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Characterization of fracture in topology-optimized bio-inspired 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.

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Dynamics of periodically coupled parallel flexural elements: towards the modular design of metamaterial beams

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.

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Extreme enhancement of interfacial adhesion by bulk patterning of sacrificial cuts

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

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Strain Localization in Dry Sheared Fault Gouge: A Compactivity based approach

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.

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Mechanics and Mussel adhesion: How bulk porosity may help things stick better

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)

 

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Modeling rate dependent damage in polymer networks with sacrificial bonds

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

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Can you "chop" a mechanical wave?

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

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Invitation to 13th World Congress on Computational Mechanics (MS1702: Computational Geophysics)

 

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

 

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USNC-TAM: Minisymposium on Friction, Fracture, and Damage

Dear Colleagues,

We cordially invite you to submit an abstract to MS 335: Friction, Fracture, and Damage; a minisymposium that will take place as part of the upcoming US National Congress on Theoretical and Applied Mechanics (Chicago, IL June 4th -9 th 2018). Abstract Deadline: Nov 10th :http://sites.northwestern.edu/usnctam2018/

Ahmed Elbanna, University of Illinois Urbana Champaign

Krishnaswamy Ravi-Chandar, University of Texas at Austin

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A new hybrid numerical scheme for modeling elastodynamics in unbounded media with near-source heterogeneities

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.

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Localization and instability in sheared granular materials: Role of friction and vibration

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.

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Modulating elastic band gap structure in layered soft composites using sacrificial interfaces

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.

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Modulating elastic band gap structure in layered soft composites using sacrificial interfaces

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.

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[Call for Abstracts] SES minisymposium on 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 2-5, 2016)

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

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[Call for Abstracts] SES minisymposium on 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/)

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Dynamic friction in sheared fault gouge: implications of acoustic vibration on triggering and slow slip†

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.

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Transfer printing enabled soft composite films for tunable surface topography

Transfer printing, an emerging manufacturing technique for heterogeneous material integration, is combined with the unique mechanics of soft composite films to realize a responsive surface for tunable topography in this work. Soft composite films are fabricated by transfer printing thin silicon ribbons on elastomeric films in a staggered manner. The corrugation formation in soft composite films requires a well-organized spatial distribution of the silicon ribbons which is enabled by transfer printing processes developed here.

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Journal Club Theme of January 2016: Extreme Mechanics on the Surface of our Planet

Our experience with earthquakes is that they are violent events that take a heavy toll on our societies through life and property losses. However, earthquakes present us with some of the most challenging questions in mechanics. By better understanding the nucleation and propagation dynamics of earthquakes, we may make progress towards minimizing their negative impact. Insights from mechanics may help in the development of better seismic hazard models as well as in the construction of more efficient earthquake early warning systems.

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