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Giorgio Carta's picture

Transmission and localisation in ordered and randomly-perturbed structured flexural systems

The paper presents a novel analysis of localisation and transmission properties of randomly-perturbed flexural systems. Attention is given to the study of propagation regimes and the connection with localised resonance modes in the context of Anderson's localisation. The analytical study is complemented with numerical simulations relevant to the design of efficient vibration isolation systems.

 

Eigenvalues, reflected and transmitted energy, localisation factors for the examined bi-coupled random system:

Mario Juha's picture

LES and RANS simulation of wind- and wave-forced oceanic turbulent boundary layers in shallow water with wall modeling

Large-eddy simulation (LES) and Reynolds-averaged Navier-Stokes (RANS) simulation of wind and wave forced oceanic turbulence in unstratified shallow water are performed in order to investigate the influence of wall modeling on results. The LES is also used to investigate the dependence of results on downwind and crosswind lengths of the computational domain, representative of a shallow shelf coastal ocean (10-to-30 m deep) unaffected by lateral boundaries.

Electroelasticity of polymer networks

This work introduces a new microscopically-motivated model for the electromechanical response of elastomers:

http://ac.els-cdn.com/S0022509615303525/1-s2.0-S0022509615303525-main.pdf?_tid=1db1e302-202a-11e6-8a60-00000aacb361&acdnat=1463927774_d9ad1fa74b5b42fafcb28a8b6b2c9b60

The merit of this novel model is demonstrated in the following paper

Mirkhalaf's picture

Polymer constitutive modelling: Formulation and computational aspects

  • This work formulates an elasto-viscoplastic model at finite strains.
  • A particularly efficient numerical integration algorithm is presented.
  • A closed-form analytical expression is derived for the consistent tangent operator.
  • The non-linear behaviour of polymers is captured in the numerical examples.
  • Quadratic rate of convergence is successfully achieved.
Douglas P Holmes's picture

Geometry and mechanics of thin growing bilayers

Matteo Pezzulla, Gabriel P. Smith, Paola Nardinocchi, and Douglas P. Holmes, Soft Matter, 12, 4435-4442, (2016).

 

paulwatton's picture

Funded PhD studentship: Modelling of Fibroblast Mechanobiology

Supervisor: PN Watton, Department of Computer Science, University of Sheffield.

Co-supervisors: Prof Ray Ogden, School of Mathematics and Statistics & Dr Huabing Yin, Bioengineering, University of Glasgow

We are seeking applications from motivated mathematics, science or engineering graduates with strong mathematical/computational modelling skills interested in studying for a Ph.D. in an exciting interdisciplinary environment.

Harnessing atomistic simulations to predict the rate at which dislocations overcome obstacles

Predicting the rate at which dislocations overcome obstacles is key to understanding the microscopic features that govern the plastic flow of modern alloys. In this spirit, the current manuscript examines the rate at which an edge dislocation overcomes an obstacle in aluminum. Predictions were made using different popular variants of Harmonic Transition State Theory (HTST) and compared to those of direct Molecular Dynamics (MD) simulations. The HTST predictions were found to be grossly inaccurate due to the large entropy barrier associated with the dislocation–obstacle interaction.

Giorgio Carta's picture

Continuous and discrete microstructured materials with null Poisson's ratio

In this paper we propose different classes of isotropic microstructured media with tunable Poisson's ratio. The elastic periodic systems are continuous porous media and two- and three-dimensional lattices. The microstructural parameters can be tuned in order to have an effective Poisson's ratio equal to zero. The connection between microstructural parameters and effective properties is shown in detail both analytically and numerically.

 

Continuous system with null Poisson's ratio:

Giorgio Carta's picture

Design of a porous material with isotropic negative Poisson's ratio

This paper proposes the design of a two-dimensional porous solid with omnidirectional negative Poisson's ratio. The hexagonal periodic distribution of the pores makes the effective behavior isotropic. Both experimental tests and numerical simulations have been performed to determine the effective properties of the porous solid. A parametric study on the effect of the geometrical microstructural parameters is also presented. This auxetic structure is easy to fabricate and can be very useful in several engineering applications.

 

ahmed.hussein's picture

Quantifying dislocation microstructure evolution and cyclic hardening in fatigued face-centered cubic single crystals

Discrete dislocation dynamics simulations were performed to investigate the dislocation microstructure evolution and cyclic hardening during the early stages of fatigue loading in nickel single crystals. The effects of the crystal size and initial dislocation densities on both the mechanical response and the evolution of dislocation microstructure were quantified.

Line Spring elements errors

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Hello, All

***Problem ***

Failure pressure for Steam generator tube having 2 axial cracks. I am following one paper in that paper they found failure pressure by finding J and K values for line spring elements for different pressure. The pressure at which it approach material JIC(92N/mm) and KIC(65Mpa*sqrt(m)) value is considered as failure pressure or coalescence pressus

**Modelling** 

Generate master curve for viscoelasticity

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Hello,

I would like to generate a master curve (e.g. of the storage modulus) based on frequency-sweeps experiment for different temperatures.

Basically, I need to determine the shifts in order to construct the master curve. I want to automatize the process with Matlab, instead of shifting the data by hand. And I don't want to use WLF or Arrhenius methods.

I want to determine the shifts for each temperature s.t. I get a smooth master curve (minimize the error using least square).

renganathan sekar's picture

How do I rectify an error regarding memory storage when I generate substructures in ABAQUS?

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I have been trying to generate a substructure in ABAQUS for a big diameter roller bearing. I have used two reference points, one each for inner and outer raceways to couple the inner and outer raceway surfaces. I have two steps in the analysis. The first step is Frequency followed by Substructure generation step. The analysis runs fine till the end of first step and calculates the eigen frequencies. When the second step starts, following error message appears.

" Element 439473 requires more than 2GB of memory for storage"

How to analysis Fatigue of shaft using Ansys or Ncode designlife?

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I use ANSYS APDL with code for my shaft with two coating layers(interlayer and coating layer). I already analysis stress of shaft with Ansys. the result is ok and i exported to .RST file. But , when i input my shaft to Ncode, I can't find the interlayer and coating layers.I think this shaft have 3 part(subtrate, interlayer, coating layer)
!substrate materials

Young's modulus (Mpa): 2.1e5
Poisson's ratios:0.3
Density(ton/mm3):8.03e-9

! interlayer material

Yield behaviour of trabecular bone

A recently published paper  "Evaluating the macroscopic yield behaviour of trabecular bone using a nonlinear homogenisation approach" links the micromechanics of bone to its macroscopic behaviour. The paper may be of interest to colleagues on this forum. The abstract is provided below.

Abstract:

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