Stand for dynamic tests of methods vibration diagnostics of compressor blades

В статье рассматривается стендовая реализация предложенного авторами способа проведения экспериментов с рабочими лопатками аксиальных компрессоров, целью которых является отработка методов мониторинга вибраций лопаток и алгоритмов выявления характерных дефектов (усталостных трещин) непосредственно во время работы компрессора. Для обеспечения безопасности экспериментов с повреждёнными компрессорными лопатками в конструкции стенда применён один из эвристических принципов решения изобретательских задач, сформулированный Г.С. Альтшуллером, который состоит в том, что движущиеся на натурном объекте детали (лопатки) делают неподвижными, а неподвижные детали (датчики) приводят в движение таким образом, чтобы сохранить скорости их относительных перемещений. Рассмотрена конструкция стенда и состав измерительных приборов. Приведены результатов экспериментов с исправными компрессорными лопатками и с лопатками, имеющими различные стадии развития дефектов (усталостных трещин). Показано, что графическое представление ранжированных массивов измеренных временных интервалов позволяет судить о наличии дефекта и о стадии его развития. The article discusses the bench implementation of the method proposed by the authors for conducting experiments with rotor blades of axial compressors, the purpose of which is to develop methods for monitoring blade vibrations and algorithms for detecting characteristic defects (fatigue cracks) directly during compressor operation. To ensure the safety of experiments with damaged compressor blades, one of the heuristic principles for solving inventive problems, formulated by G.S. Altshuller, which consists in the fact that parts (blades) moving on a full-scale object are made stationary, and stationary parts (sensors) are set in motion in such a way as to maintain the speed of their relative movements. The design of the stand and the composition of the measuring instruments are considered. The results of experiments with serviceable compressor blades and blades with different stages of development of defects (fatigue cracks) are presented. It is shown that the graphical presentation of ranked arrays of measured time intervals allows one to judge the presence of a defect and the stage of its development.

Sensitivity of a vibroacoustic signal to a change in the state of the surface layer of ceramics during frictio

The high information content of the vibroacoustic signal in the frequency range of 10‒16 kHz to the change in the state of the surface layer of the ceramic sample during frictional interaction with the steel disk was established. The results obtained indicate the possibility of using vibration diagnostics systems for monitoring the state of ceramic parts during operation and fi tests.

VIBRATION PROCESSES AND THEIR RELATIONSHIP WITH DEFECTS

ABSTRACT The article is devoted to vibration diagnostics, an effective method for assessing the parameters of the mechanical state of centrifugal pumping units. The use of vibration diagnostics allows, due to early detection of malfunctions, to improve target operation, increase the turnaround time and reduce the likelihood of emergency destruction of pumping unit elements. Diagnostic signs of the presence of defects in various elements of the pumping unit are presented. During the development of diagnostic methods, the character stages of the development of injuries are selected. These stages are the formation of the injury, the accumulation of injuries, collapse, and so on. consists of stages. Dynamic forces are considered to be the main cause of vibration in machine parts. It is under the influence of dynamic forces that fatigue breaks down in machine parts. The use of vibrodiagnostics in machine parts allows to accurately assess the degree of damage to its individual nodes. This, in turn, leads to improved operating conditions. In conclusion, it should be noted that vibrodiagnostics not only detects malfunctions in machines, but also reveals the causes of its formation. Keywords: vibrodiagnostics, improvement of operational conditions, determination of defects, probability of emergency destruction, repair, assessment.

Determination of the variable density of the rod from natural frequencies of longitudinal vibrations

Rods of various configurations are elements of many structures and machines. Therefore, the acoustic and vibration diagnostics of such parts has been widely developed. The paper considers the problem of determining the variable density of the rod from the natural frequencies of longitudinal vibrations. It is assumed that the density changes along the axis and is described by a polynomial function. This approach allows one to determine the law of density variation from a finite set of eigenvalues. The results of the study can find applications for finding hidden defects in steel and composite rods, which arise during the production process or due to corrosion.

Application of spectral analysis methods for data pre-processing of anomaly detection problem of vibration diagnostics in non-destructive testing

The paper is devoted to the problem of primary data processing obtained in the vibration measurements during the processing of the workpiece on a milling machine with computer numerical control. An experimental setup is described and an algorithm for analysing vibration diagnostics signals using a mathematical machine learning tool is proposed. Special attention is paid to the study of the rigidity characteristics of the machine at different relative positions of its components. The analysis of the equipment design and factors affecting the ongoing process is carried out, as a result of which the received signal is processed and its characteristic fragments in the time and frequency domains are identified. The data is prepared for further use in solving the problem of detecting anomalies of the technological process, which implies predicting the progress of the technological process based on a mathematical model constructed using machine learning methods, and identifying deviations of the real technological process from the forecast. Preliminary preparation is carried out using the windowed Fourier transform. Various variants of windows in the transformation are considered, including those constructed using atomic functions. Calculations are performed using the Python 3.9 language, the main results are supported by graphs. The development of training methods for the considered models of neural networks is the subject of further research.

INFLUENCE OF VIBRATION MAGNITUDE IN MACHINING OF MATERIALS BY TURNING TECHNOLOGY

The basic task of any prosperous company is to minimize operating costs to a minimum. High-quality maintenance ensures an increase in the operational reliability of the machines. It is important to find a compromise between scheduled maintenance and production process requirements, so resources are spent to optimize the maintenance schedule. This is provided by technical diagnostics, which helps to monitor the technical condition and functional properties of the monitored machine under specified operating conditions. The publication is focused specifically on vibration diagnostics and its use in monitoring the transmission of vibrations during the turning of selected types of materials in the company with a focus on engineering, the ZVL AUTO s.r.o. The scope of research is mainly focused on the monitoring process in order to analyze the magnitude of vibration acceleration at two preselected parts of the machine tool - lathe.