Research on the Formation Mechanism of Surface Morphology in Three-Excitation Ultrasonic Spatial Vibration-Assisted Turning

To improve the machining performance of different processing materials, a three-excitation ultrasonic spatial vibration-assisted turning system is proposed, which realizes the non-unity of the plane where the cutting trajectory of the tool is located. The influence and formation law of three-excitation ultrasonic spatial vibration-assisted turning on the surface roughness of the workpiece under different vibration parameters (amplitude) and machining parameters (cutting speed, cutting depth, and feed) were analyzed by response surface methodology. The results show that in terms of vibration parameters, the influence of ultrasonic vibration applied in the horizontal direction on surface roughness is significantly greater than that of ultrasonic vibration applied in the vertical direction, while the feed has the greatest influence on surface roughness, followed by cutting speed. The surface roughness of common turning, one-dimensional ultrasonic vibration-assisted turning, ultrasonic elliptical vibration-assisted turning, and three-excitation ultrasonic spatial vibration-assisted turning were theoretically analyzed and experimentally compared. The results show that compared with the other three turning methods, the three-excitation ultrasonic spatial vibration-assisted turning can obtain a lower surface roughness and have good machinability.

Vocal Fold Vibration Characteristics during SOVTE using a Vibration Simulator and Digital Kymography

Objectives: The purpose of this study is to investigate the characteristics of vocal fold vibration during sustained vowel /a/ phonation and various semi-occluded vocal tract exercise (SOVTEs) using a vibration simulator and digital kymography (DKG).Methods: A total of 12 normal young speakers (6 males, 6 females) aged 20-30 years participated in the study. They phonated a sustained /a/ vowel and performed SOVTE. The vocal fold vibration characteristics were measured according to the number of vibration sources (single vs. double), and vocal tract occlusion degree using a vibration simulator and DKG. Glottal gap quotient (GQ, %), speed quotient (SQ, %) and amplitude (pixel) were estimated quantitatively from the DKG image.Results: The results showed that significantly higher GQ (p = .000) and SQ (p = .000) were observed in the humming and bilabial fricative /β/ compared to open vowels. The amplitude was significantly higher in the open vowel /a/ than in humming (p = .018) and bilabial fricative /β/ (p = .003). Also, when comparing the vocal fold vibration parameters according to vibration type (single source: straw phonation vs. double source: straw phonation with water), the double source presented a significantly higher GQ (p = .000) as well as SQ (p = .008) in comparison with a single source.Conclusion: SOVTE showed a glottal gap that is different from the opened vowel /a/. It also had a longer opening of the vocal fold and a smaller amplitude than the vowel. This suggests that SOVTE may be helpful for facilitating vocal fold vibration and good voice quality in clinical practice. The current study can be meaningful in providing theoretical and clinical evidence for SOVTE.

On the application of estimation and correction algorithms in the system for measuring vibration parameters of aircraft structural elements

Nowadays, high-precision measurement of aircraft vibration parameters during its main operations modes, including in-flight operation mode, is still considered an important scientific and technical field of study and research. These kinds of measurements are usually conducted in order to analyze the airplane vibration properties and characteristics, which serves in diagnosing the state of its structure, predicting the appearance and development of defects and deformations, as well as to prevent or avoid the influence of dangerous phenomena such as flutter, buffeting, etc. In this article, the authors present the primary results of their work to build a system designed to measure such airplane vibration parameters. In comparison with the existing analogous systems, the new proposed system makes use of traditional vibrometric measurement methods in combination with approaches typical for solving orientation and navigation problems. So, the article discusses the principles of constructing a measurement system of vibration parameters of aircraft structural elements using the example of a system for measuring aircraft wing vibrations using MEMS IMU units and data fusion technology. A brief review of the main existing solutions in this research field is carried out, and the relevance and expediency of the proposed version of the system is substantiated. The basic components and structure of the proposed system are presented, including MEMS IMU units, a displacement sensor, and an onboard navigation system. The basic principles of the system operation are described based on the use of data from the displacement sensor, inertial measurements and optimal Kalman estimation. The main algorithms for the system operation are presented, including algorithms for inertial measurements, estimation and correction, as well as the actual algorithm for calculating vibration parameters. In addition, the mathematical errors models of the main measurements units of the system are presented. The article also presents simulation results, which are encouraging, and they demonstrate the performance of the system and its expected relatively high accuracy characteristics, which in turns confirms the expected efficiency of its application and the prospects of the chosen direction of research and development.

