In MEMS fields, a need arises in engineering practice to predict accurately the nonlinear response of slender post-buckling beams, especially the nonlinear transverse stiffness. The bistability of the post-buckling beams is excellent in reducing power consumption of micro-devices or micro-systems. However, the major difficulty in analyzing the post-buckling and snap-through response is the intractability of the geometric nonlinear control equations of large deflection beams.

http://dx.doi.org/10.1016/j.ijfatigue.2008.03.004

Hi, everyone

I just start my research on bounding surface model for soil mechanics. Does someone have documents about programming of bounding surface model for stress-strain behaviour with a piece of program? Thanks a lot for your help.

Fracture Mechanics,

CAE

 FEA

Crash Analysis

Hi, 

I must use user subrutine UEL in a Python script.

elemType1 = mesh.ElemType(elemCode=???, elemLibrary=???)
p.setElementType(regions=r, elemTypes=(elemType1, ))

what are the elemCode and elemLibrary that i must use????

 Thanks for help 

MD method is widely employed in different areas. However, as we all known that the limitation in timescales and length scales and the stiffness problem due to high frequency molecular vibrations are still important and difficult issues to be solved. While, characteristics of symplectic conservation is important for numerical methods. I found that only a few leteratures discussed this issue, and seldom new symplectic methods were widely adopted expect for the classical leap-frog Verlet  algorithm whose characteristics of symplectic conservation was proofed later.

I have several questios as fellows:

Which are the key issues of the development of MD?

Has someone worked on the parallel computing in the multibody system to the vehicle dynamics? It's what I am doing now. I am faced to make a choice, OpenMP or MPI? OpenMP is a little  easy to program, but with less portability. I prefer MPI and I think if it is a best choice to parallelize the constraint libraries, although it is a bit difficult to program. Am I right? Is anyone  also doing it now? Opinions and suggestions are welcome!

                            Xianfeng Ye 

I am a mechanical engineer in Turkey in senior year. As a graduation project I have to model soft tissue cutting operation by using ANSYS. The main aim in the project is;

1.Choosing
the correct material properties (SOLID,SHELL etc.) and correct
method( Prony Series or Generalized Maxwell for
viscoelastic)

2.Creating a cylindirical model as an example
and than creating the orginial model as a representation of the soft
tissue(in this case the tissue must be some living organ ex:liver )

3.By
using the contact modeling (I learned that it requires to have some
detailed experience in writing subroutine) dividing the material into

Dear colleagues,

The following is our most recent research work to share with you.  http://www.nature.com/nmat/journal/v7/n2/abs/nmat2085.html

Dear colleagues, 

  Here is our most rerent work to share with you!   http://www.nature.com/nmat/journal/v7/n2/abs/nmat2085.html

Is there any computing module which can compute a heap of disk elements in DEM(discrete element method)?it'd be better if it is written in matlab or C/C++. I'm doing research on the combined DEM-FEM. I need such module so as to save my time.

Thank you 

As the most rigid cytoskeletal filaments, microtubules bear compressive forces in living cells, balancing the tensile forces within the cytoskeleton to maintain the cell shape. It is often observed that, in living cells, microtubules under compression severely buckle into short wavelengths. By contrast, when compressed, isolated microtubules in vitro buckle into single long-wavelength arcs. The critical buckling force of the microtubules in vitro is two orders of magnitude lower than that of the microtubules in living cells.

hi all.

i'm not a researcher like allof you, i'm just a final year EEE student. i am seeking help for comparisons between iSIGHT and modeFRONTIER. if anybody can help i'ld be most grateful.

 thank you and good day.

I. Arias and M. Arroyo, Size-Dependent Nonlinear Elastic Scaling of Multiwalled Carbon Nanotubes, Phys. Rev. Lett. 100, 085503 (2008).

Size matters for the mechanics of multiwalled carbon nanotubes (MWCNTs). It has been known for some time that MWCNTs often wrinkle under deformation exhibiting the so-called rippling deformation pattern, which makes MWCNTs much softer. Through large-scale multiscale simulations we have characterized with a power law the softer wrinkled response, and showed that the transition strain between the super-stiff behavior attributed to MWCNTs and this softer regime scales as the inverse of the tube diameter. Thus, the tera Pascal Young’s modulus can be fully exploited in devices and materials only for moderately sized tubes. Similarly, in interpreting experiments or designing devices, the classical Euler-Bernouilli beam theory can only be applied to such tubes. The elasticity of thicker tubes is nonlinear, typically display mixtures of wrinkled and unwrinkled sections, and often exhibit hysteretic mechanical behavior.

