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Optimal structural design against elastic instability


In the classical Euler buckling problem, the critical buckling load can be increased by a factor of four if the first mode is suppressed by placing an additional simple support at the mid-point.

If we solve the more general problem where the additional support is placed at some different point z=a in 0<z<L, the critical load will be found to increase above that for the unspported first mode, but the maximum increase is achieved when the support is at the mid-point and buckling then occurs of course in what would have been the second mode of the unsupported beam.

modelling of axisymmetric cold extrusion die by abaqus

 my problem is simulation of axisymmetric cold extrusion die. the die is conical, i have to determine die pressure, ram force and temprature in billet as well in die, plz see attached file and see simulation figure, my problem is same as in file,i have facing interaction problem in abaqus while solving this problem. plz help me

Mr

Hi friends,

I need to transfer stiffness and mass matrices from ABAQUS to Matlab. ABAQUS does generate matrices but those can be re-used by ABAQUS only. Is there a way to use these matrices in matlab. I know about SDT toolbox for matlab and I-MAT but they are costly.

Israr 

ground water table with no flow

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Dear all

 

How can I model the static ground water table (no flow) in soil using 3d ABAQUS ?

How to change the Navier equations for non-uniform Lame's constants

Hi Everyone,

                 I have to confess here that I do not have a mechanics background but I am currently working on a problem where i have to solve the Navier equation with non-uniform Lame constants of an object. If anyonme could guide me towards the necessary literature or  any other resource it would be very helpful. Sorry for any inconvenience.

cdeng's picture

A new paper on the nanoscale plasticity in twinned gold nanowires

A new paper titled "Enabling Ultrahigh Plastic Flow and Work Hardening in Twinned Gold Nanowires " from Dr. Sansoz's group just came out on the latest issue of NanoLetters. Attached below is the abstract and the full paper can be found at: http://pubs.acs.org/doi/abs/10.1021/nl803553b. We welcome any comment about this paper as well as our research.

Chaboche elasto-viscoplastic model with plastic strain memorization and time-recovery in ANSYS

Hi, I am a reserach fellow of mechanical engineering in Italy. I need to implement the elasto-viscoplastic model of Chaboche in a user subroutine in ANSYS accounting also for the plastic strain memorization and for the static and dynamic recovery. In a next step I sould also need to incorporate the damage variable of this model.

Phase Field Modelling of Fracture Mechanics

Hello To one and All,

 

I am currently working on my Master's thesis in Computational Mechanics and as the Title suggests, I am working on using phase field theories to model fracture mechanics. The whole idea /concept of phase field modelling in itself has been a very complex topic for me, as it originates in superconductivity theories of which I have but a superficial understanding. I am ok with fracture mechanics terminology as I have worked on it before.

 

Julien Yvonnet's picture

An XFEM/level-set method to model nanostructures

In the attached paper, we propose a procedure combining an XFEM/level-set technique and Gurtin-Murdoch surface elasticity to model nanostructures with arbitrary geometries. The effects of free surface which are dominant at small scales are easily captured in this framework.

Exact solutions for elastic half-space problems

Hi all

I am looking for exact solutions of deflection & stresses for the following problems:

1.    Elastic half-space loaded by a circular uniformly distributed load
2.    Elastic half-space subjected to a concentrated ring load

I found few journal papers, where reference was given to Timoshenko & Goodier.  But I could not trace the explicit equations for exact solutions of deflection & stresses for the above problems.

Calculation of natural frequency of beam

1. How to Compute the first three natural frequencies of vibration of cantilever beam?

2. How to Compute the first three natural frequencies of vibration of simple support beam?

3. What is Euler column formula?

fethi ABBASSI's picture

Composite thermoforming-ABAQUS

I need to modeling  an example of thermoforming of composite (woven PPS/ Carbone) on ABAQUS, which can help me (if possible to give me a tutorial)
thank you

Difference in vibrational characteristic of CNT in Thermal Environment

Can anybody suggets, (especially working in experimental field on CNTs ) whether there is any change in vibrational characteristics in CNTs subjected to temperature change.(especially in fundamnetal frequency values)

Mechanism To Increase Energy Efficiency.

 It is about using Cam for increase
energy efficiency. Cam are generally used to open and close valve of IC
Engine. I am going to show you another use. Left side initial position.
Right side final position. Redius of cam continuously decrease.Sliding
weight (MG) applied on Cam. With the help of rope weight(MG*Cos(b)) is
fixed with cam. We consider b as 45. So cos 45=.70. This fixed weight
should be 0.70 MG. Which balance the sliding weight applied on cam in
tengential direction. As sliding weight come down the fixed weight go

Equivalent Mass and Stiffness Distribution

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Hello everyone,

Mechanism To Increase Energy Efficiency.

View the figure attached. It is about using Cam for increase
energy efficiency. Cam are generally used to open and close valve of IC
Engine. I am going to show you another use. Left side initial position.
Right side final position. Redius of cam continuously decrease.Sliding
weight (MG) applied on Cam. With the help of rope weight(MG*Cos(b)) is
fixed with cam. We consider b as 45. So cos 45=.70. This fixed weight
should be 0.70 MG. Which balance the sliding weight applied on cam in
tengential direction. As sliding weight come down the fixed weight go
up. But the twist is the redius of cam decrease nominal continuously.
So sliding weight come down little bit and fixed weight go up much
more. We consider sliding weight come dowm H2 height and fixed weight

Arash_Yavari's picture

"Time variation of a fundamental dimensionless constant"

http://arxiv.org/PS_cache/arxiv/pdf/0903/0903.5321v1.pdf

The above article is an April Fool's joke. It reminded me of the recent "discoveries" in the mechanics community regarding stress tensor.

Regards,
Arash

Sigma_rr

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Sigma_rr

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FEA modelling with ABAQUS 6.6 of three roller Flow forming process.

Hi

this is Probal from university of western ontario (UWO). I am working on three roller flow forming process and i have to model the deformation specially in the splined area. could you please give me any idea or give any link so that i can have an idea what to do.

thank you probal 

References for Motion Groups

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I want to find a reference to learn about motion groups SE(N). Any recommendations will be appreciated. Regards, Deepak Trivedi

CYLINDERICAL PANEL

I AM DOING RESEARCH IN VIBRATION OF SOLID CYLINDERICAL PANEL CAN ANY ONE KNOWS THE EXACT DIAGRAM PLEASE HELP ME

Molecular dynamic simulations for carbon nanotubes

When using molecular dynamics simulations to study the variation of buckling strain versus aspect ratio of SWCNTs, is it necessary to keep the strain rate constant or displacement rate constant? Kindly appreciate your comments.

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