Monitoring System of Vibroacoustic Parameters of a Working Zone

This article discusses the safety problems of the use of aviation technology associated with the influence of operational vibration of aircraft. The topical issue of timely detection and prevention of a dangerous state of critical machines and mechanisms is analyzed. Modern means of measuring vibration parameters, principles of measurement, as well as characteristics of the sensitive element of the measuring transducer, are considered. The block diagram and operation algorithm of the proposed system for monitoring vibroacoustic parameters, which is built on the basis of a piezoelectric transducer, is presented. This system can measure the parameters of noise and vibration and analyze the measured data, signal about exceeding the permissible ranges for human work, display the measured data. The advantage of the proposed system is the connection of the measuring channels with the mainboard using the Bluetooth module, which allows the sensors to measure noise and vibration to be placed in any part of the working area.

ANALYSIS OF THE capabilities OF the CLOSED-OPEN SYSTEM CORRECTION scheme FOR MEASURING VIBRATIONS OF AIRCRAFT STRUCTURal ELEMENTS

В настоящее время в связи со всевозрастающей степенью сложности проектирования, производства и эксплуатации летательных аппаратов все более важным направлением в области развития информационно-измерительных систем становится совершенствование существующих и разработка новых способов измерения параметров вибрации элементов механических конструкций летательных аппаратов. Целью данной работы является анализ возможности и перспективности построения системы для измерения вибраций элементов конструкции самолета на основе использования микромеханических инерциальных измерительных блоков в качестве основных виброметрических измерителей. При этом объектом исследования является система измерения параметров вибрации, а предметом – ее структура, состав, алгоритмы функционирования и ожидаемые точностные характеристики. Для достижения поставленной цели строится информационно-измерительная система на базе инерциальных приборов, а также датчиков для непосредственных измерений перемещений, используются численные и аналитические методы высшей математики и теоретической механики, методы теории случайных процессов и оптимального оценивания. В статье рассмотрены принципы построения такой системы на примере варианта системы измерения параметров вибраций крыла самолета, представлен краткий обзор существующих решений в предметной области и обоснована актуальность и целесообразность предложенного варианта технического решения. Приведены базовый состав и структура системы, описаны основные принципы ее работы, основанные на использовании данных датчиков перемещения, инерциальных измерителей и оптимального калмановского оценивания и коррекции. Показаны основные алгоритмы работы системы, включая алгоритмы ориентации и навигации, оценивания и коррекции при замкнуто-разомкнутой схеме включения оптимального фильтра Калмана, алгоритм вычисления параметров вибрации, представленыматематические модели ошибок основных измерителей системы, показаны полученные предварительные результаты имитационного моделирования, демонстрирующие работоспособность системы и ее ожидаемые приемлемые точностные характеристики, подтверждающие возможность эффективного использования системы и перспективность выбранного направления работ. At present, because of the ever-increasing degree of complexity of aircrafts design, production and operation, the improvement of the existing methods and development of new ones for vibration parameters measurement of aircrafts mechanical structural elements is still an important direction in the field of information-measurement systems development. The purpose of this work is to analyze the possibility and prospects of constructing a system for measuring vibrations of aircraft structural elements based on the use of micromechanical inertial measurement units as the main vibrometric transducers. In this case, the object of research is the vibration parameters measurement system, and the subject is its structure, composition, operations algorithms and the expected accuracy characteristics. To achieve this purpose, an information-measurement system is built on the basis of inertial devices, as well as sensors for direct displacements measurements, numerical and analytical methods of higher mathematics and theoretical mechanics, methods of random processes theory and optimal estimation are used. The article discusses the principles of constructing such system taking as an example a system for measuring the vibration parameters of an aircraft wing, provides a brief overview of the existing solutions in this field of applications and substantiates the relevance and expediency of the proposed methodology of the technical solution. The basic components and structure of the system are presented, the basic principles of its operation are described, based on the use of data from displacement sensors, inertial meters and optimal Kalman estimation and correction. The main algorithms of the system operation are shown, including the orientation and navigation algorithm, estimation and correction algorithm for a closed-open scheme of optimal Kalman filter inclusion in the system, algorithm for calculating vibration parameters, beside the mathematical errors models of the main system sensors and channels are presented, preliminary results of simulation modeling are shown and they demonstrate the operability of the system and its expected acceptable accuracy characteristics, confirming the possibility of the effective use of the proposed system and the prospects of the chosen direction of work.

