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Multi-Axial Failure Models for Fiber-Reinforced Composites

Submitted by Ashkan Vaziri on
research
Fatigue
failure
composite materials

The increasing use of fiber-reinforced composites accentuates the need for developing multi-axial fatigue failure models for these materials. In this article (attached), we proposed several multiaxial fatigue failure models for fiber-reinforced composites considering the contribution of mean and cyclic normal stress/strain and shear stress/strain at the plane of failure and examined their capability for predicting the fatigue life of the E-glass/epoxy composite materials.

Accuracy and error estimation in extended finite element methods

Submitted by Stephane Bordas on
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Computational Mechanics Forum
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Stephane Bordas, Marc Duflot and Pierre-Olivier Bouchard announce the WCCM8 mini-symposium Link to detailed pdf description

Accuracy Assessment of the eXtended Finite Element Method: Adaptivity, Comparison with Competing Methods, Industrialisation [ID:141]

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Which phenomenological flow stress model is the best?

Submitted by Biswajit Banerjee on
research
Plasticity
flow stress models

A couple of years ago a colleague who wanted to simulate high-speed machining asked me: " Which is the best phenomenological flow stress model for metals?" I wasn't able to give an answer right away and decided to look in the literature.

What I found was, every ten years or so, a new model appears in the literature that tries to solve some of the problems of older models. However, a clear ranking of models has not been established yet.

what's most advanced open source program to multi-scale simulation?

Submitted by Roozbeh Sanaei on
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Computational Mechanics Forum
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Free Tags
multiscale mechanics
multiscale

I recently interested in multi-sclae modelling problems. and i want to know what's most advanced open source program to multi-scale simulation?

Mesoscale modeling of mechanics of carbon nanotubes: Self-assembly, self-folding and fracture

Submitted by Markus J. Buehler on
research

Using concepts of hierarchical multi-scale modeling, we report development of a mesoscopic model for single wall carbon nanotubes with parameters completely derived from full atomistic simulations. The parameters in the mesoscopic model are fit to reproduce elastic, fracture and adhesion properties of carbon nanotubes, in this article demonstrated for (5,5) carbon nanotubes. The mesoscale model enables one to model the dynamics of systems with hundreds of ultra-long carbon nanotubes over time scales approaching microseconds.

What are the appropriate values of Young's modulus and wall thickness of single-walled carbon nanotubes (SWCNTs)?

Submitted by Damodara Reddy on
research
carbon nanotubes

Hi All, Simulations and experimental results show the wide range of values for Young’s modulus (0.5 to 5.5 TPa) and wall thickness (0.066 to 0.34 nm) of carbon nanotubes (CNTs) in literature. Most of the published results say that the set of values (Young’s modulus and wall thickness of CNT) are 1 TPa  and 0.34 nm, and the product is around 0.34 TPa-nm. In my point of view this set of values may be appropriate for multi-walled carbon nanotubes. Can we use the same set of values for analysis of single-walled carbon nanotubes (SWCNTs)?  The interlayer distance between the graphene layers is 0.34 nm. Can we use this value as wall thickness of SWCNT or do we need to use atomic thickness instead of 0.34 nm?

 

Perturbation analysis of a wavy film in a multi-layered structure

Submitted by Jae-Hyun Kim on
research
vlassak_research_group
elasticity
multilayer
perturbation
undulation

A free surface in a multi-layer can experience an undulation due to surface diffusion during fabrication or etching process. In order to analyze the undulation, the elasticity solution for the undulating film is needed. Considering the undulation as a perturbation of a flat surface, a boundary value problem for 2D elasticity is formulated. The solution procedure is straightforward, but very lengthy especially for a multi-layer.

Equivalence of Virial stress to Continuum Cauchy Stress

Submitted by Arun K. Subramaniyan on
research
MD
Virial Stress

Calculating stresses in MD simulations is a controversial topic. There are two different schools of thought about the equivalence of the virial stress to the continuum Cauchy stress; for and against. Some argue based on momentum balance, that only the potential contribution to the virial stress should be considered as the continuum Cauchy stress. However, others assert that the total virial stress that contains both the kinetic and potential parts is indeed the quantity that corresponds to the Cauchy stress in continuum mechanics. We used a simple thermo-elastic analysis to verify the validity of using the total virial stress as the continuum Cauchy stress and found that the total virial stress is indeed the continuum Cauchy stress.

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