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Konstantin Volokh's blog

Konstantin Volokh's picture

Ph.D. in Mechanics of Soft Materials

Ph.D. position at the Technion – Israel Institute of Technology.  The research is concerned with experiments and modeling of failure and fracture in soft materials.  Preference will be given to candidates with background in nonlinear finite element methods and constitutive modeling. If you are interested, please send an email to me at: cvolokh@technion.ac.il with a single PDF file containing your CV, grades, names of two references, and a brief description of how your experience and background meet the requirements for this positi

Konstantin Volokh's picture

Dynamic Versus Quasi-Static Analysis of Crack Propagation in Soft Materials

Cracks usually propagate dynamically that makes them so dangerous. However, most crack simulations are based on quasi-static analyses because they are simpler than the dynamic ones. Is it correct to use quasi-static analyses instead of the dynamic ones? Will the quasi-static and dynamic simulations provide similar results? We try to answer these questions in the present work. We compare results of quasi-static and dynamic simulations of crack propagation in aneurysm material.

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Drag reduction via polymer solute: 3D numerical simulations of pipe flow

The mechanism of drag reduction via polymer additives is long debated in the literature. We present results of 3D numerical simulations of the realistic pipe flow where material instabilities develop into turbulence. We observe in the simulations that the addition of the polymer solute suppresses the chaotic turbulent motion, indeed, in accordance with the experimental observations of the phenomenon.

 

Konstantin Volokh's picture

PhD in Mechanics of Soft Materials

Ph.D. position at the Technion – Israel Institute of Technology.  The research is concerned with experiments and modeling of failure and fracture in soft materials.  Preference will be given to candidates with background in nonlinear finite element methods and constitutive modeling. If you are interested, please send an email to me at: cvolokh@technion.ac.il with a single PDF file containing your CV, grades, names of two references, and a brief description of how your experience and background meet the requirements for this positi

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CISM course "MECHANICS OF STRONGLY INHOMOGENEOUS MULTI-COMPONENT AND MULTI-LAYERED STRUCTURES"

During the period of October 3 - 7, the course "MECHANICS OF STRONGLY INHOMOGENEOUS MULTI-COMPONENT AND MULTI-LAYERED STRUCTURES" will be held at CISM, Italy. The course is offered in a hybrid format giving the possibility to attend the course also by remote (on Microsoft Teams platform).

 

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“Mechanics of soft active polymers”

EUROMECH “Mechanics of soft active polymers” Colloquium therefore welcomes the scientists, the early career researchers and industry researchers to contribute to the three sessions devoted to Theory, Experimental and numerical approaches, Applications, including sensors, actuators, robotics and energy harvesters.

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Centenary of two pioneering theories in mechanics

This note discusses the Timoshenko–Ehrenfest beam theory and the Griffith fracture theory. Both were annunciated in the West in 1921, exactly a century ago. Much progress has been made in these fields. Discussing the deficiencies of the theories might pave way ahead.

Konstantin Volokh's picture

EUROMECH “Mechanics of soft active polymers” Colloquium

EUROMECH “Mechanics of soft active polymers” Colloquium therefore welcomes the scientists, the early career researchers and industry researchers to contribute to the three sessions devoted to Theory, Experimental and numerical approaches, Applications, including sensors, actuators, robotics and energy harvesters.

Konstantin Volokh's picture

PhD in Mechanics of Soft Materials and Biological Tissues

Ph.D. position at the Technion – Israel Institute of Technology.  The research is concerned with the modeling of failure and fracture in soft materials and biological tissues.  Preference will be given to candidates with background in nonlinear finite element methods and constitutive modeling. If you are interested, please send an email to me at: cvolokh@technion.ac.il with a single PDF file containing your CV, grades, names of two references, and a brief description of how your experience and background meet th

Konstantin Volokh's picture

Failure and Fracture of Rubberlike Materials

We review some recent approaches to modeling failure and fracture of soft materials. By failure we mean the onset of damage via material instability. By fracture we mean further localization of damage into cracks with their subsequent propagation.

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Postdoc in Mechanics of Soft Materials and Biological Tissues

A new postdoctoral fellow position will be open at the Technion – Israel Institute of Technology - starting from July 2021.  The research is concerned with the modeling of failure and fracture in soft materials and biological tissues.  Potential candidates should have a Ph.D.

