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rajan_prithivi's picture

How are principal planes & eigen vectors of the stress tensor related ? | An intuitive explanation

To obtain the principal planes we construct the stress tensor and find the eigen vectors. Here is an attempt to explain it more intuitively rather than the use of the formal mathematical method. Hope you enjoy this video!

This is an educational outreach initiative targeted at all engineers interested in mechanics and seek simpler explanations. Kindly share if you learn something out of this !

Here is the link to the VIDEO

rajan_prithivi's picture

What are Principal Stresses (explained without math equations) ?


In the following video, I have tried to explain the concept of principal stress in a more physical way and without involving any mathematical equations, hope you can easily imbibe the concept.

Here is the link to the video : Principal stresses

rajan_prithivi's picture

Failure of brittle materials using simple experiments- Part 2

Here is my second video, where I tried to explain the concepts of stress state, principal stresses, Mohr circle and failure theories in layman's language and associated these concepts to explain the failure of a brittle material. This is an educational outreach initiative mainly targeted at the undergraduates (mechanical/civil/aerospace and materials engineering) studying mechanics and also other me

rajan_prithivi's picture

Concept of state of stress in a simple way

I tried to explain the concept of state of stress in a simple way, here is the link to the video - state of stress


Dear ALL,

Which reading material/source that describes the good understanding of stress triaxiality?

What is the role of stress triaxiality for FE analyst?

I have read a lot of papers/articles but still have confusing me on the fundamental of stress triaxiality.


How obtain tension strain concrete(σt0) in damaged plasticity model in ABAQUS?

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How obtain tension strain concrete(σt0) in damaged plasticity model in ABAQUS?

hello engineers

i need help about concrete damaged plasticity

fo example :

if Compressive stress (Fu)= 51.2 MPa

and tension stress (σ t)=0.3 x 51.2^(2/3)=4.136

1)why (σ t) is 2.36 in picture(uploaded)?

2)what is tension strain ? and how? i cant understand.

i cant obtain εt = total tensile strain.

how obtain εcr ?

please help


Carl T. Herakovich's picture

New Ebook on Elastic Solids at Amazon

This treatise provides a broad overview of the definitions of
fundamental quantities and methods of analysis for the use of solid materials
in structural components. The presentation is limited to the linear elastic
range of material behavior where there is a one to one relationship between
load and displacement.  Fundamental
methods of analysis and typical results for structures made of elastic solid materials
subjected to axial, bending, torsion, thermal, and internal pressure loading;

Jie-Hua Zhao's picture

Sr. Packaging Mechanical Analyst at Apple

 Sr. Packaging Mechanical Analyst

  • Job Number: 25557504 
  • Santa Clara Valley, California, United States
  • Posted: Jan. 3, 2013
  • Weekly Hours: 40.00

Job Summary

Mechanical engineer working in the central IC packaging group.

Key Qualifications

Mike Prime's picture

History of Bueckner’s principle?

I am hoping someone has some historical knowledge of some
interesting mechanics, or just an interest to discuss it. A superposition principle is widely used to solve crack problems, with illustrations like these:

how to find theoritically stress along thickness direction


      A composite 3D plate is subjected to tensile load and whilethe otherend is fully comnstrained. how to findstress along the thickness for theoritically

stress at interfacial Guass point

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stress at interfacial Guass point


     I have encountered a problem to calculate the stress at interfacial Guass point of each hexahedron element. Since the effective stress is needed to decide whether a cohesive element should be inserted when using the extrinsic cohesive element model, the stress at interfacial Guass point of each element is chosen to calculate effective stress. In the calculation process, the stress at Guass point of each hexaderon element can be obtained.Is there anyone who knows how to calculate the interfacial stress accurately? I would appreciate your comments.

surendran47's picture


how to do a crack propagation analysis?

can abaqus be used for doing crack propagation analysis for plates with multiple cracks?

Stress/strain of a body performing a translation

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. 

Lode Angle History?

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MRC Elsevier Distinguished Lecture, NJIT, Monday 18 April 2011

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

How to supply a visualization for the displacement gradient tensor

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.

Mohr's Circle---When Was the Last Time You Used It in Your Professional Engineering Work?

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:

Ahmad Rafsanjani's picture

Writing User Subroutines with ABAQUS

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

The Meaning of the Concept of Potential in Mechanics (and in Physics)

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.

Wondering about the Mechanics of Bacterial Death

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.

how to show the stress in the thickness direction when you use the shell element with abaqus


  •      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!


Producing Stress Analysis from Strain data

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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 it possible? I have access to Abaqus and Ansys, and where can i find the commands that allow me to do this.


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