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Modeling a curved graphene sheet

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I'm trying to simlate the buckling behavior of a grpahene sheet using ANSYS APDL 14.5

In my analysis I need to have a graphene sheet that is curved with a variable radius for different cases. I was wondering if there is a faster way to model the graphene sheet assuming that the carbon-carbon bonds are modelled as elastic beam elements( beam 188) and the nodes are represnted by the carbon atoms.


 --Naveen R--

Buckling and Post buckling of Plates

Hello every one.

I'm doing work on buckling  analysis using abaqus. I want to continue my work on postbuckling of plates also. I'm not getting any tutorials on how to perform Postbuckling analysis of plates using abaqus. When i searched the abaqus help documentation, i got .inp file of a plate, but i didnt get the steps on how to perform the analysis. 

I read in some books that after buckling of a plate, it still can take the load. How to do this in abaqus interface ?how to perform the postbuckling analysis in a proper way ?

Plz help

Global buckling in a 3D beam ABAQUS

Hello everyone, 

I want to reproduce global buckling of a 3D column (simply supported) using shell elements independently of its length. 
I know that each section of the column should behave like a rigid body but I can't do it, so by doing the buckling analysis I get other buckling modes (like local buckling). 
My initial idea was to use rigid body (tie) constraint in some sections (uniformly spaced) but what I got was some local buckling in the extremities of the column. 

Bathe's subspace iteration, how to find the largest eigenvalue/mode?

Does anyone know how to modify Bathe's subspace iteration eigensolver to compute the highest eigenvalue instead of the smallest ?

Sung Hoon Kang's picture

Complex Ordered Patterns in Mechanical Instability Induced Geometrically Frustrated Triangular Cellular Structures

We have studied how complex ordered patterns can appear from buckling-induced geometrically frustrated triangular cellular structures.

The paper is selected as the Physical Review Letters Editors' Suggestion and highlighted in Physics Synopsis as the link below.


Intel MKL LAPACK SBGVX computes a few eigenvalues eigenvectors

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Anyone has an example using this subroutine ? 

I have implemented a test pgm as per user manual but i cannot get it to work.


conjugate real eigenvalues

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I have an eigenvalue solver, subspace iteration, that can get only positive eigenvalues. I have a problem (K - lambda M)u=0 that has pairs of eigenvalues +/- lambda. How can I transform the eigenvalue problem for the solver to search for lambda^2 rather than lambda?


Julian J. Rimoli's picture

Educational iPad app on structural mechanics

I would like to share with fellow mechanicians an educational iPad app I recently developed. The name of the app is Truss Me! and the main goal is to help students, all the way from high school to college, to build intuition on how truss structures behave. The video below highlights some features of the app:

rajnishmallick's picture

Buckling of an elastically restrained column

How to find a response for a pinned-(pinned+ torsion spring) column with sinusoidal axial load?

I am unable to decouple the equations in space and time using variable separable method, with one end pinned-other end pinned with torsion spring as boundary conditions.

Can anyone please help.

Good day.



Subspace Iteration eigenvalues and eigenvectors--efficient implementation?

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Anyone knows an efficient implementation of the subspace iteration method to compute a few lower eigenvalues and eigenvectors of a generalized problem KG*u=lambda*KS*u or any similar method? i.e., to compute the buckling loads and modes.

I'd like to use something optimized to Intel or amd64 processors or similar, like MKL, etc.

This is for bifurcation buckling analysis. KG is the stiffness matrix. KS is the geometric stress matrix. Both constructed from a FEM discretization.

Math Kernel Library MKL

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I want to use Intel Math Kernel Library (MKL) to calculate the bifurcation loads and modes in my custom FE program. MKL has many algorithms and I want to use the most efficient one.
Basically, I need to find a few eigenvalues lambda_i and eigenvectors u_i for the problem
KG * u = lambda * KS * u
where KG is the stiffness matrix and KS is the geometric stiffness matrix, also called stress-displacement matrix.
Is KG supposed to be positive definite?

Wave-like shape of a snake under parallel lateral constraints on a horizontal plane

Wave-like shape of a snake under parallel lateral constraints on a horizontal plane. The length of the snakes is 61+4 cm; the radius of the snake is 1 cm; the width between constraints is respectively 2, 3, 4, 5, 6 cm from (a–e). 

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Stephan Rudykh's picture

Wrinkling of Interfacial Layers in Stratified Composites

by Y. Li, N. Kaynia, S. Rudykh and M. C. Boyce

 Massachusetts Institute of Technology 



How to recover eigenvector components for specified displacements ?

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I have a problem visualising specified displacements from a modal/buckling analysis. 

When solving the algebraic system of equations [K]{u}={f} resulting from FEA discretization, the vector {u} does not have components for the specified displacements, zero or not zero, because the corresponding degrees of freedon (dof) have been eliminated. To visualize all the displacements, even the ones that are specified, we recover them from the input data to create a longer vector {u|u*} where {u} are the active dof and {u*} are the specified dof, zero or not zero. 

YongAn Huang's picture

Postbuckling analysis and its application to stretchable electronics

Dear all,

I would like to recommand a paper on "Postbuckling analysis and its application to stretchable electronics"。 Please find enclosed paper which is published on Journal of the Mechanics and Physics of Solids Vol. 60 (2012) 487–508.

susanta's picture

An atomistic-based foliation model for multilayer graphene materials and nanotubes

The mechanical behavior of mono- and multi- layered graphene and carbon nanotube (CNT) systems has attracted great attention over the last decade because of their importance in nano-science and nanotechnology.


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