Degenerate Torque Materials for Perfect Cloaking in Elastic Media
Abstract
Major Goals: The central object of this proposal is the study of cloaking materials within the framework of a new class of elastic materials termed Degenerate Torque Materials (DTMs) and characterized as materials admitting a set of collapse mechanisms and torque-induced non-symmetric stress states. The research will establish a theoretical framework for the modelling of DTMs and will tackle the inverse problem of design of specific DTMs targeting particular macroscopic constitutive parameters, typical of those required by elastic cloaks. The necessity in elastic cloaking of a material with engineered collapse mechanisms and torque distributions, as well as modern advances in additive manufacturing technology, all encourage the use of truss- or lattice-based design paradigms. The research will accordingly explore paths towards the design and fabrication as well as dynamic modeling and homogenization of specific degenerate mechanical trusses and lattices admitting collapse mechanisms and exhibiting aptitude for the support of torque densities and non-symmetric stresses. Accomplishments: Elastic cloaking has been a longstanding open problem in the area of transformation-based wave control. While theory and applications progressed smoothly in transformation optics and acoustics, the multitude of coupled propagated modes (e.g., shear and pressure) in elasticity introduced an unparalleled complication. Indeed, it turns out that the application of the transformation method necessitates the use of so-far lacking materials that exhibit asymmetric stresses as well as specific stressless deformation modes. In first two years of this funded project, we obtained the first lattice-based metamaterials that fulfil the requirements of the transformation method. An invisibility cloak in fully coupled 2D elasticity was then designed by spatially grading these metamaterials.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 22, 2022
- Accession Number
- AD1210566
Entities
People
- Guoliang Huang
Organizations
- University of Missouri