D.Rittel's blog

The additive manufacturing technology, among its many advantages, allows us to manufacture solids with controlled enclosed porosity. To the best of my knowledge, this was not doable with conventional machining technologies, but now this is done. In the attached document, the interested reader will find experimental results (both static and dynamic) describing the influence of the porosity on the specimen's performance. We show that while the volume fraction is indeed an important parameter, aas expected, the spatial arrangement of the voids is also of prime importance.

In this movie taken at 1 Mfps using our new Kirana camera (courtesy Y. Rotbaum), one can see a dynamic tension test of a grroved specimen in a tensile Hopkinson bar. The groove is relatively sharp and 10% of the diameter in depth.

It so happens that the dynamic neck inception occurs outside the notch area, in other words a strong geometrical flaw does not dictate the failure locus. We have performed over a hundred of such experiments. This is a very interesting and challenging observation.... 

I believe many of us went through that kind of ostracism. Now, I will provide a concrete argument. This is the reply we received when we responded our paper was indeed of interest to the Physics community, which was first raised as an issue by the editor. We provided a very detailed explanation.

So when they run out of valuable arguments, all they can produce is this pathetic statement below.

The question is more fundamental. Why do we, as mechanicians always welcome papers from physicists, while the reciprocal is far from being obvious?

Here are some movies of impact fracture of various test cases, recorded at up to 5Mfps using the new Kirana camera. The sensor is not the final one yet, but the results are promising. Wedge loaded PMMA plates with holes reveal very nice crack branching (somewhat analogous to fireworks). My students Y. Rotbaum and A. Godinger who performed to test cases thought that Haendel "lascia chio pianga" is appropriate. I don't take a stance on that!

Enjoy:

My new website (still under construction):

rittel.net.technion.ac.il

All welcome :=) 

This basic question is discussed in a paper with S. Osovski and A. Venkert, to appear in Mechanics of Materials.

http://dx.doi.org/10.1016/j.mechmat.2012.09.008 

 We definitely enjoyed working on this aspect of the dynamic shear localization failure process (aka adiabatic shear) and I hope you will enjoy reading it! Comments are welcome :=)