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Residual stresses reduce pulse wave velocity in arteries

In this note, we develop simple analytical formulas to estimate the effect of residual stresses on the pulse wave velocity in blood vessels. We combine these formulas with three constitutive models of the arterial wall: the Fung model and two models accounting for the dispersion of collagen fibers via 8 and 16 structure tensors accordingly. The residual stresses come into play with a description of the initial kinematics - the opening angle.

Konstantin Volokh's picture

Postdoc position in Mechanics of Soft Materials at the Technion

A new postdoctoral fellow position is open at the Technion – Israel Institute of Technology.  The research is concerned with the modeling of failure and fracture in soft materials.  Potential candidates should have a Ph.D.

Konstantin Volokh's picture

Mechanics of Soft Materials - second edition

This is a corrected, revised and expanded edition. I added new Chapter 11 on modeling fracture in soft materials. Arguably, fracture is the central and unsolved problem in solid mechanics. I describe a new perspective on this problem based on the material sink approach, in which momenta and mass balance are coupled.

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On incompressibility constraint and crack direction in soft solids

Most soft materials resist volumetric changes much more than shape distortions. This experimental observation led to the introduction of the incompressibility constraint in the constitutive description of soft materials. The incompressibility constraint provides analytical solutions for problems which, otherwise, could be solved numerically only. However, in the present work, we show that the enforcement of the incompressibility constraint in the analysis of failure of soft materials can lead to somewhat non- physical results. 

 

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An explanation of the drag reduction via polymer solute

The remarkable phenomenon of the drag reduction via addition of small amounts of polymer molecules to a Newtonian solvent was observed experimentally long ago. However, the theoretical explanations of this observation are not overwhelming yet. In this note, we present a possible theoretical account of the phenomenon. It is based on the use of the Navier–Stokes model with viscous strength for the solvent and the upper-convected Maxwell model for the polymer solute.

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Mechanics of Soft Materials

Springer launched new journal: Mechanics of Soft Materials

This journal offers a unique forum for research on mechanical behavior of soft materials including but not limited to polymers, elastomers, gels, rubberlike materials, soft biological materials and tissues.

The journal aims at uniting considerations of various soft materials, which exhibit similarity in many aspects of their behavior independently of the specific composition or biological function.

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Mechanics of Soft and Biological Materials

Dear Colleagues, 13th World Congress on Computational Mechanics (WCCM) will be held in New York,  July 22 - 27, 2018.

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On arterial fiber dispersion and auxetic effect

There are two polar contemporary approaches to the constitutive modeling of arterial wall with anisotropy induced by collagen fibers. The first one is based on the angular integration (AI) of the strain energy on a unit sphere for the analytically defined fiber dispersion. The second one is based on the introduction of the generalized structure tensors (GST). AI approach is very involved computationally while GST approach requires somewhat complicated procedure for the exclusion of compressed fibers. 

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Postdoctoral position at the Technion

A new postdoctoral fellow position will start on 1 November 2017 at the Technion – Israel Institute of Technology.  The position is in the area of theoretical and computational modeling of failure in soft solids.  The potential candidate should have a Ph.D.

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On cavitation in rubberlike materials

Microscopic voids can irreversibly grow into the macroscopic ones under hydrostatic tension. To explain this phenomenon it was suggested in the literature to use the asymptotic value of the hydrostatic tension in the plateau yield-like region on the stress-stretch curve obtained for the neo-Hookean model. Such an explanation has two limitations: (a) it relies on analysis of only one material model and (b) the hyperelasticity theory is used for the explanation of the failure phenomenon.

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Understanding the strength of bioinspired soft composites

Remarkable mechanical properties of biocomposites (bone, teeth, shell, antler etc.) are usually attributed to their special design where staggered mineral platelets are embedded in a protein matrix. Because of the high aspect ratio of the platelet the soft protein deforms in the shear mode predominantly providing the linkage for the hard inclusions. Mimicking Nature one might design materials with a similar architecture. 

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Fracture as a material sink

Cracks are created by massive breakage of molecular or atomic bonds. The latter, in its turn, leads to the highly localized loss of material, which is the reason why even closed cracks are visible by a naked eye. Thus, fracture can be interpreted as the local material sink. Mass conservation is violated locally in the area of material failure. We consider a theoretical formulation of the coupled mass and momenta balance equations for a description of fracture.

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