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Nanoindentation processes in full view

The microelectronics revolution is one of the most influential drivers of current industrial developments. To probe the mechanical properties of ever shrinking materials and components, nanoindentation has come to be an omnipresent and indispensable method. In a recent combined experimental and computational approach, an international team of scientists was for the first time able to resolve the dynamic atomistic processes taking place at the elastic-plastic transition during nanoindentation.

Legato team fights COVID-19 in Luxembourg

Dear all,

An update on the http://www.legato-team.eu at work in the COVID19 response in Luxembourg. 

Check out http://www.ariana-tech.com a joint venture between Kyoto and Luxembourg. 

Ramathasan Thevamaran's picture

Environmentally induced exceptional points in elastodynamics

We study the nature of an environment-induced exceptional point in a non-Hermitian pair of coupled mechanical oscillators. The mechanical oscillators are a pair of pillars carved out of a single isotropic elastodynamic medium made of aluminum and consist of carefully controlled differential losses. The interoscillator coupling originates exclusively from background modes associated with the “environment,” that portion of the structure which, if perfectly rigid, would support the oscillators without coupling.

Ramathasan Thevamaran's picture

Independent control of dynamic material properties by exploiting structural hierarchy and intrinsic structural gradients

Achieving high damping and stiffness is challenging in common materials because of their inter-dependent scaling. Controlling extreme mechanical waves requires synergistically enhanced damping and stiffness. We demonstrate superior damping and stiffness in vertically aligned carbon nanotube (VACNT) foams that are also independently controllable by exploiting their synthesis-tailored structural hierarchy and structural gradients. They exhibit frequency- and amplitude-dependent responses with dramatically tunable dynamic stiffness while maintaining constant damping.

Ramathasan Thevamaran's picture

Superior Energy Dissipation by Ultrathin Semicrystalline Polymer Films Under Supersonic Microprojectile Impacts

Distinct deformation mechanisms that emerge in nanoscale enable the nanostructured materials to exhibit outstanding specific mechanical properties. Here, we present superior microstructure- and strain-rate-dependent specific penetration energy (up to ∼3.8 MJ/kg) in semicrystalline poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) thin films subjected to high-velocity (100 m/s to 1 km/s) microprojectile (diameter: 9.2 μm) impacts.

Teng Li's picture

EML Webinar by Prof. Katia Bertoldi on May 13, 2020

 

EML Webinar on May 13, 2020 will be given by Prof. Katia Bertoldi at Harvard University via Zoom meeting. 

Ajeet Kumar's picture

A singularity free approach for Kirchhoff rods having uniformly distributed electrostatic charge

We present a singularity free formulation and its efficient numerical implementation for the spatial deformation of Kirchhoff rods having uniformly distributed electrostatic charge. Due to the presence of continuously distributed charge, the governing equations of the Kirchhoff rod become a system of integro-differential equations which is singular at every arc-length. We show that this singularity is of removable type which, ones removed, makes the system well defined everywhere. No cutoff length or mollifier is used to remove this singularity.

emuna's picture

Circumferential instabilities in radially incompatible tubes

The full paper can be found at:

https://authors.elsevier.com/c/1b2plc7qwXwm0

Abstract:

Geometric incompatibilities are ubiquitous in natural structures and are recently being exploited in synthetic

structures to enhance the performance of soft systems. In this work we focus on infinitely long bi-layer

Teng Li's picture

EML Webinar by Prof. Xuanhe Zhao on May 6, 2020

EML Webinar on May 6, 2020 will be given by Prof. Xuanhe Zhao at MIT via Zoom meeting. 

Title: Extreme Mechanics of Soft Materials for Merging Human-Machine Intelligence

Antonio Papangelo's picture

Self-excited vibrations due to viscoelastic interactions

Self-excited vibrations represent a big concern in engineering, particularly in automotive, railway and aeronautic industry. Many lumped models have been proposed over the years to analyze the stability of such systems. Among the instability mechanisms a falling characteristic of the friction law and mode coupling have been shown to give friction-excited oscillations. The mass-on-moving-belt system has been studied extensively in Literature, very often adopting a prescribed form of the friction law and linearizing the contact stiffness.

Parag Tandaiya's picture

Mechanistic origins of work hardening in shape memory alloy particle reinforced ex-situ bulk metallic glass matrix composites

Monolithic Bulk Metallic Glasses (BMGs) exhibit strain softening or elastic-perfectly plastic response under uniaxial loading. However, shape memory alloy particle reinforced BMG matrix composites show strong work hardening in experiments. In our recent paper published in Scripta Materialia, we explain the Mechanistic origins of work hardening in shape memory alloy particle reinforced ex-situ bulk metallic glass matrix composites through three dimensional finite element simulations.

santiago.orrego's picture

Bioinspired Materials with Self‐Adaptable Mechanical Properties

Dear iMechanica,

We are very excited to share the news that our recent work on bioinspired materials with self‐adaptable mechanical properties is published in Advanced Materials.

https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.201906970

The work was done in collaboration with Prof. Kang from Johns Hopkins University

mokarram76's picture

Ecoflex polymer : Comprehensive experimental study and constitutive modelling

We have published two papers on Ecoflex, a popular silicone polymer in recent days. The polymer is largely temperature- and strain rate-insensitive. It comes up with several Shore Hardnesses. We characterize five Shores and develop a novel Shore-dependent modelling framework

Mechanics of Materials >> https://www.sciencedirect.com/science/article/pii/S016766362030020X

vacary's picture

First Overlay Journal in Solid Mechanics is launched. Call for handling editors

Dear members of iMechanica,

We are very pleased to announce the born of the first overlay journal in Solid Mechanics the so-called

 Journal of Theoretical, Computational and Applied Mechanics https://jtcam.episciences.org

which is a scholarly journal, provided on a Fair Open Access basis, without cost to both readers and authors. The Journal aims to select publications of the highest scientific caliber in the form of either original research or review in Solid Mechanics. 

Machine Learning for Fracture Mechanics

Safer batteries, more efficient gas-turbine engines and solar cells, all require better-engineered nanocomposite materials. There is a limitation though -- how to investigate the fracture mechanics of these materials? Machine learning can help us overcome this limitation.

Mohammadreza_Aali's picture

Investigation of Spindle Rotation Rate Effects on the Mechanical Behavior of Friction Stir Welded Ti 4Al 2V Alloy

Nowadays, titanium and its alloys are widely utilized in various industrial parts in such areas as the petrochemical, medical, and automotive industries; However, due to structural considerations, the application is problematic in cases of joining. Ti 4Al 2V is a new type of titanium alloy, that in point of the structure is near to the α-series, which have many applications in critical conditions (moisture, steam, temperature, etc.).

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