FEM

I have some problems with my matlab code in a 9 node shell
element each node has 5 DOFs. I found that stiffness matrix for each
element is symmetric, but after transformation to global coordinate
system, the transformed stiffness matrices and the resulted global
stiffness matrix of entire shell is nonsymmetric, where order of
transpose([k]) -[k] is approximately E-18.

Mass matrix also has
been antisymmetric after transformation and so I can't solve
characteristic equation to find eigenvalues needed for dynamic analysis.

Hi all ... Is there a way to find/calibrate material parameters for johnson and cook material model using experimental data in Abaqus? .. As far as i know abaqus has something called as data editor with which Hyperelastic materials models can be calibrated with experimental results. If not is there any other way arround to do calibration of material parameter with abaqus.

As a consultant in computational mechanics, I currently help write some FEM-related code, and while doing this job, an episode from a recent past came to my mind. Let me go right on to the technical issue, keeping aside the (not so good) particulars of that episode. (In case you are curious: it happened outside of my current job, during a job interview.)



If you are a design engineer, FE analyst, researcher, or any professional dealing with stress analysis in your work, I seek answers to a couple of questions from you:





Question 1:

On friday we had a wonderful trip to Modena, at the University of Modena's Millechili
Lab with which I collaborate also for the MilleChili journal Millechili Journal -- weight reduction in vehicle design.
In collaboration with Ferrari SpA project.

Hi,

I hope this is the right forum to get some help for my work. 

I am looking at CT data (DICOM files) to make FEM models. To generate 3D surface/volumes for FEM, I was looking for softwares. They all are pretty expensive (4-10K USD). I have decide togo with Able Software's 3D-DOCTOR. I am lookign for some reviews or user experience or comments for this tool.

Thanks

Prab

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.

In this manuscript (available at http://arxiv.org/abs/1004.1765), we present a systematically improvable, linear scaling formulation for the solution of the all-electron Coulomb problem in crystalline solids. In an infinite crystal, the electrostatic (Coulomb) potential is a sum of nuclear and electronic contributions, and each of these terms diverges and the sum is only conditionally convergent due to the long-range 1/r nature of the Coulomb interaction.