buckling

Do you think this is correctly modeled as fork support (picture)

minor axis bending- restrained, torsion - restrained , free to warp

I am looking to model buckling of I steel beams with restraint in abaqus. But I do not know how to make rigid connections between the steel members. 

Why is the other beam( beam with fixed supports) not stressed? How do i define contact between the two beams.

hi everyone,

 i am doing my dissertation on buckling of channel section. so i have used abaqus software to do the analysis. i did the modelling and applided unit load n given pinned-pinned end condition. and i have used constraints to both ends such that the load applied on the edge is concentrated at a point .

but the results i.e mode shapes are not coming properly even the eigen values are very less compaired to calculated buckling load.

plz help me out. 

dimensions of specimen channel section

width of web 100mm

width of flange 50mm

HI,

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--

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

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

Anyone has an example using this subroutine ? 

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

Thanks.  

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?

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.

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?