User login

You are here

research

Jamie Guest's picture

Journal Club Theme of January 2015: Topology Optimization for Materials Design

Processing technologies are rapidly advancing and manufacturers now have the ability to control material architecture, or topology, at unprecedented length scales. This opens up the design space and provides exciting opportunities for tailoring material properties through design of the material’s topology. But as seen many times in history with advancements in materials and processing technologies, the natural default is to rely on familiar shapes and structure topologies.

Bisheswor's picture

Multiscale modelling of load transfer in grephene laminates

Hi everyone,

                     First  little bit of background over my model.

My model is 3d,deformable solid extrude and consist of grephe flakes  each flakes depth is 0.33 nm and length we can input,We can input the total   box size in nm ...no of layers in that box...and the size of flakes...and the layers are generated automatically with no pattern.And Both side are supported with support.And one side is fixed and another is provided with displacement load.The element is 4 node linear terahedron.

target

Moving Load in ABAQUS

I am trying to incorporate moving point load on a beam in ABAQUS but not sure which is the best way to do it? Can someone help?

mohsenzaeem's picture

Effect of variant strain accommodation on the three-dimensional microstructure formation during martensitic transformation: Application to zirconia

This paper computationally investigates the effect of martensitic variant strain accommodation on the formation of microstructural and topological patterning in zirconia. We used the phase-field technique to capture the temporal and spatial evolution of embryonic formation of the monoclinic phase in tetragonal single crystals. The three-dimensional simulations were able to capture the formation of all the possible monoclinic variants. We used the multivariant single embryo as an initial condition to mitigate the lack of nucleation criteria at the mesoscale.

Cai Shengqiang's picture

Diffusion-induced wrinkling instability in a circular poroelastic plate

A poroelastic material can imbibe solvent and swell. When the material swells inhomogeneously or

swells under external constraints, stresses can develop inside the material. The stresses can trigger

mechanical instabilities in the material or even break the material, which have been often observed

in experiments. In this paper, we study the wrinkling instability of a circular poroelastic plate, in

the process of solvent molecules migrating into the plate from the edge. The critical conditions for

Cai Shengqiang's picture

wet adhesion between two soft layers

Two solids can adhere to each other in the presence of a liquid bridge between them, which is called wet adhesion. When the solid is soft, the liquid bridge can cause deformation in the material, and in turn, the deformation may have dramatic effects on the wet adhesion. To investigate the effect, in this article, we calculate the deformation in two soft layers with different separations and connected by a liquid bridge. We illustrate the effect of deformation in the soft layers on the adhesive force.

Cai Shengqiang's picture

Drying-induced cavitation in a constrained hydrogel

Cavitation can be often observed in soft materials. Most previous studies were focused on cavitation in an elastomer, which is under different mechanical loadings. In this paper, we investigate cavitation in a constrained hydrogel induced by drying. With taking account of surface tension and chemo-mechanics of gels, we calculate the free energy of the system as a function of cavity size. The free energy landscape shows double-well structure, analogous to first-order phase transition.  Above the critical humidity, a cavity inside the gel is tiny.

Sulin Zhang's picture

Ripplocations = surface ripples + dislocations ?

Dislocations are topological line defects in three-dimensional crystals. Same-sign dislocations repel according to Frank s rule . This rule is broken for dislocations in van der Waals (vdW) layers, which possess crystallographic Burgers vector as ordinary dislocations but feature surface ripples”  due to the ease of bending and weak vdW adhesion of the atomic layers.

S Patel's picture

Abaqus data extracting

Choose a channel featured in the header of iMechanica: 

hello sir/madam

 

i am performing the analysis on biamaterial crack problem on CT specimen for detrmining the plastic zone and i found mises data as i assigning the two sections for these analysis. Now i have found nonsequence order of the mises value due to clashing of mises value at common nodes. so, any one suggest me how to get mises values at each node either in proper order or with geomatrical coordinates. 

Cavitation in Rubber: An Elastic Instability or a Fracture Phenomenon?

The viewpoint that cavitation in rubber — that is, the sudden growth of inherent defects in rubber into large enclosed cavities in response to external stimuli — is a purely elastic phenomenon has long been known to be fundamentally incomplete. Essentially, this is because the local stretches around the defects at which cavitation initiates far exceed the elastic limit of the rubber, which therefore ought to inelastically deform by fracturing to accommodate their growth.

marco.paggi's picture

MUSAM - Multi-scale Analysis of Materials - Annual report 2014

Dear Colleague,

 

I would like to inform you that the annual report on the scientific and educational activities carried out by the research unit MUSAM on Multi-scale Analysis of Materials at IMT Lucca during 2014 can be downloaded from the following link:

 

Contact between two surfaces in Abaqus

Choose a channel featured in the header of iMechanica: 

Hi,

Recoverable plasticity in penta-twinned metallic nanowires governed by dislocation nucleation and retraction

AbstractThere has been relatively little study on time-dependent mechanical properties of nanowires, in spite of their importance for the design, fabrication and operation of nanoscale devices.

