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Shell 99 in Ansys


 I'm attempting to model a thin composite laminate plate in ansys and after searching this website and using the ansys help, I have chosen to use shell 99. However when I load up the Ansys 8.0 software on the university computers (I am a student), I can not seem to find the Shell 99 choice, or in fact any of the other possibilites, such as shell 91, shell181, solid 46, or solid 191.

 Just wondering if anyone would know why this is the case, I'm hoping that it;'s not because it's a university edition or something.


Cheers for the help. 

force on dislocations

Hi, how the Peach-Koelher force acts on a dislocation?, I understand when the resolved shear stress acts on a dislocation. But not quite the term that provokes  climb on an edge dislocation...

Mechanical impedance for a cantilever euler beam


I have a cantilever Euler beam with a force.

I want to find mechanical impedance for this system

Can you hel me for Specify this impedance?

I attach a jpg file that it show my system. 


How to do node separation in ABAQUS by giving shear failure

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 i am working in abaqus for chip formation in machining by using shear failure..please help me how to proceed

How to node separation in ABAQUS by giving shear failure


 i am working in abaqus for chip formation in machining by using shear failure..please help me how to proceed

Neo Hookean Model

I am modeling a RBC(red blood cell) membrane using shell181 element and
using neo hookean model. But when I try to solve it, it gives error. I
couldnt figure out the cause. Please help me.
This is my input file for creating the model.

triangular load on an area



I try to enter a triangular load on an area. I have entrered the gradient information in settings. But when I try to apply load on area, it does not take it in triangular form, but in constant form. It works  with apply on nodes. But, is the result correct with this option?

Deflections for continuous beams


  hi all,

     how  the deflection of continuous beams are evaluated by using Rayleigh-Ritz method?

Huapei Wan's picture

Pressure on circular area of a semi-infinite plane: typos in textbooks "contact mechanics" "surface mechanics" "elasticity"

This is supposed to be a very classic analytical solution in applied elasticity. Forgive me if this is a repost or some correction has been made before. I had a hard time with it.

Problem statement:  uniform pressure is applied on cirular area (radius=r) on top of a semi-infinite plane. Find the vertical deflection.

We got discrepancy between FEA solution and analytical solution which I found from different textbooks (famous and non-famous): Deflection within the circle is good, however, no good outside the circle.

We found the correct solution is attached.

ANSYS shell99

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Does anyone knows what's the theory of the element shell99 in Ansys? I tried to search in ANSYS Help, but didn't find anything. Is it kirchoff classical plates theory?

Pond design

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. I want to design a detention pond, where should I start? The flow into pond is 1.4m3/s, the existing SW system near the pond is 600 dia pipe. If I calculate the disharge through the pipe using Mannings formula, the max capacity is 1.8m3/s, using the orifice formula for 600 dia pipe it is only 0.5m3/s. So which one should I use? Because if it is orifice one I will need to allow for 3m head water

abaqus cae

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Hi guys..i am an abaqus CAE user and i am creating a model of an annular disc with a clamped at the middle hole. I have to compare the result of the stationary one with the rotating one. But I did not know the command for a rotating disc, as I have tried, I used the rotational body force. The problem is the result is the same as the stationary one which is wrong! i am a beginner at this, so could somebody help me out here, please?


Solids Textbooks

      The texts from Timoshenko and Landau and Lifschitz are classics. I think learning the physical approach of L&L is particularly valuable. The following sections are available in L&L:

 1. Fundamental Equations

 2. Equilibrium of Rods and Plates

3. Elastic Waves

4. Thermal Conduction and Viscosity in Solids

Look for insightful physical explanations, and expect to read with a pen and paper at your side, to understand exactly the brilliance behind each statement made.

Indentation test modelling on Ansys

I am currently doing simulation on Ansys regarding the indentation test for viscoelastic material. I have some problem with the contact element.. Can someone help me on?

Crack tip stress and formation of Plastic/influence zone for composite solid rocket propellant

Crack tip stress and formation of Plastic/influence zone for composite solid rocket propellants

The necessity to understand the crack behaviour of composite solid rocket propellants as it helps in analysis of service life of rocket motors. Experimental data reveals that a material’s microstructure at the crack tip can have a significant effect on the local damage near the crack tip and crack growth behaviour in particulate composites. 

shear stress distribution in nanotubes

Taxonomy upgrade extras: 
David J Unger's picture

J-Integral Elliptical Hole (Plane Stress) Perfectly Plastic Material

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The fracture mechanics community may be interested in a new evaluation of a J-Integral for a fundamental geometry:  an elliptical hole in a perfectly plastic material under the Tresca yield condition for plane stress loading conditions. The analysis is exact and involves only elementary functions.  This makes the problem suitable as a classroom example or as a homework problem for a graduate level course in fracture mechanics.  See J. Elasticity (2008) 92:217-226.

Post Buckling of Thin Shells

It is difficult to conduct post buckling analysis of thin shell under axial compression using Arc Length method in Ansys.
The Minimum & Maximum Arc Length radii are chosen by hit & trial.When imperfections are incorporated in the FE model,  some times the solution diverges at a higher critical load that the eigen value  buckling, which should be vice versa in actual. Some times , negative eigen values are also shown.

Is there any easy way to solve this nonlinear stability problem?


What is the meaning of nonhardening Material

I am getting confused with a definition of nonhardened Material as I read the book Fracture Mechanics written by T.L. Anderson.
I got two understandings and am not sure which one is right.
1)    Material with lower yield strenth, which was not work-hardened.
2)    d(stress)/d(strain) = 0 after yielding.


(All my simulations and research is conducted under guidance of respected Dr. Henry Tan, Uni. of Manchester)


Konstantin Volokh's picture

Nice and low-cost introductory texts

There are two very nice companion texts on continuum mechanics and nonlinear elasticity printed by Dover recently: "Continuum mechanics" by Spencer and "An introduction to the theory of elasticity" by Atkin and Fox. Great and fairly affordable reading!


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