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Chiqun Zhang's picture

Computational modeling of tactoid dynamics in chromonic liquid crystals

Chiqun Zhang            Amit Acharya            Noel J. Walkington            Oleg D. Lavrentovich

Motivated by recent experiments, the isotropic-nematic phase transition in chromonic liquid crystals is studied. As temperature decreases, nematic nuclei nucleate, grow, and coalesce, giving rise to tactoid microstructures in an isotropic liquid. These tactoids produce topological defects at domain junctions (disclinations in the bulk or point defects on the surface). We simulate such tactoid equilibria and their coarsening dynamics with a model using degree of order, a variable length director, and an interfacial normal as state descriptors. We adopt Ericksen's work and introduce an augmented Oseen-Frank energy, with non-convexity in both interfacial energy and the dependence of the energy on the degree of order. A gradient flow dynamics of this energy does not succeed in reproducing some simple expected feature of tactoid dynamics. Therefore, a strategy is devised based on continuum kinematics and thermodynamics to represent such features. The model is used to predict tactoid nucleation, expansion, and coalescence during the process of phase transition. We reproduce observed behaviors in experiments and perform an experimentally testable parametric study of the effect of bulk elastic and tactoid interfacial energy parameters on the interaction of interfacial and bulk fields in the tactoids.

Meisam. Asgari's picture

Theoretical and experimental constitutive modelling of soft materials at the nano scale: Cylindrical micellar filaments

We present theoretical and experimental descriptions of the elasticity of cylindrical micellar filaments using micro-mechanical and continuum theories, and Atomic Force Microscopy. Following our micro-mechanical elasticity model for micellar filaments [Asgari, Eur. Phys. J. E 2015, 38(9)], the elastic bending energy of hemispherical end caps is found. The continuum description of the elastic bending energy of a cylindrical micellar filament is also derived using constrained Cosserat rod theory.

Ruobing Bai's picture

Localized Deformation in Plastic Liquids on Elastomers

Dear Colleagues,

Attached please find our recent paper “Localized Deformation in Plastic Liquids on Elastomers”.

Title: Localized Deformation in Plastic Liquids on Elastomers

Authors: Xavier P. Morelle, Ruobing Bai and Zhigang Suo


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Hello Everyone,


Does any one have the source code of this book.




I need it to understand the plasticity implementation in FEA.


Please mail me at




ahmedettaf's picture

A new hybrid numerical scheme for modeling elastodynamics in unbounded media with near-source heterogeneities

The Finite Difference (FD) and the Spectral Boundary Integral (SBI) methods have been used extensively to model spontaneously propagating shear cracks in a variety of engineering and geophysical applications. In this paper, we propose a new modeling approach, in which these two methods are combined through consistent exchange of boundary tractions and displacements. Benefiting from the flexibility of FD and the efficiency of spectral boundary integral methods, the proposed hybrid scheme will solve a wide range of problems in a computationally efficient way.

Flavio Stochino's picture

Eigenerosion for static and dynamic brittle fracture

In contrast to many numerical methods, the eigenerosion approach yields a convenient description of fracture handled in the postprocessing part of a Finite Element Analysis (FEA). Its fully energetic formulation avoids the introduction of extra degrees of freedom to model fracture propagation. Following previous works on eigenerosion, in this publication, a modified formulation of eigenfracture it is introduced, where it is distinguished between compression and tension loaded state.

Alejandro Ortiz-Bernardin's picture

Veamy: an extensible object-oriented C++ library for the virtual element method

This paper summarizes the development of an object-oriented C++ library for the virtual element method (VEM) named Veamy, whose modular design is focused on its extensibility. The two-dimensional linear elastostatic problem has been chosen as the starting stage for the development of this library. In contrast to the standard finite element method, the VEM in two dimensions uses polygonal finite element meshes.

msaeidi's picture

High thermal conductivity through simultaneously aligned polyethylene lamellae and graphene nanoplatelets

The effect of simultaneous alignment of polyethylene (PE) lamellae and graphene nanoplatelets (GnP) on thermal conductivity (k) of PE-GnP composites is investigated. Measurements reveal a large increase of 1100% in k of the aligned PE-GnP composite using 10 weight% GnPs relative to unoriented pure PE. Rate of increase of k with applied strain for the pure PE-GnP composite with 10 wt% GnP is found to be almost a factor of two higher than the pure PE sample, pointing to the beneficial effect of GnP alignment on k enhancement.

