Hello everyone, I am studying the dynamic crack initiation problem of composite material. Just like the below imagine ,a crack perpendicular to the interface of two different materials, under dynamic load, the crack will propagate, at the crack tip I use the singular element to simulate the stress and strain state. after I have the crack tip stress, how can I calculate the energy release rate of different direction, for example, also along the original crack line or perpendicular to the original crack line., or kink from the 45 degree of original crack line.

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Hello everyone,

 Why do we have the infinitesimal (linear) strain tensor to be symmetric? The reasons, which I have understood so far are:

1. It is defined to be symmetric so that it behaves like a tensor.

2. The stress tensor, which is its energy conjugate, is symmetric, and hence the skew-symmetric part has no contribution towards strain energy.

 Can anyone suggest more fundamental reason(s) for the symmetry of linear strain tensor, like the moment equlibrium leading to symmetry of the Cauchy stress tensor?

Thanks in advance,

Hi everyone, 

Sometimes while replying for the answered queries, I face the issue of "COMMENTS FIELD IS REQUIRED" inspite comments field is filled. I have attached the same in the presentation. Please go through it help in this regard.

Thanks and Regards

M Gopalakrishnan

Hi all,

 I am working on simulation of necking in a uniaxial tension test using sheet specimens of 1 mm sheet thickness. I have given stress strain data upto a plastic strain of 1 , I am using 4 elements in the thickness direction of the sheet.My job is able to complete but with lot of warning messages as follows:

1) The strain increment has exceeded fifty times the strain to cause first yield at 286 points

2) The system matrix has 174 negative eigenvalues.

I am doing analysis in ANSYS which requires the contact pair to be defined. I am unable to select an appropriate value of Pinball region, Penetration Tolerance and normal penalty stiffness. Does any body have an idea how to select the good values for better solution? If you have anykind of material related to contact pair kindly email me at hijazi.19 [at] gmail.com (hijazi[dot]19[at]gmail[dot]com)

 Thanks

Dear Prof.Barber,

     This is the proof of the theorem I mentioned before. This proof is recorded in a book

  (titled as variational principle in elasticity and its applications)  written by Prof.Hai Chang Hu, one of the inventors of the well-known Hu-Washizu generalized variational principle. It is written in Chinese. I translated it into English. Of course, all errors and misunderstandings are due to me. I think this proof is elegant and accessible to most of the students with engineering background.

Hi Every one

Greetings!!!

 I am a new entrant to this site. This site seems to be very good towards technical aspect.

First of all I would like to introduce myself. I am a Ph.D student working in the area of fatigue.

- Is there anyone to support and share the knowledge in the domain of fatigue?

- Can anyone guide towards the websites that provides very good information about fatigue and related literatures.

Thanks and Regards

Gopalakrishnan Mohanam