ІНФОРМАЦІЙНО-ВИМІРЮВАЛЬНА СИСТЕМА ДЛЯ ВИЗНАЧЕННЯ АМПЛІТУДИ РЕЗОНАНСНИХ КОЛИВАНЬ ЗАКРІПЛЕНОГО ПОЛІМЕРНОГО СТРИЖНЯ НА ОСНОВІ ЦИФРОВОЇ ОБРОБКИ ТА АНАЛІЗУ ЗОБРАЖЕННЯ

Abstract

For the experimental determination of the real part of the complex dynamic Young's modulus and the tangent of the mechanical loss angle of the polymeric materials, the method of shear oscillations of the fixed sample is used. The essence of the method is to measure the amplitude of the resonance oscillations of the sample, in the form of a rod when the frequency of the disturbing force changes. Based on the values of the amplitude of the transverse oscillations of the sample at different frequencies, a resonance curve is constructed, the parameters of which are the oscillation frequency and the relative amplitude. The structure of the information-measuring system for determining in real time the amplitude of the resonant oscillations of the rod in the set frequency range is presented. The determination of the amplitude of the oscillations is based on the digital processing and analysis of the image of the sample obtained by the webcam. The information management system hardware and digital image processing algorithm is implemented in the MATLAB software application using the capabilities of the graphical user environment and the NI-VISA package. The proposed sequence of operations of digital image processing which consists of capturing RGB image, converting the image to monochrome, improving the image by changing the brightness of pixels, local averaging with defined pixel window size and impulse response of the filter, border selection on the image and binarization of the image by clipping threshold of brightness. The algorithm for determining the amplitude of oscillations is based on the determination of the right and left boundaries and the linear size of the area of the binary image with pixel values equal to one relative to the vertical baseline. In addition to determining the left and right boundaries, the algorithm provides for the adjustment of the vertical baseline to the image of the sample oscillations. Based on the obtained results the possibility of constructing a resonance curve of the relative amplitudes of oscillations of the sample from the frequency of its excitation is shown.