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Multiaxial behavior of nanoporous single crystal copper: a molecular dynamics study

Submitted by Kejie Zhao on
research
molecular dynamics
size effect
incipient yield surface

The stress-strain behavior and incipient yield surface of nanoporous single crystal copper are studied by the molecular dynamics (MD) method. The problem is modeled by a periodic unit cell subject to multi-axial loading. The loading induced defect evolution is explored. The incipient yield surfaces are found to be tension-compression asymmetric. For given void volume fraction, apparent size effects in the yield surface are predicted: the smaller behaves stronger.

A quesntion of Negative Eigenvalues in Buckling analysis

Submitted by Gang Liu on
research

A simple model was constructed to convince the analytical solution and a numerical results.

For instance, the instability of an Euler column was investigated under uniform pressure with magnitude equal to 1 on the top surface. The FEM calculation (Abaqus) exhibits that the eigenvalue for mode 1 is negative and the minus value cann't  be transformed to positive though I have try to variate the mesh size and category as well as  calculative measures with Lanczos or subspace.

BTW: the step for this model is applied with Buckle in Linear perturbation

"Crack" versus "Fracture"

Submitted by Andrew Bunger on
research
fracture mechanics
crack

 It seems that within the field of fracture mechanics, some authors use "fracture" to refer to the mechanism of creating new surfaces within a body by breaking the material bonds and reserve the word "crack" for the sharp-tipped discontinuity that results from fracture of a brittle material. But it does not appear that this distinction is followed consistently throughout the literature, and perhaps different research areas within the fracture mechanics field use the two words in different ways.

Questions on ferroelectrics: why tetragonal ferroelectric ceramics are difficult to pole while rhombohedral ceramics easy to?

Submitted by Faxin Li on
research

 

It may be well known to researchers on ferroelectrics that tetragonal ferroelectric ceramics, such as BaTiO3, Ti-rich lead titanate zirconate (PZT), are difficult to pole even using a high DC field with long holding time. While the rhombohedral PZT or PZT near the morphotropic phase boundary (MPB) are easy to pole, especially the latter. Why?

 

Types of Impurities in single crystal semiconductor nanostructures

Submitted by ashfaqadnan on
research

Hi,

I am looking for information about formation, distribution,
concentration and stability of impurties/ defect in semiconductors,
specifically for cubic SiC. I have some discrete set of
literartures which are neirther systematic, nor elaborate. I would truly
appricitate if any one can suggest me some references.

 

Sincerely,

-Ashfaq Adnan 

Call for IUTAM Symposia & Summer School Proposals

Submitted by Carl T. Herakovich on
research
symposia
summer schools

ADVANCED CALL FOR PROPOSALS: IUTAM SYMPOSIUM and INSTRUCTIONAL SUMMER SCHOOLS for 2010 and 2011 (Proposals due no later than January 15, 2008)

The United States National Committee on Theoretical and Applied Mechanics (USNC/TAM) seeks proposals from U.S. authors and institutions to host IUTAM (International Union of Theoretical and Applied Mechanics) Symposia or IUTAM Instructional Summer Schools in 2010 or 2011.

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