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Mike Ciavarella's picture

Mean stress effect on Gaßner curves interpreted as shifted Wöhler curves

A criterion for the mean stress effect correction in the shift factor approach for variable amplitude life prediction is presented for both smooth and notched specimens. The criterion is applied to the simple idea proposed by the authors in a previous note that Gaßner curves can be interpreted as shifted Wöhler curves. The mean stress correction used has been proposed by Smith, Watson and Topper and, more in general, by Walker.

Postdoc Position in flexible skins for morphing wings

A postdoc in the area of flexible skin for morphing wings is available at Khalifa University, UAE. 

A 3D phase field dislocation dynamics model for body-centered cubic crystals

This is the preprint of an article that will appear in Computational Materials Science (doi.org/10.1016/j.commatsci.2019.109217)

A 3D phase field dislocation dynamics model for body-centered cubic crystals

Zhengwei Li's picture

New method to fabricate 3D curvy electronics

We report a manufacturing technology, called conformal additive stamp (CAS) printing and show that it can be used to reliably manufacture electronic devices with 3D shapes. Our CAS printing approach employs a pneumatically inflated elastomeric balloon as a conformal stamping medium to pick up pre-fabricated electronic devices and print them onto 3D surfaces to create devices with curvy shapes including electrically small antennas, hemispherical solar cells and smart contact lenses.

SwarnavaGhosh's picture

Symmetry-adapted real-space density functional theory for large nanotubes and bending deformations of thin sheets

Dear Colleagues,

Here is our recently published article on Symmetry-adapted real-space density functional theory for large nanotubes and bending deformations of thin sheets

Title: Symmetry-adapted real-space density functional theory for cylindrical geometries: Application to large group-IV nanotubes

 Authors: Swarnava Ghosh, Amartya S. Banerjee, Phanish Suryanarayana*

Concise summary

Arash_Yavari's picture

Applications of Algebraic Topology in Elasticity

In this book chapter we discuss some applications of algebraic topology in elasticity. This includes the necessary and sufficient compatibility equations of nonlinear elasticity for non-simply-connected bodies when the ambient space is Euclidean. Algebraic topology is the natural tool to understand the topological obstructions to compatibility for both the deformation gradient F and the right Cauchy-Green strain C. We will investigate the relevance of homology, cohomology, and homotopy groups in elasticity.

Zhaohe Dai's picture

Bending of Multilayer van der Waals Materials

Dear colleagues, I'd like to share our recent work on blister testing of multilayer 2D materials that gives a direct measurement of Young's modulus and bending rigidity of a multilayer (~10-70 layers). Materials involved include graphene, MoS2, and hBN.

D.Rittel's picture

About Mechanics-Materials and Dentistry of dental implants

Dental implants are increasingly being placed for edentulous patients worldwide. While the clinical aspects of the implants are extensively investigated, engineering considerations of the implant as a functional structure subjected to ill-defined boundary conditions are less considered. A recent trend is to consider all ceramic implants as an alternative to the classical titanium-based implants.

Shuozhi Xu's picture

Uniaxial deformation of tungsten nanopillars/nanowires/nanotubes: Atomistic and coarse-grained atomistic simulations

Dear Colleague,

In the last two years, we published six papers on uniaxial deformation of tungsten nanopillars/nanowires/nanotubes using atomistic and coarse-grained atomistic simulations:

Jinxiong Zhou's picture

Snap-back induced hysteresis in an elastic mechanical metamaterial under tension

We combine experiment and finite element simulation and come up with a design of a mechanical metamaterial which demonstrates snap-back induced hysteresis and energy dissipation. The resultant is an elastic system that can be used reversibly for many times. The underlying mechanism of existence of hysteresis and the physics of snap-back induced elastic instability is unveiled. Our results open an avenue for design and implementation of recoverable energy dissipation devices by harnessing mechanical instability.

Antonio Papangelo's picture

Citation metrics author database for many scientific fields

Citation metrics are widely used and misused.  Ioannidis and co-authors have created a publicly available database of 100,000 top scientists that provides standardized information on citations, h-index, coauthorship-adjusted hm-index, citations to papers in different authorship positions, and a composite indicator.

