Acta Acta Acta Acta Mechatronica Mechatronica Mechatronica Mechatronica - International Scientific Journal about International Scientific Journal about International Scientific Journal about International Scientific Journal about Mechatronics Mechatronics Mechatronics Mechatronics Volume: 5 2020 Issue: 1 Pages: 13-17 ISSN 2453-7306 DETERMINATION OF POISSON NUMBER AT THIN ROD-SAMPLES WITH NON-STANDARD CROSS- SECTIONS BY PENDULUM METHODS Karol Kvetan; Ondrej Bošák; Marián Kubliha; Janette Kotianová ~ 13 ~ Copyright © Acta Mechatronica, www.actamechatronica.eu doi:10.22306/am.v5i1.59 Received: 11 Feb. 2020 Accepted: 02 Mar. 2020 DETERMINATION OF POISSON NUMBER AT THIN ROD-SAMPLES WITH NON-STANDARD CROSS-SECTIONS BY PENDULUM METHODS Karol Kvetan Slovak University of Technology, Faculty of Materials Science and Technology, Institute of Materials Science, Bottova 25, 917 24 Trnava, Slovak Republic, EU, karol.kvetan@stuba.sk (corresponding author) Ondrej Bošák Slovak University of Technology, Faculty of Materials Science and Technology, Institute of Materials Science, Bottova 25, 917 24 Trnava, Slovak Republic, EU, ondrej.bosak@stuba.sk Marián Kubliha Slovak University of Technology, Faculty of Materials Science and Technology, Institute of Materials Science, Bottova 25, 917 24 Trnava, Slovak Republic, Automation and Mechatronics, Bottova 25, 917 24 Trnava, Slovak Republic, EU, marian.kubliha@stuba.sk Janette Kotianová Slovak University of Technology, Faculty of Materials Science and Technology, Institute of Applied Informatics, Bottova 25, 917 24 Trnava, Slovak Republic, EU, janette.kotianova@stuba.sk Keywords: Tensile modules, Poisson number, vibration methods, thin samples, non-standard cross-sections Abstract: The paper describes the measurements of modulus of elasticity of thin samples and related Poisson number by one device – Searle´s pendulum. We have focused our attention mainly to non-traditional samples with non-standard (i.e. other than circular) cross-sections. 1 Introduction, what is Poisson number? The Poisson number μ belongs to basic physical constants characterising the elastic properties of solids. It is defined as the ratio of the relative transverse shortening and the relative longitudinal prolongation. This can be expressed by means of elastic modules as , (1) where E means the tensile modulus (or Young´s modulus) and G is the shear modulus. In our task we have used a device that is able to measure both of these relevant quantities. This device is so-called “Searle´s pendulum”, designed by American physicist G.F.C. Searle [1]. This device is commonly used to measure Young's modulus of thin specimens with classical circular cross-sections. We have extended this use to the measurement of samples with other cross-sections (some of them with a hollow character), and we used the vertical arrangement of the system to measure the shear modulus of elasticity G, too. It also presents a convenient way to determine the Poisson number μ. 2 Theoretical analysis and experimental procedures Searle´s pendulum - in its classic form - is based on two flywheels connected by the sample being measured to create an oscillating system after deflection. The device can be used in two configurations: horizontal and vertical (Fig. 1a) and 1b)). Figure 1 a) Horizontal flywheel set. 1 – hanging threads, 2 – cylinder flywheels, 3– measured wire (arrows indicate the direction of the oscillations, α is an angle of deflection )