Micromechanics---loosely speaking, is the study of heterogeneities in materials and its consequences for material or continuum behavior. This encompasses studies of inclusions, dislocations, cracks or more generally defects. A related problem is that of "coarse-graining" or in other words the effective homogenized properties of a heterogeneous material. The latter is a recurring theme in all of physical sciences not just solid mechanics. Micromechanics, a formidable subject by all means, dominated a substantial part of the history of solid mechanics. Several of our Timoshenko awardees have been associated with this subject, e.g. Eshelby, Hill, Keller, Irwin, Rice among others.

A postdoctoral research position is available immediately at the Mechanobiology Group, Nuffield Department of Orthopaedics, Rheumatologyand Musculoskeletal Sciences at the University of Oxford to study tendon mechanobiology and repair following injury or pathology. This is an exciting opportunity to join a multi-disciplinary team drawn from the Botnar Research Centre, the Oxford Institute of Biomedical Engineering and the John Radcliffe Hospital to work at the forefront of strategically important musculoskeletal research.

There are several exact relations from the theory of composites that can be used to determine whether a new numerical or analytical approach gives reasonable answers. Here's a paper on some exact relations that I wrote up a long time ago and just recently posted on Scribd. 

Dear friends / distinguished imechanicians,

I am trying to use micromechanics in  foams to numerically compute the elastic constants using one unit cell. I see some literature available when simple unit cell shapes are assumed (like cubical or hexagonal). However there is nothing specific about modelling for tetrakaidecahedral foams. Assuming the right boundary conditions would be critical for computing the constants. I am not able to come up with a reapeating pattern for determining the places to apply the boundary conditions.

Have any of you done something similar to this and if yes, would you want to throw some light on the same.

 Thanking you

Prasanna 

The Computational Solid Mechanics group under the direction of Prof. Marisol Koslowski in the School of Mechanical Engineering at Purdue has an opening for a postdoctoral position in the area of multiscale modeling as part of the project “Plasticity in ultrafine grained materials” funded by DOE. A successful candidate is expected to have a strong background in computational solid mechanics and programming experience. While experience in plasticity using dislocation dynamics or phase field methods is a plus, all outstanding candidates will be considered.

The Materials Research Department at Risø National Laboratory for Sustainable Energy, Technical University of Denmark, is seeking a PhD student within the field of advanced fibre composites. The PhD position will aim at increasing the fundamental knowledge of wood fibres and their behaviour as reinforcements in composite materials studying e.g. wood fibre structure and mechanical and hygroscopic properties e.g. by micromechanical modelling and advanced testing.

For more details see: http://www.dtu.dk/English/About_DTU/vacancies.aspx?guid=22340178

Helix is a very interesting structure. There are many biopolymers that have a helical structure. 

• How can someone model the helix in mechanics?
• How can the helix reinforce a rod? 
• How does this structure reflect the mechanical properties of biopolymers?

We find a way of constructing special inclusions by solving variational inequalities. As a side result, the Eshelby conjectures, which asserts that uniform eigenstress induces uniform elastic strain if and only if the inclusion is an ellipsoid, are solved. In a periodic setting, we can construct optimal ordered structures in the sense of attaining the Hashin-Shtrikman bounds. These works have been submitted and preprints are available at http://www.its.caltech.edu/~liulp/. Examples of multiply-connected inclusion with Eshelby uniformity property are shown below, see the papers for more examples and description of numerical schemes.

Adelaide, Australia, August 24 - 29, 2008

Final Announcement and Call for Papers

http://ictam2008.adelaide.edu.au

Hi everybody, 

In fact, I encounter this problem in my research and I would be grateful if someone can help. In micro mechanics, there are many problems concerning Green functions, e.g: the displacement is calculated from the distributed force in the domain, etc. Consider the following integral to determine the displacement field.

u(x)=∫A(x,y)dVy where A(x,y) is singular of order r-2 (i.e r2=(x-y)(x-y)).

You are cordially invited to submit an abstract to the symposium on “Emerging Methods To Understand Mechanical Behavior” at 2008 TMS annual meeting, New Orleans, LA, March 9-13, 2008.  

Concrete is currently the most important material in the building industry. However, it is very weak in tension,  compared to its strength in compression. To overcome this problem, prestressed concrete is usually used.  Prestressed concrete is plain concrete with reinforcement of steel, polymers or, in this case, shape memory alloys. The prestressing is usually introduced by applying tension to the reinforcement in the concrete members. Consequently, initial compressive stresses are transmitted to the concrete matrix; the application of permanent  compressive stress increases the apparent tensile strength of the concrete, since upon tensile loading, the compressive stresses must first be nullified.

Computational Mesomechanics of Composites, by Leon Mishnaevsky Jr. (Risoe National Laboratory, Technical University of Denmark)

This message about a new book came over the PoroNet (poroelasticity network) mailing list:

Dear Colleagues:

      I would like to inform you that my book "Micromechanics of Heterogeneous Materials” (containing around 700 pages, 140 figures, 3000 formulae, and 1200 references) should be published by Springer on 07.06.07. [Details are on the web http://www.springer.com/west/home/engineering?SGWID=4-175-22-173670290-detailsPage=ppmmedia|toc ] .

      In the framework of a unique scheme of the proposed multiparticle effective field method, we have undertaken in this book an attempt to analyze the wide class of statical and dynamical, local and nonlocal, linear and nonlinear multiscale problems of composite materials with deterministic (periodic and nonperiodic), random (statistically homogeneous and inhomogeneous, so-called graded) and mixed (periodic structures with random imperfections) structures in bounded and unbounded domains, containing coated or uncoated inclusions of any shape and orientation and subjected to coupled or uncoupled, homogeneous or inhomogeneous external fields of different physical natures.

        Any the remarks and comments regarding the book will be fully appreciated.

The 28th Risø International Symposium on Materials Science addresses the whole range from fundamental understanding to industrial applications. Topics include:

• surface functionalising
• chemical and physical surface characterisation
• mechanical characterisation of interfaces
• micromechanical modelling
• fibre/matrix debonding
• sizings effects on composite processing
• interface aspects and their integration into manufacturing
• fibre bridging in composites
• fracture resistance of composite
• tensile and compressive strength of composite
• macroscale modelling
• hole and notch sensitivity

More information, including invited key-note speakers, see web site here.