Two days ago, Giulio Fanti presented a paper, A New Cyclic-Loads Machine for the Measurement of Micro-Mechanical Properties of Single Flax Fibers Coming from the Turin Shroud at The Italian Association of Theoretical and Applied Mechanics (AIMETA) Congress in Turin, September 17-20, 2013. The paper was co-authored by Pierandrea Malfi. Both are from the University of Padua. Giulio was kind enough to provide a copy of the paper for the readers of this blog ahead of the publication in the conference’s proceedings. Please respect the copyright and the kindness. Comments are, of course, welcome.
As a bibliographic research has shown the absence of machines of the type requested, it has been necessary to design, build and test a new cycling-loads machine capable to measure the micro-mechanical characteristics of flax fibers like Young modulus, tensile strength and the loss factor. The flax fibers in question have diameters of 5-25 μm and lengths of 1-3 mm.
The requirements for the testing machine are to furnish the stress-strain parameters, with an uncertainty not greater than 10%, relative to different loading-unloading cycles measuring fibers from 1 mm to 30 mm long, with 1% strain, a resolution of the order of 0.1 μm and capable to measure forces up to 0.5 N with a resolution better than 2 μN.
The design problems have been solved by employing a mechanical lever displaced by a micrometric screw to impose the displacements and by using an analytical balance, properly calibrated to measure the corresponding forces. The single flax fibers have been glued on particular polyester bases build up for the purpose.
The machine has been used to date fibers coming from the Turin Shroud. To reach this purpose, proper calibration curves have been determined using a series of ancient flax textiles. The Turin Shroud fibers resulted of 400 AD with an uncertainty of ±400 years at 95% confidence level, thus compatible with the epoch in which Jesus Christ lived in Palestine.
Link to paper in this blogs archives:
My reading of the posting only, suggests there must be typos in the various dimensional abbreviations. Flax fibres with diameters in the range 5m to 20m make no sense, even if mm is meant instead of m. I don’t know what to make of the statement “to measure forces up to 0.5 N with a resolution better than 2 N.” Are in fact micro-meters meant, and the Greek ‘mu’ hasn’t transliterated? The release refers to “cyclic loading”; This looks like Prof Fanti is attempting to discover the fibres’ present fatigue characteristics, in the possible hope of making inferences about the age from the number of cycles the cloth may have experienced over the ages. I’m drawing on my early Engineering lab time in “Strength of Materials” classes here.
Dave, I took the abstract directly out of the back of the paper (copy and paste), which clearly is wrong. That should be μm (Mu) not m. However the main body of the paper seems to be right so I have replaced the abstract in this posting with the initial summary from the opening paragraphs of the paper. You can refer to the pdf to see the abstract as it was. Thanks for bring this to my attention.
Thanks, Dan. I haven’t got around to reading a decent Engineering paper for very many years now (developed too many other interests), so I’ll look forward to working my way through this one.
I’d like to see some thorough evidence of the robustness of this approach by seeing it applied to a number of flax fiber objects whose date is known, so that the method’s credibility can be rigorously tested
You hit the nail on the head.
Wouldn’t the heat from the various fires the Shroud has been exposed to affect the strength of the fibres? If so, the result would be younger than 400AD.
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