical investigation of stiffness and buckling response of simple and optimized infill structures.
  Structural and Multidisciplinary Optimization. Volume 61, p. 2629–2639, 2020.


• Jihong Zhu, Yu Li, Fengwen Wang and Weihong Zhang
  Shape preserving design of thermo-elastic structures considering geometrical nonlinearity.
  Structural and Multidisciplinary Optimization. Volume 61, p. 1787–1804, 2020.


• Rasmus E. Christiansen, Fengwen Wang, Ole Sigmund and Søren Stobbe
  Designing photonic topological insulators with quantum-spin-Hall edge states using topology optimization.
  Nanophotonics. Volume 8, Issue 8, 2019.


• Suna Yan, Fengwen Wang, Jun Yong and Ole Sigmund
  Topology optimization of microchannel heat sinks using a two-layer model.
  Structural and Multidisciplinary Optimization..

LMS seminars on related topics

• 25/06/2020, Prof. Paolo Celli, From patterned sheets to functional morphing structures


• 19/10/2020, Dr. Emmanuel Siéfert, Inflating to shape: from soft architectured elastomers to patterned fabric sheets