Electrical Characterization Method for Resonance Performance of Photo-Elastic Modulators

As a kind of resonant device, the modulation efficiency of the photo-elastic modulator (PEM) is determined by its inherent resonance characteristics, including the resonance frequency and quality factor (Q-factor). The existing methods used to characterize the resonance performance of the PEM are mainly based on the optical method to measure the vibration parameters, but these methods are more complex, have a high cost, and are not able to accurately measure the quality factor. Therefore, this paper proposes an electrical characterization method based on impedance measurement. In this method, an equivalent circuit model for the PEM is established. By measuring the impedance vs. frequency curve of the PEM and using the equivalent circuit model for fitting analysis, we can obtain the parameters of the equivalent circuit model. With these parameters, we can eventually calculate the natural resonance frequency and quality factor. The above method was applied to some commercial PEM products for experimental verification. The experimental results show that this method can accurately measure the natural resonance frequency and quality factor of the PEM, and the error is less than 0.03%.

Vibration parameters and indicators of a dynamic tillage tool

According to domestic and foreign research on the efficiency of active and passive vibrating tillage tools, the created vibration allows reducing the traction resistance of tillage implements compared to conventional tools, while improving the tillage quality. The study aimed to determine several vibration parameters and indicators of a dynamic tillage tool supplied with an energy storing and transmitting device: frequency and amplitude of oscillations, absolute velocity, vibration velocity, acceleration of vibration, a force of inertia, and oscillation energy. The study applied the energy assessment methods of tillage tools with the measuring and information system designed at IEEP – branch of FSAC VIM; analysis and generalisation of experimental data. Vibration variables were determined by the strain-gauge method. The study revealed a significant effect of oscillation frequency and amplitude of the tillage tool, depending on the machine travel speed and characteristics of elastic elements, on its vibration velocity and acceleration, the force of inertia and the energy of oscillations.The total increase in these forces owing to a high-frequency dynamic impact may affect the soil layer considerably as an additional loosening. The accumulated impact energy can provide a decrease in the traction resistance of the tillage tool.

Estimating efficiency of forecasting technical conditions of ship propulsion systems

The article considers an approach to assessing the effectiveness of the most common methods of predicting the technical conditions and failure with reference to the ship shafting. There have been analyzed the main factors in operation of the ship shaft line, which cause the change in its technical state. It has been found that a special feature of some loads acting on the propeller shaft is their stochastic or changing nature over time, which hampers predicting the technical state of the shafting and its units. The features of stochastic and extrapolation forecasting methods have been analyzed. The possibility of using statistical methods in conditions of mass standard production of shafting units with a relatively short regulated service life is estimated. An extrapolation method is proposed for predicting the maximum permissible clearance of stern tube bearings. The case of accumulating samples of measuring results of the propeller shaft sagging in the given time intervals is considered, the approximating functions are constructed. The criteria for the reliability of the results of extrapolation methods for predicting the wear of stern tube bearings are determined. There have been developed the proposals for adapting the causal method as an alternative to the extrapolation method. A schematic diagram of a system for the ship shafting failure predicting has been developed using the registration and analysis of vibration parameters, which serves as the basis for constructing a regression model of damage accumulation. The proposed forecasting system allows studying the actual operating conditions of the shafting, defining the actual external loads and the regularities of their occurrence, measuring deformations and stresses, and determining quantitative indicators of the reliability of the shafting during normal operation and special operating modes, for example, with vibration resonance. The theoretical basis of the algorithm for calculating and registering loads affecting the service life of shafts is proposed.