Seminário

Illuminating the effects of grain shape and size on granular material behavior

Sala 1.3.14, Ciências ULisboa

Por Emilien Azéma (Laboratoire de Mécanique et Génie Civil - LMGC, Université de Montpellier, France).

For centuries, human civilizations have used, handled, transported and transformed granular materials, such as sand, rock, and powder, in a variety of applications, including civil construction, powder compaction, pharmacy.... As a general observation, in all fields where matter is divided into a “granular” form, technological innovation has been supported by a semi-empirical approach. The solid-like, fluid-like and transition to jamming properties of granular materials have been a subject of extensive investigation since decades in different scientific communities which now benefits from a rich experimental background and various continuum or micro-mechanical models often associated with finite-element and/or discrete-element calculations. Nevertheless, significant decline in natural resources and an increase in human activities challenge the way these materials are currently used in human activities. In order to improve predictions and optimizing materials, new approaches must be developed that have to incorporate increasingly realistic characteristics to highlight the key processes at the grain and contact scales. Regardless of the application, granular media are characterized by generic features such as their discrete and disordered microstructure, the predominance of geometric and kinematic constraints and the dissipative character of interactions. But, for each application, this generic character comes up against specific characteristics such as the shape of the grains, their size dispersity (polydispersity), complex interactions (cohesive, capillary, electrical, fluid phase,...). All these elements of complexity are rarely captured by the most common simulation techniques. In order to obtain a clear and precise picture of the complex behavior of real granular materials, it is essential to understand and quantify each of the above-mentioned effects. In this seminar, we will specifically discuss the effect of grain shape and size on the rheology and microstructures of compressed or sheared grain assemblies. Our numerical results highlight specific non-intuitive behaviors, including the non-linear variation of the strength as a function of the packing fraction of the assemblies when the grain shapes deviate from that of a sphere or when the polydispersity in grain size increases. At the microscopic scale, we explain these behaviors from subtle compensation between the contact networks orientations, force anisotropies, and friction mobilization. These analyses are a first step towards a better understanding of increasingly realistic combined effects on the rheology of divided materials.

10h00-11h00
CFTC - Centro de Física Teórica e Computacional
Logótipos Ciências ULisboa e C-Academy, títulos dos cursos

Um programa de formação avançada em Cibersegurança para a administração pública e o setor privado desenvolvido pelo Centro Nacional de Cibersegurança, no âmbito do Plano de Recuperação e Resiliência.

Logótipos Ciências ULisboa e C-Academy, títulos dos cursos

Um programa de formação avançada em Cibersegurança para a administração pública e o setor privado desenvolvido pelo Centro Nacional de Cibersegurança, no âmbito do Plano de Recuperação e Resiliência.

Logótipo do evento, sobre um fundo branco

Um evento de reunião da comunidade nacional nas diversas vertentes da informática, com a ambição de ser o fórum de eleição para a divulgação, discussão e reconhecimento de trabalhos científicos.

Imagem do evento

Extended enrolement date until July 12th.

Logótipo do Workshop

A participação na 3.ª edição do Workshop é gratuita, mediante inscrição prévia.

Are you ready for this year's edition?

Imagem do evento - título, local e data do evento

Investigação Ecológica ao Serviço da Conservação

A leading venue for presenting and discussing the latest research, industrial practice and innovations in dependable and secure computing.