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Parag Tandaiya's picture

Wallner lines, crack velocity and mechanisms of fracture in a brittle bulk metallic glass

A few years ago, we observed Wallner Lines on the fracture surface of a brittle Bulk Metallic Glass and explained the process of formation of nanocorrugations on the fracture surface.

We published our research in Acta Materialia in the paper: 'Wallner lines, crack velocity and mechanisms of fracture in a brittle bulk metallic glass'.

Parag Tandaiya's picture

On the mechanism and the length scales involved in the ductile fracture of a bulk metallic glass

A few years ago we published a paper in Acta Materialia elucidating the mechanism and length scales in the ductile fracture of bulk metallic glass through experiments and finite element simulations.

The link to the paper is here: 'On the mechanism and the length scales involved in the ductile fracture of a bulk metallic glass'.

I hope you enjoy reading the paper and find it useful in your research.

Parag Tandaiya's picture

Fracture of notched ductile bulk metallic glass bars subjected to tension-torsion: experiments and simulations

There is a shortage of literature on mode III fracture behaviour of bulk metallic glasses.

In our following research paper published in Acta Materialia, we report our experiments and three-dimensional elasto-plastic finite element simulations of tension-torsion loading on notched ductile bulk metallic glass bars.

It is found that fracture toughness of this BMG is lowest in mode II among all three fracture modes.

Parag Tandaiya's picture

Temperature-dependence of mode I fracture toughness of a bulk metallic glass

Bulk Metallic Glasses were found to exhibit an intermediate temperature minimum in ductility. Does it also lead to an intermediate temperature minimum in fracture toughness?

Parag Tandaiya's picture

Mechanisms of compressive deformation and failure of porous bulk metallic glasses

Porous Bulk Metallic Glasses have been invented by researchers to mitigate catastrophic failure in monolithic Bulk Metallic Glasses which are susceptible to intense strain localization into shear bands.

Valeriy Buryachenko's picture

Nonlocal Micromechanics of Composites of both Random and Periodic Structures (Background, Opportunities and Prospects)

An extended abstract dedicated to nonlocal (in the sense of either Eringen or Silling) micromechanics is attached. It can’t be considered as a review in any sense. It is just a personal vision on a new area of micromechanics, in particularly based on the author’s publications (references on hundreds related papers can be found in the referred publications). The style of the abstract is plausible rather than rigorous that willfully used by the author just for initiation of discussions in the new prospective area of micromechanics.

Ajeet Kumar's picture

Microscopic definition of internal force, moment and associated stiffnesses in one-dimensional nanostructures at finite temperature

We present a one-dimensional variant of the Irving-Kirkwood-Noll procedure to derive microscopic expressions of internal contact force and moment in one-dimensional nanostructures. We show that these expressions must contain both the potential and kinetic parts: just the potential part does not yield meaningful continuum results. We further specialize these expressions for helically repeating one-dimensional nanostructures for their extension, torsion and bending deformation. As the Irving-Kirkwood-Noll procedure does not yield expressions of stiffnesses, we resort to a thermodynamic equilibrium approach to first obtain the Helmholtz free energy of the supercell of helically repeating nanostructures. We then obtain expressions of axial force, twisting moment, bending moment and the associated stiffnesses by taking the first and second derivatives of the Helmholtz free energy with respect to conjugate strain measures. The derived expressions are used in finite temperature molecular dynamics simulation to study extension, torsion and bending of single-walled carbon nanotubes and their buckling.
The article will soon appear in the Mathematics and Mechanics of Solids. The same can be accessed at the following link: https://www.researchgate.net/publication/337873624_Microscopic_definitio...

Post-Doctoral Position in Modeling of Thermal Transport in Crystalline Solids

The Materials Theory Group at the School of Materials Engineering of Purdue University has a post-doctoral opening in the area of modeling of thermal transport in crystalline solids. The postdoc will use Boltzmann Transport Equation approach to investigate the phonon and electron thermal transport in crystalline solids with defects. Applicants with closely related theory background in physics, materials science, mechanical engineering, or other majors are encouraged to apply. The ideal candidate is one who is strongly interested in the fundamental concepts of thermal transport and related computational modeling, and must have excellent programming skills. To apply, please send a curriculum vita with list of publications and the names and contact information of two references to Professor Anter El-Azab (aelazab@purdue.edu). The cover letter should explain the relevance of the applicant background to the postdoc research topic above. This position is part of the DOE funded Energy Frontiers Research Center for Thermal Energy Transport under Irradiation (TETI), and the postdoc is expected to collaborate with a large team of theorists and experimentalists. The position is available now and will remain open until filled.

