Experimental and calculation determination the form of proper oscillations of the polymer cylinder

Abstract

In modern mechanical engineering, products made of non-metallic materials are widely used. Their low cost and wide range of properties have led to a wide variety of uses for such materials in the creation of various parts. Among the geometric shapes of parts, various configurations, including the classic cylindrical one, are available. These can be various types of bushings, pistons, and pipes. Products made of non-metallic materials often operate under high dynamic loads and are subjected to various types of vibrations, making it relevant to determine the dynamic loading parameters. Such parameters primarily include the forms of natural oscillations and their corresponding frequencies. The object of the study is a polymer product in the form of a truncated cone with a diameter of 70.5 mm from the bottom and 69.0 mm from the top, height of 80 mm, and wall thickness of 2.2 mm. The purpose of this study is to determine the smooth frequencies and forms of oscillations of the aforementioned product. The goal is achieved using a modern experimental method of real-time speckle interferometry, which belongs to the optical methods of non-destructive testing and is protected by many patents of Ukraine. The optical scheme of the experimental stand is described in this publication, along with the equipment characteristics and software features. A feature of this study is the use of non-contact excitation when the vibration-generating element is near but does not touch the object under study. In this case, the amplitude is transmitted through a layer of air, and the vibration exciter does not change the mass of the object under study. Consequently, there is no distortion of the forms and a change in the frequencies of smooth vibrations. In the range of 0…5 kHz, ten forms of natural oscillations were experimentally discovered, which are given in this work. Simultaneously, the number of nodal lines passing perpendicular to the axis of rotation of the object n in the studied range changes from 0 to 2, and the number of nodal line pairs passing in the meridional direction m changes from 2 to 5. Refinement of the number of forms and improvement of the quality of identification were performed in the Solidworks software package, which allowed the detection of 12 forms of oscillations in the specified range, which is explained by the insufficient strength of remote excitation for the two undetected forms. Despite this, the root-mean-square deviation between the calculated and experimental studies is 4.2%, which is acceptable for further calculations.