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Mechanical Threshold Stress model for 6061-T6 aluminum alloy

I have attached a copy of my McMat07 talk below.  The talk is about a modified mechanical threshold stress (Follansbee-Kocks) model that can be used for strain rates > 1000 /s and high homologous temperatures.  In the model, the pressure dependence of the flow stress arises from the pressure dependence of the shear modulus.  Even after using the most accurate models for the shear modulus (and the melting temperature) we find that the pressure sensitivity of the flow stress is underestimated by our model (by quite a bit).

How to assign tensile and compressive stress-strain curve in Ansys.

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Hi everyone

Peridynamic theory vs. classical continuum theory

Dr. Stewart Silling has provided me with a copy of his talk on Peridynamic theory that he presented at McMat 2007.  The PDF file of the talk is attached below.

In order to deal with classical material models and volume constraints, Dr. Silling has modified the original theory to allow for forces that are not necessarily pairwise. A bit on that is included in the talk.

BoJing Zhu's picture

Future of fracture mechanics

If possible,share your opinion (idea) about the future trend of fracture mechanics. Thanks!

Wugui Jiang's picture

help for applying the cohesive model to predict the fatigue lift for bimaterial system with perfect interfaces

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Dear fellows,

We will predict the fatigue life for the metal-ceramic multilyer devices subjected to cyclic load in service . Residual stresses are induced during  high- temperature process in the devices, which were known in the previous work. Considering the bimaterial interface as a weak plane, no  geometric discontinuity are taken into account, i.e., perfect interfaces are considered.

 How to construct the cohesive interface model (no initial crack)?

appreciate your advice in advance.



Frank Zoellner's picture

velocity correction SPH

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Hello Everybody,

Monaghan suggested for the SPH velocity correction an epsilon value of 0.5. If i use that in my code, my fluid behaves like pudding, not like water. It behaves like water when i use 0.001 or something similar. My start conditions are: rho = 1000, smoothing length h = particle spacing dx, sampling neighbours within a radius of 2h. Has anybody an idea? 



Crack propagation with automatic remeshing in ABAQUS?

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My aim is
to carry out calculation of 2D crack propagation with ABAQUS 6.6.

Section 11.4.3
“CRACK PROPAGATION ANALYSIS” is providing an overview of what the software can
do, and I must say I am disappointed, for two main reasons:


Erkan Oterkus's picture

Stress analysis of composite cylindrical shells with an elliptical cutout

Stress analysis of composite cylindrical shells with an elliptical cutout  
Erkan Oterkus & Erdogan Madenci & Michael P. Nemeth


Arash_Yavari's picture

Anharmonic lattice statics analysis of 180^o and 90^o ferroelectric domain walls in PbTiO3

This paper presents an anharmonic lattice statics analysis of 180 and 90 domain walls in tetragonal ferroelectric perovskites. We present all the calculations and numerical examples for the technologically important ferroelectric material PbTiO3. We use shell potentials that are fitted to quantum mechanics calculations. Our formulation places no restrictions on the range of the interactions. This formulation of lattice statics is inhomogeneous and accounts for the variation of the force constants near defects.

ErwanVerron's picture

Study of the simple extension tear test sample for rubber with Configurational Mechanics

The simple extension tear test-piece also referred to as the trousers sample is widely used to study crack propagation in rubber. The corresponding energy release rate, called tearing energy for rubber materials, was first established by Rivlin and Thomas (Rupture of rubber. I. Characteristic energy for tearing. J. Polym. Sci., 10:291–318, 1953); a second derivation was proposed later by Eshelby (The calculation of energy release rates. In G. C. Sih, H. C. van Elst, and D. Broek, editors, Prospects of Fracture Mechanics, 69–84, Leyden, Noordhoff, 1975).

