Evaluation of elastic properties for tissue of agricultural products by means ofdigital imaging assisted method-Measurement of Poissonu27s ratio for a tissue of boiled Japanese Radish and Carrot-

摘要

Youngu27s modulus and Poissonu27s ratio, which characterized elastic properties of a material, were measured bymeans of compress utensil and digital images captured by digital camera, and the elastic values were evaluated. Atissue of boiled Japanese radish and carrot root, which is too fragile to measure their Poissonu27s ratio by traditionalmethods, was used as sample materials. Cylindrical samples were cut out of the tissue using a precise apparatusand their dimensions were set to 15mm height and 30mm diameter. The samples were then compressed. The stressof the samples against compression was measured using a creep meter. The compressed deformation of the sampleswas captured by a digital camera and accurately analyzed by high resolution digital images. The Poissonu27s ratio wascalculated from differences in the sample deformation in digital images. A Youngu27s modulus was also calculatedfrom the compressed deformation and the stress. As a result, the Poissonu27s ratio of boiled Japanese radish wasfound to be constant or slightly decrease with boiling elapsed time. The Poissonu27s ratio of carrot also decreasedwith boiling, and its value was smaller than the Japanese radishu27s. On the other hand, the Youngu27s modulus for eachsample decreased sharply when boiling started but after 4 minutes boiling it was stabilized at low values.