Ahmed Elbanna's blog

Dear all,

The Mechanics of Complex Systems Lab at University of Illinois Urbana Champaign (https://publish.illinois.edu/mcslabuiuc/)is hiring two postdoctoral researchers in the broad area of computational mechanics and its applications to environmental mechanics.

JMPS link: https://www.sciencedirect.com/science/article/pii/S0022509619304405?dgcid=raven_sd_aip_email

Arxiv link to full text: https://arxiv.org/abs/1905.08485

An Adaptive Quasi-Continuum Approach for Modeling Fracture in Networked Materials: Application to Modeling of Polymer Networks

In this paper we present a methodology for reverse engineering of trabecular bone like architectures using multi-objective topology optimization. We then investigate the mechanical properties of the resulting network structures. Specifically, we show that structures optimized according to Wolff's law alone may be stiffest but they are also fragile.

Preprint here: https://www.researchgate.net/publication/333090377_A_Novel_Hybrid_Finite...

Preprint here: https://www.researchgate.net/publication/333260238_An_Adaptive_Quasi-Con...

Draft available here

Full text here

Full text here: https://www.researchgate.net/publication/330832350_Dynamic_Rupture_Propagation_on_Fault_Planes_with_Explicit_Representation_of_Short_Branches

Periodic systems have attracted a lot of attention in science and engineering due to the existence of band gaps in their frequency spectra. Here, we study the flexural wave propagation in beams that are periodically connected in parallel and investigate how the contrast in the material and cross-sectional properties may affect the band structure of these systems and their dispersion properties.

Sacrificial bonds and hidden length mechanisms are leveraged by many biological systems for enhanced ductility and toughness. in a series of previous papers we modeled this mechanism at the level of collagen fibrils:

http://publish.illinois.edu/mcslabuiuc/files/2017/12/2013-Elbanna-Carlson.pdf

http://publish.illinois.edu/mcslabuiuc/files/2017/12/2013-Lieou-Elbanna-Carlson.pdf

Abstract: Shear banding is widely observed in natural fault zones as well as in laboratory experiments on granular materials. Understanding the dynamics of strain localization under different loading conditions is essential for quantifying strength evolution of fault gouge and energy partitioning during earthquakes and characterizing rheological transitions and fault zone structure changes. To that end, we develop a physics-based continuum model for strain localization in sheared granular materials.

On the Role of the Plaque Porous Structure in Mussel Adhesion: Implications for Adhesion Control Using Bulk Patterning

Ahmed Ghareeb and Ahmed Elbanna -- Journal of Applied Mechanics (2018)

Mechanical Response of Two Dimensional Polymer Networks: Role of Topology, Rate Dependence, and Damage Accumulation

In this paper we highlight several interesting phenomena that may emerge from coupling simple elastic systems like 1d bars. While in compostes we usually focus on wave propagation normal to the stratification direction (composite layers are coupled in series), here we show that extreme attenuation at multiple frequencies may emerge in linear systems that are coupled transversaly. We also introduce a simple device that act as a chopper for mechanical signals.

http://www.nature.com/articles/s41598-017-16364-8

Dear Colleagues,

We cordially invite you to submit an abstract to 1702 Computational Geophysics; a minisymposium that will take place as part of the upcoming 13th World Congress on Computational Mechanics (New York July 22- July 27, 2018) : http://www.wccm2018.org/MS_1702  

Abstract Deadline: Dec 31st, 2017

The Finite Difference (FD) and the Spectral Boundary Integral (SBI) methods have been used extensively to model spontaneously propagating shear cracks in a variety of engineering and geophysical applications. In this paper, we propose a new modeling approach, in which these two methods are combined through consistent exchange of boundary tractions and displacements. Benefiting from the flexibility of FD and the efficiency of spectral boundary integral methods, the proposed hybrid scheme will solve a wide range of problems in a computationally efficient way.

Shear banding and stick-slip instabilities have been long observed in sheared granular materials. Yet, their microscopic underpinnings, interdependencies and variability under different loading conditions have not been fully explored. Here, we use a non-equilibrium thermodynamics model, the Shear Transformation Zone theory, to investigate the dynamics of strain localization and its connection to stability of sliding in sheared, dry, granular materials. We consider frictional and frictionless grains as well as presence and absence of acoustic vibrations.

A wide range of engineered and natural composites exhibit a layered architecture whereby individual building blocks are assembled layer by layer using cohesive interfaces. We present a novel mechanism for evolving acoustic band gap structure in a model system of these composites through patterning the microstructure in a way that triggers non-planar interfacial deformations between the layers as they are stretched.

Dear Colleagues,

We would like to invite you to consider submitting abstracts to the following minisymposium taking place as part of the Soceity of Engineering Sciences meeting to be hosted by the University of Maryland (October 2-5, 2016)

D-9 :Friction, Fracture and damage (http://ses2016.org/symposium-d-9-friction-fracture-and-damage/)

Dear Colleagues,

We would like to invite you to consider submitting abstracts to the following minisymposium taking place as part of the Soceity of Engineering Sciences meeting to be hosted by the University of Maryland (October 4-7, 2016)

D-9 :Friction, Fracture and damage (http://ses2016.org/symposium-d-9-friction-fracture-and-damage/)

Friction and deformation in granular fault gouge are among various dynamic interactions associated with seismic phenomena that have important implications for slip mechanisms on earthquake faults. To this end, we propose a mechanistic model of granular fault gouge subject to acoustic vibrations and shear deformation. The grain-scale dynamics is described by the Shear-Transformation-Zone theory of granular flow, which accounts for irreversible plastic deformation in terms of flow defects whose density is governed by an effective temperature.