Tao Liu's picture

Bi-functional optimization of actively cooled, pressurized hollow sandwich cylinders with prismatic cores

All metallic, hollow sandwich cylinders having ultralight two-dimensional prismatic cores are optimally designed for maximum thermo-mechanical performance at minimum mass. The heated cylinder is subjected to uniform internal pressure and actively cooled by forced air convection. The use of two different core topologies is exploited: square- and triangular-celled cores. The minimum mass design model is so defined that three failure modes are prevented: facesheet yielding, core member yielding, and core member buckling.

aitang's picture

I'd like to know something about Carbon Fiber

Dear all,

 Recently I got something info from my colleagues about Carbon Fiber. Now more and more this kind material is using in Aerospace, and it has a very nice future.

As it's very abrasive when cutting it, so there's lots of problems for machining.

So, could you anyone give me some info about this material? or where can I go for it?

 thanks a lot

Nanomechanics and Nanostructured Multifunctional Materials: Experiments, Theories, and Simulations

Dr. Jun Lou and Dr. Junlan Wang are co-editing a special issue on Nanomechanics and Nanostructured Multifunctional Materials: Experiments, Theories, and Simulations for Journal of Nanomaterials, an open access journal. Papers on latest developments on all aspects of nanomechanics and nanostructured materials are welcome. Deadline for manuscript submission is September 01, 2007.
For more details, please check JNM website

Cell mechanics workshop at University of Illinois with NSF fellowships

Apply for NSF fellowships to attend 1-week long workshop on cell mechanics, July 31-Aug 3, 2007.

Check out  

Jie Wang's picture

Influence of depolarization field on polarization states in epitaxial ferroelectric thin films with biaxial misfit strains

Depolarization field and misfit strain are two important factors that may greatly influence the properties of ferroelectric thin films. The effect of depolarization field on polarization states of single-domain ferroelectric thin films with nonequally biaxial in-plane misfit strains are studied in the present work by numerically solving three coupled Euler-Lagrange equations, which are derived from the minimization of total free energy.

Biomolecular detection by a cantilever functionalized by RNA aptamers as receptor molecules

We have recently reported the label-free detection of HCV (Hepatitis C Virus) helicase by using a resonating microcantilever whose surface is functionalized by RNA aptamers as receptor molecules. This work was accepted for publication at Biosensors & Bioelectronics.


Kaushik Dayal's picture

Kinetics of phase transformations in the peridynamic formulation of continuum mechanics


We study the kinetics of phase transformations in solids using the peridynamic formulation of continuum mechanics. The peridynamic theory is a nonlocal formulation that does not involve spatial derivatives, and is a powerful tool to study defects such as cracks and interfaces.

Xuanhe Zhao's picture

A method to analyze electromechanical stability of dielectric elastomer actuators

      This letter describes a method to analyze electromechanical stability of dielectric elastomer actuators.  We write the free energy of an actuator using stretches and nominal electric displacement as generalized coordinates, and pre-stresses and voltage as control parameters.  When the Hessian of the free-energy function ceases to be positive-definite, the actuator thins down drastically, often resulting in electrical breakdown.  Our calculation shows that stability of the actuator is markedly enhanced by pre-stresses.

rajeshpnair's picture

discrete finite element method

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plesase help me to a model a 1D ballistic impact analysis problem  using discrete finite element method

rajeshpnair's picture

discrete finite element method

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i wish to model a one dimensional impact analysis using discrete finite element method.please give your sugestions

Jinxiong Zhou's picture

Propagation of instability in dielectric elastomers

When an electric voltage is applied across the thickness of a thin layer of an dielectric elastomer, the layer reduces its thickness and expands its area. This electrically induced deformation can be rapid and large, and is potentially useful as soft actuators in diverse technologies. Recent experimental and theoretical studies have shown that, when the voltage exceeds some critical value, the homogenous deformation of the layer becomes unstable, and the layer deforms into a mixture of thin and thick regions.

BoJing Zhu's picture

Mixed-mode flaws modelling at nanoscale in cell membrane system by time-domain hypersingular integral equation method

Cell membrane system has the protein-lipid-protein sandwich type structure. The membrane nanocomposites (PLP-MNs) typically exhibit pronounced nonlinear viscoplastic response under electro-thermo-elastic coupled incremental loads conditions.


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