Thuy Nguyen’s Work at the 11th European Conference on Solid Mechanics

Thuy Nguyen’s recent research results on fracture mechanics have been selected for presentation at the 11th European Solid Mechanics Conference in Galway, Ireland, July 4-8, 2022. This work is part of the research collaboration between the Devinci Research Center and CEA Saclay.

Thuy Nguyen is a researcher and professor at ESILV, and a member of the Modeling Group at the De Vinci Research Center. She presented her work on brittle fracture and new resilient and lightweight metamaterials at the 11th European Solid Mechanics Conference, in Galway (Ireland), on July 4. Her contribution, titled “Effect of atomic scale discreetness in brittle fracture problem“, was highlighted in a thematic session on continuum mechanics.

The ESMC Conference, an international forum for discussion on solid mechanics

Organized by the European Mechanical Society, the European Solid Mechanics Conference is the flagship event of the solid mechanics’ community in Europe. It provides a unique forum for scientists and engineers from Europe and around the world to exchange ideas on the current state of solid mechanics, on new concepts and ideas, and to identify new research directions.

Solid mechanics is the core of engineering design in fields as diverse as mechanical engineering, civil and structural engineering and biomedical engineering.

It is a critically important element in the design and development of almost all technologies and products in these fields, such as aircraft, automobiles, buildings, bridges, and medical implants and devices. In addition, solid mechanics is a key element in developing new technologies that address the critical global sustainability, renewable energy and health challenges of our time.

A project co-led by DVRC and CEA Sarclay to better grasp the mechanics of brittle fracture

To predict where, when and how materials break is an important issue, especially in fields where safety is paramount, such as aeronautics, automobiles and construction. In a solid, the resistance to breakage is quantified by two dependent material constants: the breaking energy and the breaking tenacity. The first is proportional to the square of the second. The prediction of their values from the solid structure at the atomic scale remains unsolvable, even in the most simple situation of an ideal brittle fracture.

By studying numerical models of material failure, Thuy Nguyen and her fellow author Daniel Bonamy shed new light on this issue. In particular, they demonstrate that the fracture toughness cannot be deduced from the Griffith surface energy, as it was widely accepted until now. These results are covered in the paper “Effect of architecture disorder on the elastic response of two-dimensional lattice materials“.

Instead, its origin lies in how the displacement field, continuous on the mechanical engineering scale, connects to the discrete atomic lattice of small-scale solids. Thuy and Daniel find a solution to this connection by using the specific – singular – mathematical form taken by the field in the vicinity of the crack tip. The solution found provides a way to predict the toughness of a solid from its atomistic structure.

This work opens up new perspectives on how fracture toughness is selected and how it can be improved. Thereby, it can catalyze new research towards new architectural materials with superior structural performance through microstructure shaping: more resistant, durable, lighter, and combining other functionalities. This is the direction in which the DVRC team is now embarking in collaboration with the CEA Saclay team.