The company ARAKO (belongs to the engineering division of the corporation Rosatom – Atomenergomash), a traditional manufacturer of industrial valves from Opava, has been cooperating with secondary schools and universities of technical orientation for a long term. A very interesting cooperation was held with Bc. Miroslav Nevřela, a student of VŠB-Technical University of Ostrava, who underwent a six-month professional practice at the company last year. He conducted modal tests of a forged valve under an expert supervision of doctoral candidates Ing. Jakub Ciencala and Mgr. Ing. Alena Bilošová, Ph.D., in the first quarter of 2017.
Together with personnel of VŠB-Technical University of Ostrava, School of Machinery, Applied Mechanics Department, Miroslav Nevřela conducted modal tests on the gate valve of nominal diameter DN 200 and class Pp 12.9 MPa, which he will use as a basic document for his thesis named „Identification of modal characteristics of a forged gate valve by calculation and by experimentation“.
The goal of the tests was to find (by experimentation/measurement) modal characteristics, natural frequencies, mode shapes and damping ratios of the system measured. The result of the tests was compared to natural frequency calculations conducted using a numerical simulation. This method is used by design calculation engineers of ARAKO in their work. The results of the modal test were in accord with calculations, proving the high level of ARAKO´s design calculation department engineers.
To make the importance of the tests conducted easy to understand:
By conducting modal tests, we can obtain modal parameters of the system and use them for solving problems associated with vibrations. Vibrations mean an important risk and limitation for the design of a wide range of machinery products. They may cause the product integrity to break or the machinery performance to decrease. In addition, excessive vibrations may result in an excessive noise and troubles during operation.