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# eigenvalue

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

Wed, 2014-03-12 16:03 - EchebanDoes anyone know how to modify Bathe's subspace iteration eigensolver to compute the highest eigenvalue instead of the smallest ?

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## Math Kernel Library MKL

Mon, 2013-10-14 18:08 - EchebanI 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?

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## Bifurcation Analysis in Abaqus

Wed, 2013-08-21 13:36 - AliADawoodHello Everyone,

Im relatively new to Abaqus and I have to carry out a bifurcation analysis of a pipe. Once that is done I need to add the imperfection wavelength and amplitude calculated to the pipe and carry out further simulations.

Ive been trying very hard to get a direction as to where to start with it. Can anyone please help me with it? I know that you need to carry out a buckle analysis that will give you a wrinkle pattern on the pipe. This inturn will add up to the bifurcation scheme that you get.

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## Wanted: Fast FEA Solvers...

Fri, 2010-05-14 10:18 - Ajit R. Jadhav
**Summary:**

I am thinking of informally conducting a specific case-study concerning the FEA solvers. The reference problem is a very simple but typical problem from stress analysis, leading of course to the linear systems: Ax = b and Ax = Lx.

I seek advice as to what software libraries currently available in the public domain would be best to use---the ones that would be fastest in terms of execution time for the reference problem.

I have a personal and longer-term research interest with certain issues related to the solvers technologies.

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## bifurcation buckling using ABAQUS

Thu, 2009-04-30 15:57 - ranababu

The following is taken from the book Concepts and applications of Finite element methods by Cook, Malkus and Plesha.

For bifurcation buckling, we have the following eigenvalue problem:

(K+Lambda Ksigma)delta d= 0

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## principal directions for 4th order tensor

Fri, 2009-02-13 11:12 - whitmanIs it possible to find eigenvalues and principal directions for a 4th order tensor? How?

For a zero order tensor? for a first order tensor? for a third order tensor.........

many thanks

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## Find eigenvalues of the coupled differential equations by Finite Difference Method.

Fri, 2007-06-08 07:55 - lqkhaiHello everybody,

The coupled differential equations need to solve as following:

Could you help me to discretize this systems and find the eigenvalue λ numerically using finite difference method?

Thanks in advance,

lqkhai

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