Arash_Yavari's picture

Compatible-Strain Mixed Finite Element Methods for 3D Compressible and Incompressible Nonlinear Elasticity

A new family of mixed finite element methods --- compatible-strain mixed finite element methods (CSFEMs) --- are introduced for three-dimensional compressible and incompressible nonlinear elasticity. A Hu-Washizu-type functional is extremized in order to obtain a mixed formulation for nonlinear elasticity. The independent fields of the mixed formulations are the displacement, the displacement gradient, and the first Piola-Kirchhoff stress. A pressure-like field is also introduced in the case of incompressible elasticity.

sairajatm's picture

Finite Element Approximation of Finite Deformation Dislocation Mechanics

We develop and demonstrate the first general computational tool for finite deformation static and dynamic dislocation mechanics. A finite element formulation of finite deformation (Mesoscale) Field Dislocation Mechanics theory is presented. The model is a minimal enhancement of classical crystal/J_2 plasticity that fundamentally accounts for polar/excess dislocations at the mesoscale. It has the ability to compute the static and dynamic finite deformation stress fields of arbitrary (evolving) dislocation distributions in finite bodies of arbitrary shape and elastic anisotropy under general boundary conditions. This capability is used to present a comparison of the static stress fields, at finite and small deformations, for screw and edge dislocations, revealing heretofore unexpected differences. The computational framework is verified against the sharply contrasting predictions of geometrically linear and nonlinear theories for the stress field of a spatially homogeneous dislocation distribution in the body, as well as against other exact results of the theory. Verification tests of the time-dependent numerics are also presented. Size effects in crystal and isotropic versions of the theory are shown to be a natural consequence of the model and are validated against available experimental data. With inertial effects incorporated, the development of an (asymmetric) propagating Mach cone is demonstrated in the finite deformation theory when a dislocation moves at speeds greater than the linear elastic shear wave speed of the material.

 

Paper can be found at link Finite_Deformation_Dislocation_Mechanics.

 

 

 

Opening for new Ph.D. students in the Design & Uncertainty Quantification group, The University of Iowa.

The Design & Uncertainty Quantification group at The University of Iowa, led by Professor Sharif Rahman, is looking for new Ph.D. students, who are capable of and interested in performing high-quality research on uncertainty quantification and stochastic design optimization. The research, supported by U.S. National Science Foundation, requires building a solid mathematical foundation, devising efficient numerical algorithms, and developing practical computational tools, all associated with stochastic analysis and design of complex materials and structures.

Mike Ciavarella's picture

Universal features in "stickiness" criteria for soft adhesion with rough surfaces

A very interesting recent paper by Dalvi et al. has demonstrated convincingly with adhesion experiments of a soft material with a hard rough material that the simple energy idea of Persson and Tosatti works reasonably well, namely the reduction in apparent work of adhesion is equal to the energy required to achieve conformal contact. We demonstrate here that, in terms of a stickiness criterion, this is extremely close to a criterion we derive from BAM (Bearing Area Model) of Ciavarella, and not very far from that of Violano et al.

Bin Liu's picture

Why are most 2D lattices hexagonal? The stability of 2D lattices predicted by a simple mechanics model

Published in Extreme Mechanics Letters: https://doi.org/10.1016/j.eml.2019.100507. For more than half a century, physicists rejected the existence of two-dimensional (2D) materials since they theoretically underestimated the stability. However, the discovery of one-atom-thick graphene proved the inapplicability of this theory.

Ramathasan Thevamaran's picture

Asymmetric acoustic energy transport in non-Hermitian metamaterials

One of our studies on linear and nonlinear non-Hermitian metamaterials has been published on the recent special issue of the Journal of the Acoustical Society of America: Non-Reciprocal and Topological Wave Phenomena in Acoustics.

Abstract

KevinGE's picture

Submission Invitation to Special Issue of Polymers

The special issue “Design and Manufacturing of Shape Memory Polymers and Active Structures” of Polymers is now inviting submission. If you have any suitable manuscript, please consider this special issue. Feel free to contact me through geq@sustech.edu, if you have any questions. Thank you all for your support!

 

 

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