Abstract - Indentation experiments on very thin films are analyzed by employing a rigorous solution to model elastic substrate effects. Two cases are discussed: elastic indentations where film and substrate are anisotropic, and elasto-plastic indentations where significant material pile-up occurs. We demonstrate that the elastic modulus of a thin film can be accurately measured in both cases, even if there is significant elastic mismatch between film and substrate. 

This manuscript has been accepted for publication in Journal of Materials Research.  

Dear iMechanicas,

I just started doing nanoindentation tests on dry biological samples (wood) with a flat punch tip and I have problems analyzing the results! I would be happy if anybody could give me some suggestions.

While running a test I receive quiet good force-displacement curves (no adhesion, good surface find, no time-depend behavior) but the values for the recieved elastic modulus are not stable! The value scatters over the whole range of displacement.

And sometimes the curve for the Phase angle is not like usual. Sometimes it just shows a wild zick-zack pattern.

Unfortunaltely I have no one to ask at my institute :(

Dear Colleague:

Oral abstract submission is now closed for the Workshop on Probing the Limits of Strength; however, the deadlines for poster abstract submission (200 words or less to berkeleyworkshop09@gmail.com) and advance registration have been extended to the end of July. See the Workshop's website for further details: http://www.mse.berkeley.edu/groups/aminor/09_Workshop/Workshop_Announcement.html. The Workshop's program and the registration form can be downloaded from that website.

4 year Postgraduate Fellowship in the School of Physics and the CRANN Nanoscience Institute,Trinity College, Dublin, Ireland

Nanomechanics Group of Dr. Graham Cross (webpage)

Dear Colleague:
 
You are cordially invited to attend a special Workshop on Probing the Limits of Strength, which will be held at Lawrence Berkeley National Laboratory on August 10-12, 2009. This workshop aims to bring together researchers with an interest in experimental and theoretical studies of the fundamental limits of strength in materials. The workshop will include a strong lineup of national and international speakers on advanced mechanical testing techniques and computational materials science of materials deformation at the elastic limit.

PostDoc Position Available

Ortiz Laboratory at MIT

Professor Christine Ortiz, Department of Materials Science and Engineering , Massachusetts Institute of Technology, Cambridge, MA, USA

I am trying to simualet Indentation Hardness Testing in ABAQUS and feeling like that there is some problem in my model.

Whenever I try to plot load-displacement curves it gives me bumps in the curve. Any idea, what should I do?

Should I reduce mesh size, I have done but then it gives me error with step size and so on.,

Abstract – A data analysis procedure has been developed to estimate the contact area in an elasto-plastic indentation of a thin film bonded to a substrate. The procedure can be used to derive the elastic modulus and hardness of the film from the indentation load, displacement, and contact stiffness data at indentation depths that are a significant fraction of the film thickness. The analysis is based on Yu’s elastic solution for the contact of a rigid conical punch on a layered half-space and uses an approach similar to the Oliver-Pharr method for bulk materials. The methodology is demonstrated for both compliant films on stiff substrates and the reverse combination and shows improved accuracy over previous methods. 

We are pleased to inform you that Ebatco’s Nano Analysis and Testing Laboratory (NAT Lab) now is open to serve your nanoscale mechanical and tribological testing and analysis needs. The NAT Lab’s staff scientists have more than 10 years of nanomechanical and nanotribological testing, applications R&D and instrument development experience. The lab is equipped with state-of-the-art nanoindenters with nm-resolution in-situ SPM imaging capability and full lines of advanced options such as nanoDMA, modulus mapping, feedback control, heating/cooling stage, vacuum chuck, and environmental control and isolation chamber.

Abstract:

As the thickness of coating thin
film is reduced it becomes increasingly difficult to measure their adhesion,
hardness, toughness by conventional methods. Indentation test methods are well
established for the determination of elastic modulus and hardness, but methods
for assessment of fracture properties are much less developed. In this term
paper, existing metrology of using indention to study fracture toughness will
be summarized and mechanics of fracture under indentation will be studied.
Experimental plans of investigation fracture toughness of OSG low-K film will
also be evaluated in the end.

Can we map the eastic modulus of a and c domians? Can we mechanically switch the domains and let them function as nanoactuators and sensors?

B. Li, M. K. Kang, K. Lu, R. Huang, P. S. Ho, R. A. Allen, and M. W. Cresswell, Nano Letters 8, 92 -98 (2008). (Web Release Date: 07-Dec-2007; DOI: 10.1021/nl072144i)