Hello all,

I am having task to determine the strength analysis (stress/strain) of a translating machine part (body). The part is driven by a set of gears, placed on the top of the body. The input is a constant acceleration value to the propultion engine. Firstly I should do a 2D analysis with a retangle representing the machine part. 

I am new to this subject, so any idea, approach,  advice or helping material is welcomed. 

All,

In my research, I have been using the Lode angle of the stress tensor in a fracture model. Consequently, I've been reading up on the Lode angle and have found that just about each publication defines their own Lode angle that is slightly different from everyone else. So, I've searched around to find out the history of the Lode angle, but have come up empty-handed. I would imagine that the Lode angle is named after some Mr. Lode, but I cannot even find his first name. Do any of you know where, when, or who came up with the idea of the Lode angle? Particularly, I would like to get a copy of the first publication, if you happen to have one or know where one might be.

Thanks,

Scot Swan

Elsevier is pleased to announce that Professor Sia Nemat-Nasser will be presenting 'Managing Stress Waves Over Multi-frequencies by Micro-architectural Design of Materials', the Mechanics Research Communications Elsevier Distinguished Lecture (sponsored by Elsevier and the New Jersey Institute of Technology Granular Science Laboratory). The lecture will take place in the Guttenberg Information Technologies Center, NJIT, on Monday April 18, 2011, 11:30 a.m. - 1:00 p.m. Full details are available at

http://www.elsevier.com/framework_products/promis_misc/mrclecture.pdf

Hi all, 

[Warning: The writing is long, as is usually the case with my posts :)]

It all began with a paper that I proposed for an upcoming conference in India. The extended abstract got accepted, of course, but my work is still in progress, and today I am not sure if I can meet the deadline. So, I may perhaps withdraw it, and then submit a longer version of it to a journal, later.

What is stress? Who has ever seen stress? Is stress a physical quantity?

Professor Yi-Heng Chen, Xi’an Jiaotong University, 710049, P.R.China

e-mail: yhchen2@mail.xjtu.edu.cn

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:

Hi all,

  I have few questions here :  

1.From my reading i  can understand there is a long debate going on stating Hydrostatic Stress (HS) have/have not influence over yielding and failure of materials. Some people say when only HS is applied the material become 'incompressible' and the HS donot influence yielding. Some people say when the material is porous the HS load do have influence in yielding as there is room for deformation when the pores collapses. To add more confusion some say even the material is not porous HS have influence over yielding. Someone please throw some light on these arguments and which one is true?

Dear All,

 I think that many students are looking for some tutorials about writing a UMAT in ABAQUS.

You can find a comprehensive tutorial for elastic problems.

This file contains: 

• Motivation

• Steps Required in Writing a UMAT or VUMAT

If someone knows of books/articles dealing with the meaning of the concept of potential in physics (or concerning the physical bases underlying the energy methods of mechanics) then I would very much appreciate getting to know about these.

0. I was idly thinking about the current H1N1 flue pandemic, and the following things occurred to me. Please note, I know very little about this subject matter. So, please consider descriptions in the following as, at best, tentative.

1. There is a basic difference between how alcohol kills viruses and how salt-water kills bacteria. [Alcohol is used in the hand-cleaners they use in hospitals. Girgling with salt-water is the first line of defense (and an unexpectedly highly effective one) which is well known for millenia.]

But the mechanisms involved are different.

hello,

•      i simulate some process using shell elment, i find the results have big difference between abaqus and lsdyna. the abaqus results always show the stress in the thickness direction is zero. but the lsdyna is not. i don't know why? if some one know that, please give me some suggestions. i heard that the abaqus can not show that stress component. if not, how can i do to calculate that and fill it into the results file (.fil file). thank you!

I am doing research on the stresses that are produced when a retainer (a thermoplastic sheet) is placed on the teeth. We've designed the project so that we take an initial scan of the sheet and a final "shifted" scan of the sheet. We'd like to compare, find the strain, and calculate the stress neccessary to produce this strain.

I was hoping to use FEA for this...is it possible? I have access to Abaqus and Ansys, and where can i find the commands that allow me to do this.

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. 

I was browsing the discussion page for Stress in Wikipedia when I came upon this interesting comment:

"

Refutation of Cauchy stress

The theory of stress based on Euler & Cauchy is now refuted. The profound incompatibility of this theory with the rest of physics, especially the theory of potentials and the theory of thermodynamics, has been documented in

In between stress and strain, which one is the more fundamental physical quantity? Or is it the case that each is defined independent of the other and so nothing can be said about their order? Is this the case?

To begin with these questions, consider the fact that first we have to apply a force to an object and it is only then that the object is observed to have been deformed or strained. Accordingly, one may say that forces produce strains, and therefore, it seems that stress has to be more fundamental. If so, how come stress cannot be measured directly? This is the paradox I would like to address here.

Of course, to begin with, my position is that you can never directly measure stress.

I just came across the lecture notes from Professor Nix on Mechanical Properties of Thin Films. It is very educative and helpful. I wonder if anyone could recommend some analytical derivation on the stress of the adhesive layer between two similar/dissimilar adherends (sandwiched specimen) under mechanical or thermal loading.

Many thanks ...

Augustin Louis Cauchy ( 21 August 1789 - 23 May 1857) was a French mathematician and mechanician. In mechanics, he in 1822 formalized the stress concept in the context of three-dimensional thoery, showed its properties as consisting of a 3 by 3 symmetric arrays of numbers that transform as a tensor, derived the equations of motion for a continuum in terms of the components of stress, and gave the specific development of the theory of linear elasticity for isotropic solids. As part of his work, Cauchy also introduced the equations which express the six components of strain, three extensinal and three shear, in terms of derivatives of displacements for the case when all those derivatives are much smaller than unity; similar expressions had been given earlier by Euler in expressing rates of straining in terms of the derivatives of the velocity field in a fluid. (cited from Mechanics of Solids by J.R. Rice) Read more...