research

https://doi.org/10.1038/s41467-019-08891-x We report the discovery of structural coloration emanating in precise register with expanded pigmented chromatocytes.

Fatigue of hydrogels

Ruobing Bai (1,2), Zhigang Suo (1)

(1) John A. Paulson School of Engineering and Applied Sciences, Kavli Institute for Bionano Science and Technology, Harvard University

(2) Department of Mechanical and Civil Engineering, California Institute of Technology

http://dx.doi.org/10.1080/14786435.2019.1582850

Abstract

Published in Physcal Review Letters: https://doi.org/10.1103/PhysRevLett.122.045502. Many materials are anisotropic. However, there is no widely accepted measure for characterizing the degree of elastic anisotropy. Here, assuming that the limiting case of extreme anisotropy should possess a positive semidefinite stiffness matrix, we propose three criteria to evaluate measures of anisotropy and show that the existing measures in the literature do not satisfy all of the proposed criteria.

https://doi.org/10.1002/adma.201805665 Computational modeling and simulations play an integral role in the bottom‐up design and characterization of graph‐n‐yne materials. Here, the state of the art in modeling α‐, β‐, γ‐, δ‐, and 6,6,12‐graphyne nanosheets for synthesizing graph‐2‐yne materials and 3D architectures thereof is discussed.

https://doi.org/10.1038/s41467-019-08813-x We report a transfer approach using paraffin as a support layer, whose thermal properties, low chemical reactivity and non-covalent affinity to graphene enable transfer of wrinkle-reduced and clean large-area graphene.

We are looking for a candidate with a Ph.D. degree to study fracture problems in bimetallic pipelines,  API X65 internally clad with alloy 625. The project has direct application to offshore exploration in Brazil deepwater fields. The project is going to be funded by the Petrobras company. The chosen candidate will develop a parametric model to model the welded joint of this type of pipes using python/Abaqus, being the numerical model as close as possible to the real geometry.

We have published a paper called "Micromechanical model for prediction of the fatigue limit for unidirectional fibre composites" in Mechanics of Materials. See the link here.

I hope some of you will find our recent paper in the Journal of the Mechanics and Physics of Solids interesting. The Abaqus user element (UEL) subroutine developed to implement strain gradient plasticity theories with energetic and dissipative higher order stresses (Gudmundson 2004, Fleck and Willis 2009) can be downloaded from www.empaneda.com/codes

The role of plastic strain gradients in the crack growth resistance of metals

Emilio Martínez-Pañeda, Vikram S. Deshpande, Christian F. Niordson, Norman A. Fleck

Published in Phys. Rev. B: https://journals.aps.org/prb/abstract/10.1103/PhysRevB.97.184305

Published in Nanoscale and Microscale Thermophysical Engineering: https://www.tandfonline.com/doi/full/10.1080/15567265.2019.1576816

Wenjie Xia, Xin Qin, Yao Zhang, Rober Sinko, Sinan Keten

Macromolecules (2018), https://pubs.acs.org/doi/abs/10.1021/acs.macromol.8b02243

Wenjie Xia, Fernando Vargas-Lara, Sinan Keten, Jack F. Douglas

ACS Nano (2018), https://pubs.acs.org/doi/abs/10.1021/acsnano.8b00524

Liu, M., Wu, J., Gan, Y., Hanaor, D. A. H., & Chen, C. Q. International Journal of Solids and Structures, 2019, 162: 36-44.  https://www.sciencedirect.com/science/article/pii/S0020768318304827

Abstract 

Aalto University School of Engineering in Finland invites application for 

TWO DOCTORAL STUDENT POSITIONS IN ICE MECHANICS

The positions are in the research group of Marine and Arctic Technology.

Applications are invited for PhD positions at the Algorithms in Medicine and Neuro-Technology Lab (AIMAN Lab) in the Department of Mechanical Engineering at George Mason University, Fairfax, VA.

Research
The AIMAN Lab pursues fundamental breakthroughs in biomedical cyber-physical systems. The lab’s primary research focuses on application of mathematical modeling, controls and estimation theory, and machine learning in health information technology including decision support and automated care systems, with the intention of improving the quality of healthcare, as well as brain-computer interfaces to bring neuro-enhancements to the daily consumer.

Application
Interested researchers with passion in digital healthcare and neuroscience are encouraged to send their CV to Dr. Ramin Bighamian at rbighami@gmu.edu.

Qualification
Experience in controls engineering, estimation theory, machine learning, MATLAB
A Master's degree in mechanical engineering, electrical engineering, or other related disciplines.

Solving incompressible elasticity has been quite challenging numerically. The conventional approach for handling incompressibility is the so-called penalty method. A volumetric energy term enters into the strain energy and penalizes the volumetric deformation. One straightforward issue is that the penalty parameter goes directly into the tangent matrix. The bigger the penalty parameter, the worse the condition number of the matrix. This is really a manifestation of the ill-posedness of theories based on the Helmholtz free energy, in my opinion [3].

Context
As part of a collaborative project between different faculties of the University of Liege (Belgium), there is an open position to develop and validate numerical models for shape memory composite.

PhD or Post Doc opportunity
The project will be supervised by Prof. L. Noels of ULg (http://www.ltas-cm3.ulg.ac.be/). The position is that of either a PhD student or a Post-Doc for renewable periods of 12 months starting immediately.

Dear colleagues,

I would like to share with you our latest paper focusing on the fracture of hydrogels of complex rheology.

Title: Tearing a hydrogel of complex rheology

Authors: Ruobing Bai, Baohong Chen, Jiawei Yang, Zhigang Suo*

Abstract:

Journal of The Royal Society Interface 16(151), February 2019.    DOI: 10.1098/rsif.2018.0738

Michele Ciavarella Junki Joe Junki Joe Antonio Papangelo James Richard Barber

Just published in Journal of the Royal Society Interface

Ciavarella M, Joe J, Papangelo A, Barber JR. 2019 The role of adhesion in contact mechanics. J. R. Soc. Interface 16: 20180738. http://dx.doi.org/10.1098/rsif.2018.0738

Abstract

<p>Applications are invited for PhD positions at the Algorithms in Medicine and Neuro-Technology Lab (AIMAN Lab) in the Department of Mechanical Engineering at George Mason University, Fairfax, VA. "Research" The AIMAN Lab pursues fundamental breakthroughs in biomedical cyber-physical systems.