Plane stress Abaqus UMAT

Choose a channel featured in the header of iMechanica: 

Hello everyone,

I have created a UMAT code for J2 elasto-plasticity with isotropic hardening for 3D solid elements.

At this point I would like to support also plane stress shell elements. What changes in the code are

suggested? The already implemented code, takes as input the strain tensor at time tn and the strain

increment tensor and updates the stress at time tn+1 and calculates the material Jacobian and 

achieve quadratic convergence. The stress and strain tensors are manipulated as 6x1 vectors and the 

Rashid K. Abu Al-Rub's picture

Novel Metamaterials based on Triply Periodic Minimal Surfaces

Recently, there has been a growing interest in investigating the multi-functional properties of novel types of metamaterials, metastructures, and metacomposites based on triply periodic minimal surfaces (TPMS). TPMS have been discovered more than 160 years ago and thanks to additive manufacturing (3D printing) they become reality only recently and opend the doors for several applications.

Davide Bigoni's picture

Structures loaded with a force acting along a fixed straight line, or the “Reut’s column problem”

How to provide a structure with a force lying on a fixed line?
We provide the answer to this question in our paper: Bigoni and Misseroni (2019) Structures loaded with a force acting along a fixed straight line, or the “Reut’s column problem”.
Journal of the Mechanics and Physics of Solids.
Enjoy watching our video below (would you have trouble playing video on YouTube, click here to watch it).

Davide Bigoni's picture

Configurational forces and nonlinear structural dynamics

How a mass falls when attached to a flexible element with varying length?
We provide the answer to this question in our paper: Armanini, Dal Corso, Misseroni, Bigoni (2019) Configurational forces and nonlinear structural dynamics.
Journal of the Mechanics and Physics of Solids.
Enjoy watching our video below (would you have trouble playing video on YouTube, click here to watch it).

Francesco Dal Corso's picture

The Elastica Catastrophe Machine

May a catastrophe machine be realized through an elastic continuous element?
We provide a positive answer to this question in our paper: Cazzolli, Misseroni, Dal Corso. Elastica catastrophe machine: theory, design and experiments. Journal of the Mechanics and Physics of Solids.

Enjoy watching our videos below (would you have trouble playing videos on YouTube, click here to watch them).

Fan Xu's picture

Functionalized helical CNT fibre bundles as biosensors for healthcare

Mechanical mismatches between implanted electronics and biological tissues can lead to inaccurate readings and long-term tissue damage. Here, we show that functionalized multi-walled carbon nanotubes twisted into helical fibre bundles that mimic the hierarchical structure of muscle can monitor multiple disease biomarkers in vivo. The flexible fibre bundles are injectable, have a low bending stiffness and display ultralow stress under compression.

vh's picture

Prediction of forming limit diagrams using machine learning

Measuring forming limit diagrams (FLDs) is a time consuming and expensive process. Machine learning (ML) methods are a promising route to predict FLD of aluminium alloys. In the present work, we developed a machine learning (ML) based tool to establish the relationships between alloy composition / thermomechanical processing route to the material's FLD.

Emilio Martínez Pañeda's picture

Mode II fracture of an elastic-plastic sandwich layer

Dear iMechanicians,

Please find below a paper, co-authored with Ivan Cuesta and Norman Fleck, on the mode II fracture of elastic-plastic sandwich layers. The paper is part of the special issue in the Journal of Applied Mechanics dedicated to John Hutchinson's 80th anniversary and the Century Fracture Mechanics Summit.

Stephan Rudykh's picture

Soft Magneto-Active Composites

"Soft magnetoactive laminates: large deformations, transverse elastic waves and band gaps tunability by a magnetic field"  by  N. Karami Mohammadi et al (2019) has been published in November Special Issue in Journal of Applied Mechanics.

This paper is part of my group and co-author work on the topic of Soft Magneto-Active Composites:

Teng zhang's picture

Harnessing energy landscape exploration to control the buckling of cylindrical shells

Abstract: Even for relatively simple thin shell morphologies, many different buckled configurations can be stable simultaneously. Which state is observed in practice is highly sensitive to both environmental perturbations and shell imperfections. The complexity and unpredictability of postbuckling responses has therefore raised great challenges to emerging technologies exploiting buckling transitions.

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