A new cyclic-loads machine for the measurement of mechanical parameters of single flax fibers coming from the Turin Shroud for dating purposes.

The absence in literature of machines suited for the present purposes, suggested the authors to build a new cyclic-loads machine capable to measure the micro-mechanical characteristics of flax fibers like Young modulus, tensile strength and the loss factor. The fibers in question have diameters of 5-25 m and lengths of 1-3 mm. A first prototype has been recently tested with success, but the improved machine here presented overtakes some limits related with the manual data acquisition. 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 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 N. The results have been used to date fibers coming from the Turin Shroud. They 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.