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stable elements for mixed elasticity

Submitted by Alessio on
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fem elasticity

I'm very interested in the choice of the finite element spaces for elasticity. I want to choose elements for the stress and the velocity, I was suggested to use piecewise constant for the stress and piecewise linear for the velocities to satisfy the Babuska-Brezzi condition. Is that right? I've heard that I can't use only 6 components for the stress in this way, but I must add some additional constraint to enforce its simmetry. I'm looking for additional documentation, but I can't find any. Has someone got any suggestion? Thanks.

cracking analyses in a bended sandwich beam

Submitted by Ilias I. Tourl… on
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fracture
J integral
Energy release rate

I'm studying cracking analyses in a three point loaded specimen of a composed beam.I'm using ANSYS and i want to create codes for estimation of J integral and energy release rate in the vicinity of crack tip.After that i'll calculate the stresses and strains fields,and then i can compare the equivalent fields i retrived using CTOD  and K(I,II,III) factors (according to ANSYS algorithm).

My problem is that I'd like to find a relationship between the above mentioned quantities(J,G)  with K(I,II,III)factors.

News feeds from the IMechE

Submitted by Martin Pratt on
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RSS
engineering-events
feeds
imeche

I run part of the website here at the IMechE in the UK. Since we have many international visitors to our technical events I thought I'd point out that we've finally brought out a whole raft of RSS goodness with the launch of a range of industry specific feeds from our calender of events. We intend to launch more feeds for other content areas soon.

Relationship between Hardness and Elastic modulus?

Submitted by Anonymous (not verified) on
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hardness

What is the relationship between hardness and elastic modulus? The higher hardness, the higher elastic modulus?  My understanding is that hardness is a local mechanical property, and 
elastic modulus is an averaged global mechanical property.  Am I right about this? 

Pre-stress & Initial stress

Submitted by Amin on
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Hi AllI am working on Simulation of nonlinear phenomena in MEMS devices. I do not know for residual stress in Microcantilever beam I should use pre stress or initial stress. I checked initial stress by Shell 181 and solid 186, but answers are for from experiments (around 100 times). I do not know what the difference between initial stress and pre stress is.

 

 

Free Online Access to latest Mathematics and Mechanics research until November 30, 2007

Submitted by ndmccrae on
research

As a courtesy to mechanical professionals and academics at large, I would like to inform you about the current free access period to mechanical research including the following journals:

Journal of Damage Mechanics

Mathematics and Mechanics of Solids

From now until November 30, 2007, you can access any materials science, mechanics or engineering journals online (from volume 1, issue 1 to current) free of charge!

Changing element status in ANSYS

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failure analysis

Respected sirs/madams

I am working on failure analysis of concrete. I am trying to simulate in ANSYS, I heard about element birth/death option for changing the status of element during analysis. My doubt is whether I can use this element birth/death option for analysis or this is only used as a postprocessing tool.

 I am trying is to reduce the stiffness of the elements whose maximum principal stress reaches the ultimate strength of concrete and than further apply load in the susequent load step on the finite element model whose elements are removed.

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