The number of registered users of iMechanica exceeded 10,000 the other day.  The total number of posts is 4379, and the total number of comments 9222.  iMechanica was launched in September 2006, with the following mission:

Colleagues, can I draw your attention to the following position. Closing date is 5th December. If you want to know more about the post or the department feel free to contact me.

Thanks, Charles

Lecturer in Bioengineering

School of Engineering, Durham University, UK

Hi all!

I read that the "cmplementary starin energy of a structure is not equal to sum of the complementary strain energies of it's components, if there is non-linearity like geometric"

That means for e.g. if I consider a truss stucture subjected to loading so that it undergoes geometric non-linearity, then the sum of the complementary strain energies from members is not equal to complementary strain energy of the structure.

 I request somebody to explain why is it so??

 Thanks and regards,

- Ramdas

Checking the iMechanica web, I notice some discussion about the Cauchy stress tensor, whether it is covariant or contravariant.  Well, a tensor is neither covariant nor contravariant, while it can be expressed by its covariant, contravariant, or mixed *components* with respect to any arbitrary coordinate system. See the attached short explanation.

Call for papers (abstract dealine: 28 Feb, 2009): 

"Advances in smart materials and adaptive structures" symposium to be held at the third international conference on integrity, reliability and failure, IRF2009

July 20-24, 2009 Porto, Portugal  

Sponsored by the Department of Mechanical and Industrial Engineering, University of Toronto 

Please submit abstract by email to Aarash Sofla: sofla (at) mie.utoronto.ca

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2、Lemaitre J, Plumtree A. Application of damage concepts to predict creep-fatigue failures. Journal of engineering materials and technology. Transactions of ASME. 1979,101:284-292

3、Wang J. Low cycle fatigue and cycle dependent creep with continuum mechanics. International Journal of damage mechanics. 1992a,1(2):237-244