Wenbin Yu's picture

Time to Register for 2017 American Society for Composites Annual Conference at Purdue

Dear Colleagues, if you are interested in the state-of-the-art R&D in composite materials, you might want to attend the American Society for Composites Anuual Meeting at Purdue (10/22-25, 2017). The registeration is open at

marco.paggi's picture

Identification of higher-order continua equivalent to a Cauchy elastic composite

Dear Mechanician,

A novel method for the identification of higher-order continua equivalent to a Cauchy composite has been published, as a result of the collaboration between the following two ERC projects:

Full paper:

Jingjie Yeo's picture

Unusually low and density-insensitive thermal conductivity of three-dimensional gyroid graphene Graphene has excellent mechanical, thermal and electrical properties. However, there are limitations in utilizing monolayers of graphene for mechanical engineering applications due to its atomic thickness and lack of bending rigidity. Synthesizing graphene aerogels or foams is one approach to utilize graphene in three-dimensional bulk forms. Recently, graphene with a gyroidal geometry has been proposed.

Antonio Papangelo's picture

Load-separation curves for the contact of self-affine rough surfaces

Load separation curves between self-affine rough surfaces have been studied by means of extensive numerical simulations. The results of the comparison with the two main contact mechanics theories have been reported.

Rong Long's picture

Fracture Mechanics of Soft Materials

Rong Long

Department of Mechanical Engineering, University of Colorado Boulder

Influence of surface tension in the surfactant-driven fracture of particulate monolayers

Dear Colleagues,

  I thought some of you may be interested in our recent paper which has been accepted to Soft Matter.  The article is available online, here:

   It contains a new model for the fracture of particulate rafts, and some new experimental results as well.  Questions are welcome. 

mohsenzaeem's picture

Generalized stacking fault energies, ductilities, and twinnabilities of CoCrFeNi-based face-centered cubic high entropy alloys

Effects of Cu, Mn, Al, Ti, Mo on generalized stacking fault energies, Rice-criterion ductilities, and twinabilities of CoCrFeNi-based face-centered cubic high entropy alloys were investigated using density functional theory calculations. The calculated barrier energies and twinnabilities revealed that the addition of Ti or Mo increased the tendency of dislocation glide and deformation twinning, while addition of Mn, Cu and relatively high amount of Al facilitated dislocation gliding and martensitic transformation. Low amount of Al resulted in only dislocation gliding.

Mike Ciavarella's picture

Some Closed-Form Results for Adhesive Rough Contacts Near Complete Contact on Loading and Unloading in the Johnson, Kendall, and Roberts Regime

Michele Ciavarella  Yang Xu Robert L. Jackson

Some Closed-Form Results for Adhesive Rough Contacts Near Complete Contact on Loading and Unloading in the Johnson, Kendall, and Roberts Regime

Journal of Tribology Copyright VC 2018 by ASME JANUARY 2018, Vol. 140 / 011402-1


Recently, generalizing the solution of the adhesiveless random rough contact proposed

by Xu, Jackson, and Marghitu (XJM model), the first author has obtained a model for

adhesive contact near full contact, under the Johnson, Kendall, and Roberts (JKR)

Dependence of Equilibrium Griffith Surface Energy on Crack Speed in Phase-Field Models for Fracture Coupled to Elastodynamics

Phase-field models for crack propagation enable the simulation of complex crack patterns without complex and expensive tracking and remeshing as cracks grow. In the setting without inertia, the crack evolution is obtained from a variational energetic starting point, and leads to an equation for the order parameter coupled to elastostatics. Careful mathematical analysis has shown that this is consistent with the Griffith model for fracture. Recent efforts to include inertia in this formulation have replaced elastostatics by elastodynamics.

Ruobing Bai's picture

Fatigue fracture of tough hydrogels

Dear colleagues,

Attached please find our new paper "Fatigue fracture of tough hydrogels" published on Extreme Mechanics Letters.


Fatigue fracture of tough hydrogels

Ruobing Bai, Quansan Yang, Jingda Tang, Xavier P. Morelle, Joost Vlassak, Zhigang Suo

ntuecd's picture

Model two heat source for arc welding simulation using ls-dyna??

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i am trying to compute the temperature distribution in arc welding simulation by using two heat source simultaneously (first one on the top of the plate and second one on the bottom of the plate). For this simulation i am using the software LS-DYNA. But, unfortunately my simulation terminate with following error which i am unable to understand:


*** Error 60110 (IMP+110)
terminating : MF2 Factorization error 14
E r r o r t e r m i n a t i o n


ntuecd's picture

Temperature field simulation by using LS-DYNA??

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Hallo welding simulation experts,


i am trying to simulate the temperature field in a single pass weld by using the commercial software LS-DYNA. I had simulated the welding torch by using beam element concept and it works perfect.


Zhaohe Dai's picture

Measuring Interlayer Shear Stress in Bilayer Graphene

Monolayer two-dimensional (2D) crystals exhibit a host of intriguing properties, but the most exciting applications may come from stacking them into multilayer structures. Interlayer and interfacial shear interactions could play a crucial role in the performance and reliability of these applications, but little is known about the key parameters controlling shear deformation across the layers and interfaces between 2D materials. Herein, we report the first measurement of the interlayer shear stress of bilayer graphene based on pressurized microscale bubble loading devices.


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