AUTHORS: Radim Jarkovsky, Stepan Major, Pavel Cyrus

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ABSTRACT: An experimental device was proposed to determine the elastic tensile and compressive modulus Et and EC of materials simultaneously through the deformation and displacement measurement in the split test, which is based on study of disk loaded by a pair of radial opposing forces. The electronics controlling experimental device used Arduino platform. Based on the proposed test theory, there is method based on comparison of Finite element model and data obtained from modified Brazilian test. The modification of Brazilian test is based on use curved jaw. Curved jaws are necessary for fulfillment requirement of sample breaking in the middle. These condition is a necessary condition for determining traverse tensile strength. The exact description of jaws curvature is necessary for calculation of elastic modulus, because the deformation of jaws and stone sample affects results of determination of elastic modulus. The big problem description deformation in the area of contact is probably a caused that the change in shape of a cylinder in contact, is due not only elastic deformation but straight graining and loss of material. Three groups of experimental data are used to validate the proposed test theory. The analysis indicates that the estimated Et and Ec of materials have high reliability when measured vertical displacement of jaws and rock sample i.e changes in diameter of sample simultaneously. The measurement error of displacement results in that the estimated Et and Ec of materials follow the changes in the radius of the cylindrical contact. The validation works indicate that the proposed test method is feasible and liable and is convenient to determinethe Et and Ec of materials simultaneously through the simple indirect tension test. This device was developed as part of Master Thesis.

KEYWORDS: - Experimental device, Elastic modulus, Arduino controller, Tensile loading, Cylindrical specimen, Testing stone

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