Case Study: Modelling Ultrasonic Array Response of Real Cracks

Stress corrosion cracks can be a serious problem in many engineering industries, and especially so for critical parts. While an ultrasonic transducer can be used for the non-destructive evaluation of cracks with simple shapes, complex branching cracks, such as stress corrosion cracks, require ultrasonic arrays that consist of multiple transducers and are able to inspect at multiple angles.

mohsenzaeem's picture

Quantitative modeling of the equilibration of two-phase solid-liquid Fe by atomistic simulations on diffusive time scales

Molecular dynamics (MD) simulations based on the modified-embedded atom method (MEAM) and a phase-field crystal (PFC) model are utilized to quantitatively investigate the solid-liquid properties of Fe. A set of second nearest-neighbor MEAM parameters for high-temperature applications are developed for Fe, and the solid-liquid coexisting approach is utilized in MD simulations to accurately calculate the melting point, expansion in melting, latent heat, and solid-liquid interface free energy, and surface anisotropy.

Add XFEM crack to an already deformed model

I hope this can be done and I want to say thank you in advance for any feedback.

I have already completed a simulation of a plate with a hole and pulling a mandrel through the hole to expand it and create a plastically deformed hole.

Now, I would like to take this plastically deformed hole, add an XFEM crack and vertically pull to simulate a tension test.

Can this be done? 

Min Yi's picture

A constraint-free phase field model for ferromagnetic domain evolution

A continuum constraint-free phase field model is proposed to simulate the magnetic domain evolution in ferromagnetic materials. The model takes the polar and azimuthal angles (ϑ1, ϑ2), instead of the magnetization unit vector m(m1,m2,m3), as the order parameters. In this way, the constraint on the magnetization magnitude can be exactly satisfied automatically, and no special numerical treatment on the phase field evolution is needed. The phase field model is developed from a thermodynamic framework which involves a configurational force system for ϑ1 and ϑ2.

Amit Acharya's picture

The metric-restricted inverse design problem

Amit Acharya         Marta Lewicka         Mohammad Reza Pakzad

We study a class of design problems in solid mechanics, leading to a variation on the
classical question of equi-dimensional embeddability of Riemannian manifolds. In this general new
context, we derive a necessary and sufficient existence condition, given through a system of total
differential equations, and discuss its integrability. In the classical context, the same approach
yields conditions of immersibility of a given metric in terms of the Riemann curvature tensor.
In the present situation, the equations do not close in a straightforward manner, and successive
differentiation of the compatibility conditions leads to a more sophisticated algebraic description
of integrability. We also recast the problem in a variational setting and analyze the infimum value
of the appropriate incompatibility energy, resembling "non-Euclidean elasticity".

NSF - Mechanics of Materials and Structures

Dear colleagues,

There have been two changes at NSF that do affect the imechanica community. I would like to bring these to your attention.

The rheology of non-dilute dispersions of highly deformable viscoelastic particles in Newtonian fluids

Abstract: We present a model for the rheological behaviour of non-dilute suspensions of initially spherical viscoelastic particles in viscous fluids under uniform Stokes flow conditions. The particles are assumed to be neutrally buoyant Kelvin–Voigt solids undergoing time-dependent finite deformations and exhibiting generalized neo-Hookean behaviour in their purely elastic limit. We investigate the effects of the shape dynamics and constitutive properties of the viscoelastic particles on the macroscopic rheological behaviour of the suspensions.

Jaafar El-Awady's picture

Unravelling the physics of size-dependent dislocation-mediated plasticity

Size-affected dislocation-mediated plasticity is important in a wide range of materials and technologies. The question of how to explain and predict the effect of size on the properties and response of materials has been at the forefront of mechanics and materials research.

mohsenzaeem's picture

Two-phase solid–liquid coexistence of Ni, Cu, and Al by molecular dynamics simulations using the modified embedded-atom method

The two-phase solid–liquid coexisting structures of Ni, Cu, and Al are studied by molecular dynamics (MD) simulations using the second nearest-neighbor (2NN) modified-embedded atom method (MEAM) potential. For this purpose, the existing 2NN-MEAM parameters for Ni and Cu were modified to make them suitable for the MD simulations of the problems related to the two-phase solid–liquid coexistence of these elements.

mohsenzaeem's picture

A Review of Quantitative Phase-Field Crystal Modeling of Solid–Liquid Structures

Phase-field crystal (PFC) is a model with atomistic-scale details acting on diffusive time scales. PFC uses the density field as its order parameter, which takes a constant value in the liquid phase and a periodic function in the solid phase. PFC naturally takes into account elasticity, solid–liquid interface free energy, surface anisotropy, and grain boundary free energy by using this single-order parameter in modeling of coexisting solid–liquid structures.

Pages

Subscribe to RSS - research

Recent comments

More comments

Syndicate

Subscribe to Syndicate