iMechanica - Forum topic - Comments

a concrete frame modelling in ansys

mobini.mh — Sun, 07 Feb 2010 05:25:18 -0500

Hi dear friend,

I'm a beginner in ansys,and in my thesis I have to simulate a concrete frame,so I want to know do you have any ansys example which could help me?

thanks a lot

M.H.Mobini

mathematical theory of homogenization applies

Henry Tan — Sat, 06 Feb 2010 15:59:00 -0500

Nachiket,

Thanks for the references of Hassani and Hinton’s three-part review.

The mathematically defined cellular materials shown in my figures above have a periodic base cube of [0,Pi]X[0,Pi]X[0,Pi]. The whole domain of the cellular material comprises a uniform cell structure.

Therefore, the mathematical theory of homogenization, for the computation of effective constitutive parameters, outlined in the part I applies to the current case. FEM is needed only for the calculations in the base cube.

Regards,
Henry.

Henry, I was thinking of a

Nachiket Gokhale — Sat, 06 Feb 2010 12:35:08 -0500

Henry,

I was thinking of a numerical analysis based on the two scale homogenization theory reviewed in Hassani and Hinton ( a three part review):

http://dx.doi.org/10.1016/S0045-7949(98)00132-1

The link points to one of the parts. I was hoping that an analytical solution could be done like the authors do in the first part for relatively simple microstructures, but it seems that FEM based homogenization is most appropriate.

-Nachiket

mathematically defined cellular materials

Henry Tan — Sat, 06 Feb 2010 08:45:13 -0500

Nachiket,

To my knowledge, there is no analytical homogenization study for these kinds of mathematically defined cellular materials.

The stress distribution for a single period element seems cannot be analytically obtained. This is the major difficulty that blocks the advancement.

However, at least we can do some numerical analyses on these problems as the initial try. Are you interested in doing that together?

Regards,
Henry.

Hi, Thanks for the

shrimad — Fri, 05 Feb 2010 18:38:37 -0500

Hi,

Thanks for the reply. That clears it up. I was thinking about the same thing, but wasn't sure.

However, let's say the nodes are not coincident and are being used by both the bodies (the common node). Now, if that node is constrained fully as a rigid node (all disps = 0), in that case there will be no interdependence as the stiffnesses because of the constraint will not be in effect for both the bodies. Am I thinking right?

Shriram

analytical homogenization

Nachiket Gokhale — Fri, 05 Feb 2010 14:35:15 -0500

Henry,

This is very nice. Has anyone performed any analytical homogenization studies using such equations to describe the microscale?

Thanks,

-Nachiket

magic equations

Henry Tan — Fri, 05 Feb 2010 10:47:00 -0500

Equation:
sin(x)*cos(y)+sin(y)*cos(z)+sin(z)*cos(x) - 1.3 < 0
describes a cellular material like

Equation:
sin(x)*cos(y)+sin(y)*cos(z)+sin(z)*cos(x) - 0.3 < 0
describes another cellular material like

Anil Kumar Narwal Assistant

narwal_anil — Wed, 03 Feb 2010 22:45:01 -0500

Anil Kumar Narwal
Assistant Professor
TIT&S, Bhiwani
India

verification

Henry Tan — Wed, 03 Feb 2010 16:08:00 -0500

"Peridynamics theory works very well even if there is no discontinuity in the structure."

Are there any papers published so far that verify the peridynamics theory with analytical solutions exist for comparison?

Hi Karthikeyan, I'm

Viet-Tung NGUYEN — Wed, 03 Feb 2010 10:03:28 -0500

Hi Karthikeyan,

I'm using Radioss and Pamcrash for composite's impact analysis at work. I'm experienced in using LS Dyna but never try doing composite's modeling with it. Nevetheless the principle must be the same: you need to define the composite layup then the materials characteristics. For crush modeling we use a composite behaviour that taken into account dammage and rupture behaviour in fiber and matrice (direction 1 and 2) and delamination. The difficulty is obtaining physical parameter for your materials (yield stress in tension, compression in each direction, yield strain in tension, compression in each direction, delamination shear stress ...). Then you have to decide that the element is eliminated by failure in each ply or in all ply. I hope that can help. If you have a dyna file with composite materials, i can have a look and try to fix it.

Regards

Thank you for the information

sivaprasad.avs — Wed, 03 Feb 2010 02:04:08 -0500

Sir,

Thank you for the information and the paper.

Stress triaxiality

Kejie Zhao — Tue, 02 Feb 2010 13:14:36 -0500

Stress triaxiality denotes the ratio of hydrostatic stress and Von-mises stress. This might be in some textbooks, or with google, I find the following paper

On the Application of Stress Triaxiality Formula for Plane
Strain Fracture Testing. J. Eng.
Mater. Technol. 2002

Hi Tolly, Could you

karun — Tue, 02 Feb 2010 13:04:51 -0500

Hi Tolly,

Could you please send me Windows glass data.

Thanks in advance.

--------------------------------------------

Arun Upadhyay

Department of Materials Science and Engineering
University of Michigan

Summary of the 9th week discussions

Henry Tan — Mon, 01 Feb 2010 06:54:49 -0500

Here is a summary of the discussions in the 9th week since the launching of this forum.

The discussions were with Erkan Oterkus about several papers of Silling et al.

R. W. Macek and S. A. Silling, "Peridynamics via finite element analysis," Finite Elements in Analysis and Design, Vol. 43, Issue 15, (2007) 1169-1178.

S. A. Silling, M. Epton, O. Weckner, J. Xu and E. Askari, "Peridynamic States and Constitutive Modeling," Journal of Elasticity, Vol. 88 (2007) 151-184.

S. A. Silling and E. Askari, "A Meshfree Method Based on the Peridynamic Model of Solid Mechanics," Computers and Structures, Vol. 83 (2005) 1526-1535.

Silling, S. A. (2000). "Reformulation of Elasticity Theory for Discontinuities and Long-Range Forces". Journal of the Mechanics and Physics of Solids , Vol 48: 175–209.

Dear Mr. YangTang, if

Pato80 — Mon, 01 Feb 2010 06:07:12 -0500

Dear Mr. YangTang,

if you will be using Finite Element Method to study this kind of problem, I can advice you to use this software:

SAMCEF for Fracture Mechanics.

The company that developes this particular CAE application is SAMTECH (from Belgium).

Hope it helps,

Best regards,

Patrizio