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mortezaamjadi's picture

Carbon Nanotubes-Ecoflex Nanocomposite for Strain Sensing With Ultra-High Stretchability

We developed highly stretchable, flexible and very soft conductors based on the carbon nanotubes (CNTs)-silicone rubber (Ecoflex®) nanocomposite thin films. The resistance of the CNTs-Ecoflex nanocomposite thin film was recovered to its original value under cyclic loading/unloading for strains as large as 510%. Failure strain of the CNTs-Ecoflex nanocomposite was measured to be about ~ 1380% showing its ultra-high stretchability and robustness. As an application of our highly stretchable conductors, we utilized them as skin-mountable and wearable strain sensors for human motion detection.

mortezaamjadi's picture

Flexible and Sensitive Foot Pad for Sole Distributed Force Detection

In this work, we develop high flexible and compressible porous PDMS structures by using sugar cubes as templates. Force sensitive resistor (FSR) sensors were fabricated by the filtration of the CNT solution inside the porous structure of PDMS. We found that sufficient acid treatment can increase the adhesion between CNTs and PDMS. FSR sensors respond the applied pressure and compressive strains by high linearity (R2>0.97) and sensitivity (GFs>2) with a reliable manner.

Z-mat files in ABAQUS

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I am trying to figure out how to incorporate Z-mat files in ABAQUS to simulate complex constitutuve models of polymers. While I have worked with UMAT subroutines before Z-mat is something new. Can somebody explain why Z-mat is necessary and are there any differences between conventional UMAT/VUMAT and Z-mat files?



Title: Effect of Hygrothermal Aging on the Mechanical Properties of Fluorinated and Nonfluorinated Clay-Epoxy Nanocomposites

Polymers absorb moisture due to their hydrophilicity. Absorption of moisture changes the functional, mechanical and chemical properties of the polymer. Since polymer based materials are being increasingly used for structural applications, its only fitting to investigate how moisture absorption translates to mechanical property change. This experimental study investigated the effect of moisture absorption on the mechanical properties of epoxy polymers and their clay nanocomposites. Previous research studies reported that the high aspect ratio of clay slowed down the absorption rate.

Giorgio Carta's picture

Dispersion properties of vortex-type monatomic lattices

The paper presents a systematic study of dispersive waves in an elastic chiral lattice. Chirality is introduced through gyroscopes embedded into the junctions of a doubly periodic lattice. Bloch-Floquet waves are assumed to satisfy the quasi-periodicity conditions on the elementary cell.

M. Shaat's picture

Pull-in instability of multi-phase nanocrystalline silicon beams under distributed electrostatic force

The effects of the material structure on the pull-in instability of nano-actuated beams made of nanocrystalline silicon (Nc-Si) and subjected to a distributed electrostatic force are investigated. Nc-Si is represented as a multi-phase material composed of nano-sized grains, nano voids, and an amorphous-like interface to consider the effects of the interface, grain size, porosity, and the inhomogeneities surface energies on the elastic properties of the composite material.

M. Shaat's picture

Modeling of mechanical resonators used for nanocrystalline materials characterization and disease diagnosis of HIVs

The modeling and performance of mechanical resonators used for mass detection of bio-cells, nanocrystalline materials characterization, and disease diagnosis of human immune-viruses (HIVs) are investigated. To simulate the real behavior of these mechanical resonators, a novel distributed-parameter model based on Euler-Bernoulli beam theory is developed. This model is equipped with a micromechanical model and an atomic lattice model to capture the inhomogeneity nature of the material microstructure.

M. Shaat's picture

Effects of grain size and microstructure rigid rotations on the bending behavior of nanocrystalline material beams

Due to the intensive decrease in grain sizes of nanocrystalline materials (NcMs), a large volume fraction of atoms reside in the interface regions between crystals forming an atom-cloud phase with a distinct atomic structure. Moreover, the surface to volume ratio of the grain increases, thus its surface energy will significantly affect the mechanical properties of NcMs.


M. Shaat's picture

Iterative nonlocal elasticity for Kirchhoff plates

Recently, the nonlocal elasticity theories have been used in studying the different behaviors of micro/nanostructures. However, there is a complicity in applying the natural boundary conditions in the context of the nonlocal differential elasticity models. Also, the nonlocal integral elasticity could provide a suitable remedy for this type of problems but with paying highly computational efforts.


M. Shaat's picture

Physical and Mathematical Representations of Couple Stress Effects on Micro/Nanosolids

In the present paper, for linear elastic materials, effects of couple stresses on micro/nanosolids are physically discussed and mathematically represented in the context of the classical, the modified and the consistent couple–stress theories. Then, an evaluation is provided showing the validity and the limit of applicability of each one of these theories. At first, the possible couple stress effects on mechanics of particles and on continuum mechanics are represented.

