Xueyan Chen : Nodal design of lattice mechanical metamaterials

Abstract : Joints or nodes with complex geometrical configuration at the connection between rods are commonly found in lattice materials. The existence of nodes definitely has a determinant impact on the mechanical properties of the lattice materials. The main focus of this thesis is elementary cubic truss lattices. The first innovation that is proposed is an analytical model to identify the effect of nodes and bending on the compressive response of FCC lattices. Based on the obtained result, lightweight ultra-strong open-form BCC shellular and closed-form SC tubular mechanical materials are presented, for supporting load and absorbing energy. The choice of nodes provides one with a possibility to control the elastic isotropy of lattice materials. We propose a new class of light-weight elastic isotropic bending-dominated truss lattice by replacing the inner node of the BCC lattice with a SC lattice. Numerical simulations reveal that the proposed lattices not only exhibit elastic isotropy but also a nearly isotropic nonlinear response. We also propose a new class of isotropic and reusable cork-like metamaterial that is designed from an hybrid truss-lattice material with complex node connection. The metamaterial shows an isotropic Poisson's ratio close to zero. It can recover 96.6% of its original shape after a compressional test exceeding 20% strain. Uniaxial compression tests are performed to confirm the designs in all cases.

Jury Composition : 

Vincent LAUDE, Directeur de recherche, Université Bourgogne Franche-Comté, PhD CoDirector

Claude BOUTIN, Professeur, Université de Lyon,Reporter

Corentin COULAIS, Assistant professor, Universiteit van Amsterdam, Netherlands, Reporter

Muamer KADIC, Maître de conférences, Université Bourgogne Franche-Comté            

Huifeng TAN, Professeur, Harbin University of Technology, PhD Codirector

Gengkai HU, Professeur, Beijing Institute of Technology, Reviewer

Yuesheng WANG, Professeur, Tianjin University, Reviewer

Localization :  Harbin Institute of Technology 92 Xidazhi Street 150001 Harbin, Chine - salle Salle 313