V.G. Zhukov1, N.R. Andreev2, D.N. Lukin2
1Moscow State University of Food Productions, Volokolamskoe shosse, 11a, Moskva, 125080, Russian Federation
2All-Russian Research Institute of Starch Products ul. Nekrasova, 11, pos. Kraskovo, Moskovskaya obl., 140051, Russian Federation
Abstract. In the article it is presented the mechanism of strain and strength properties of the cell structure of potato tubers, studied by the compression of cylindrical samples cut out from them. The research feature consisted in carrying out the intermediate unloading of samples right up to the zero compression strain that was followed by repeated loadings. The intermediate unloading was carried out after exceeding of compression strain of 0.1 MPa. This strain value means the end of the initial stage of the compression strain chart appearing a curve with its bulge directed to an axis of deformations. The number of intermediate unloading of samples with different strain value in them amounted from one to three. While increasing the number of unloading the compression chart gets the apparent flat site in the field of strain close to the strength limit. At the same time, it is noted the decrease in the intensity of relaxation effects in the form of a compression strain drop during 30-second breaks of loading. The mechanism of sample deformation at compression strain sigma from 0 to 0.1 MPa happens as elastic cell deformation which is not uniform in cell structure; after exceeding of this strain limit it goes as gradual destruction of the most loaded cells according to their quantity, merging of these destructions and the final sample destruction as fragile material. Thus, the sample cell structure proves to be partly as plastic material collapsing with large residual deformation (close to 0.3), partly as the fragile material with destruction at the angle 45 degrees to a longitudinal axis of the sample, i.e. it is of a hybrid strain-strength type. Therefore, the deformation after the intermediate unloading should be conditionally considered as conditionally plastic, quasiplastic. It is designated as epsilon*.
Keywords: potato tuber, cylindrical sample, compression tests, chart of compression, strain, straining properties, intermediate unloading, destruction mechanism, fragile destruction.
Author Details: V.G. Zhukov, D. Sc. (Tech.), prof. (e-mail: Этот адрес электронной почты защищён от спам-ботов. У вас должен быть включен JavaScript для просмотра.); N.R. Andreyev, D. Sc. (Tech.), corresponding member of the RAS, scientific supervisor of institute (е-mail: Этот адрес электронной почты защищён от спам-ботов. У вас должен быть включен JavaScript для просмотра.); D.N. Lukin, Cand. Sc. (Econ.).
For citation: Zhukov V.G., Andreyev N.R., D.N. Lukin. Deformation Mechanism by Compression of Cylindrical Samples from Potato Tubers. Dostizheniya nauki i tekhniki APK. 2017. Vol. 31. No. 6. Pp. 80-83 (in Russ.).