See http://imechanica.org/node/2395 for a related post.

I am looking for specific research topics in applications of FEM in geotechnical engineering. It is just to gather some topics so as to pick the interesting one for my PHD.Anybody willing to share something on this? You can suggest any topic and of course few details will be helpful.

Cell tractions are the outcome of the complex process of cytoskeletal force generation that cell uses to maintain structural stability, to sense the physical environment and to propel itself.  We are only now beginning to understand the process of cytoskeletal force generation, and we cannot yet say much about the losses in transmission through focal adhesion/integrin complexes (attachment ‘islands’ at the cell-substrate interface), but we can definitely measure the tractions that result from cytoskeletal force generation.  The mechanics behind the measurement method might be of interest to the wider audience of iMechanica, as it involves an interesting inverse problem and different solution methods that have incited lively discussions in past years.

Study of wear in complex micro-mechanical components is often accomplished experimentally using a pin-
on-disc and twin-disc tribometer. The present paper proposes an approach that involves a computationally
efficient incremental implementation of Archard’s wear model on the global scale for modeling sliding and
slipping wear in such experiments. It will be shown that this fast simplistic numerical tool can be used to
identify the wear coefficient from pin-on-disc experimental data and also predict the wear depths within a
limited range of parameter variation. Further it will also be used to study the effect of introducing friction

We show that it is possible to distinguish between homogeneous and heterogeneous dislocation nucleation on the basis of differences in experimentally measured theoretical strengths. From nanoindentation tests, the critical shear stress for dislocation nucleation in two different Mo-alloy single crystals (Mo-3Nb and Mo-10Al-4Ni) is found to be ~1/8 of the shear modulus. The corresponding stress in uniaxially compressed Mo-10Al-4Ni micropillars is ~1/26 of the shear modulus. This strength difference is due to the higher critical stress required to nucleate a full dislocation loop homogeneously in the bulk as opposed to a half or quarter loop heterogeneously at a surface or edge. PRB 77, 060103(R), 2008.

Hi:

if you are familiar with the cartilage free swelling problem, you must have seen the boundray condition on cartilage-solution boundary where Mu=Mu*. Does this mean or imply that concentrations (or densities) of the components as well as the pressure on the boundary are the same as of those in the solution, i.e. does it mean that apparent density of water and ions are equal to the free solution and therefore are constant on the boundary. because that means the boundary is in equilibrium with solution and therefore the strain value on the boundary is set to zero.

Is that right?

Thank you,

Alireza

Hi everybody 

How do we use MSC-Marc finite element code to simulate the orthogonal metal cutting process? Is there anybody having example or tutorial about that?

best wishes

kubilay 

I want to mesh a 3D surface given as an implicit equation into triangle elements. For example, cos(x)+cos(y)+cos(z)+0.2=0 with -pi<x<pi, -pi<y<pi,-pi<z<pi. Is there any software can do it?

Size effects at initial yield (prior to Stage II) of micron sized specimens are modeled within a continuum model of plasticity. Two different aspects are considered here: a) specification of a density of dislocation sources that represent the emission of dislocation dipoles, and b) the presence of an initial, spatially inhomogeneous excess dislocation (ED) content. Discreteness of the source distribution appears to lead to a stochastic response in stress-strain curves, with the stochasticity diminishing as the number of sources increases.

We enhanced a bi-layer fiber-matrix microstructural arterial model with softening and analyzed the artery inflation under the internal pressure. Numerical simulations lead to the following three findings. Firstly, it is found that the fiber strength dominates the strength of the media layer. Secondly, it is found that the strength of the media layer dominates the overall arterial strength and plays the crucial role in the load-bearing capacity of arteries. Thirdly, it is found that residual stresses can increase the overall arterial strength significantly. The pre-existing compression in arteries delays the onset of rupture like the pre-existing compression in the pre-stressed concrete delays the crack opening.

Dear, I use the abaqus present , how can apply a tightening torque between an implant (screw) and the bone with abaqus......... thank you ¶