Inverse distance weighting as a FEM shape function

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Hello there!

I was thinking to use inverse distance  interpolation technique as a finite element shape function. However, I am not sure about its performance for finite element method, inverse distance interpolation was originally developed for geographic information system.

can anyone help me please?

thanks in advance!

Arash_Yavari's picture

A new paper on Hencky-logarithmic strain by Prof. Neff

Dear Colleagues:

I thought the following recent paper by Prof. Neff may be of interest to some of you.

This paper discusses the natural appearance of the  Hencky-logarithmic strain tensor together with the Hencky strain energy, which can be motivated from some purely geometrical (kinematical) arguments based on the geodesic distance on the general linear group of all invertible tensors GL(n).

Frank W. DelRio's picture

Fracture strength of micro- and nano-scale silicon components

Silicon devices are ubiquitous in many micro- and nano-scale technological applications, most notably microelectronics and microelectromechanical systems (MEMS).  Despite their widespread usage, however, issues related to uncertain mechanical reliability remain a major factor inhibiting the further advancement of device commercialization.  In particular, reliability issues related to the fracture of MEMS components have become increasingly important given continued reductions in critical feature sizes coupled with recent escalations in both MEMS device actuation forces and harsh usage

Link Ansys with Matlab

I want to do optimisation in Matlab by linking it to Ansys.

I need to get my graph from Ansys in each itteration and import the graph in Matlab in order to compare with experimental results and get new coefficients. These coefficients again needs to import in Ansys file.


I could manage to do it with smaller size file (with less degree of freedom), but when it comes to complicated geometry with more nodes and elements number, I got liscence problem. It looks like there is a limitation in running when you call Ansys from Matlab.


mortezaamjadi's picture

Sensitive and stable strain sensors based on the wavy structured electrodes

Herein, we develop capacitive type strain sensors composed of the CNTs-PDMS nanocomposite thin films as electrodes and PDMS dielectric layer. The strain sensing performances of the strain sensors made of the flat and wavy structured electrodes are compared. Both types of strain sensors can measure strains up to 100%. We found that wavy structured based strain sensors possess higher sensitivity with quite stable and reliable responses due to the resistance stability and very low resistance standard deviation of the wavy structured electrodes.

mortezaamjadi's picture

Ag@Ni Core–Shell Nanowire Network for Robust Transparent Electrodes Against Oxidation and Sulfurization

Silver nanowire (Ag NW) based transparent electrodes are inherently unstable to moist and chemically reactive environment. A remarkable stability improvement of the Ag NW network film against oxidizing and sulfurizing environment by local electrodeposition of Ni along Ag NWs is reported. The optical transmittance and electrical resistance of the Ni deposited Ag NW network film can be easily controlled by adjusting the morphology and thickness of the Ni shell layer.

mortezaamjadi's picture

Highly Stretchable and Sensitive Strain Sensor Based on Silver Nanowire–Elastomer Nanocomposite

The demand for flexible and wearable electronic devices is increasing due to their facile interaction with human body. Flexible, stretchable and wearable sensors can be easily mounted on clothing or directly attached onto the body. Especially, highly stretchable and sensitive strain sensors are needed for the human motion detection.

ansys *do

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DK,200, , w , ,0,UY, , , , , ,

DK,201, , w , ,0,UY, , , , , , 




This is a do loop in ansys apdl. I expect w to change every loop. However output window says i is an unknow parameter. Does anybody know what the problem is? 

dithoap's picture

Measuring damage variables from load-unload test (damage mechanics)

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Hi All,

I want to use ductile damage model in ABAQUS to model the damage of thermoplastic polymers, in which I need to input the damage evolution law (\dot{d}).

My question is on the way we have to measure the variable d.

Suppose I have 10 cycles of load-unload test. For slope of the first load will be initial Young's modulus at undamaged state E_0. now for the next cycle, which part of the curve we need to measure their slope to get the damage variable (d = 1 - E/E_0).

Yonggang Huang's picture

Median Review Time of all ASME Journals

I attended an ASME meeting during which the Managing Director of ASME Publishing reported on the ASME publications. 


Giorgio Carta's picture

Temperature induced crack propagation in structured media

This paper describes the propagation of an edge crack in a semi-infinite triangular lattice, consisting of identical point masses connected by thermoelastic links. A change of temperature, represented by a time-periodic series of high-gradient temperature pulses, is applied at the boundary of the lattice. In order to make the initial crack advance in the lattice a failure criterion is imposed, whereby the links break as soon as they attain a prescribed elongation.


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