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Vibration and Noise Elimination

#A-1018


Technology of Vibration and Noise Elimination of Mechanical Systems

Tech Area / Field

  • MAN-MCH/Machinery and Tools/Manufacturing Technology

Status
3 Approved without Funding

Registration date
29.04.2003

Leading Institute
Scientific-Production Open Joint Stock Company "Interstanok", Armenia, Yerevan

Project summary

The Present Project is dedicated to problems of Mechanical Systems’ Noise and Vibration Elimination technology, such as Machines, Aircraft Gas Turbine Engines, Gyroscopes, Big Electro-motors and Generators, Vacuum Cleaning Units, Gears, small and micro-electro-motors, motor-gears, bearing units of tail transmission of helicopters and etc. This technique has appeared lately, based on technical, particularly on vibration-acoustic diagnostics of mentioned mechanical systems.

Two directions have precisely distinguished in vibrato-acoustic diagnostics:

– the experimental, based on application of characteristic defects and measuring of their displaying as a vibrating or acoustic signals;


– the theoretical, based on development of vibration models, which are confirmed by further experiments;
– SPOJSC “INTERSTANOK” has implemented some contract works with different organizations of former Soviet Union, such as Moscow Aviation Institute, Military Organizations of Leningrad, factories of Krasnoyarsk, Voronezh, Lipetsk, Kazan, etc.;
– collaboration within the project framework intended between some partners - leading specialists of Brul and Cair Company and the group of specialists of Laboratory of Vibration-diagnostics of SPOJSC “INTERSTANOK” possesses considerable scientific-technical experience in the solving of similar problems. Submitted project meets the requirements of International Scientific-Technical Centre and necessitated by creating of alternative vacancies for scientists and engineers were engaged in Military programs of Soviet Union.

The purposes of the Project.

The main issue of vibrato-diagnostics is the searching of faultiness indicating locations and the reasons of their appearance. But till now only one component of vibration’s spectrum caused by imbalance of rotating details, is provided with technologies and equipment (also automated) /18/. Eliminating of other unbalanced forces (sources of vibration) in wide range of frequencies usually is not foreseen. This project is called to fill this gap. Trustworthiness of vibrato-diagnostics mainly depends on accounting of different defects interaction, which cause the effect of amplitude modulation, namely an appearance of lateral components (strips) around the bearing component /3/. Comparison of calculated and experimental spectrums exactly indicates the presence of any defect. In experimental spectrums, for example, often appears the components which indicate the presence of hoop’s warp of bearings after their installing, caused by defects conjugated with hoops of bearings’ details - non-perpendicularity of faces of housing’s for immovable hoops and shoulders of shafts for bearing baffles, etc. /2/. It should be mentioned that the frequency characteristic is the main one from three spectral characteristics for defect identification. It means that detection and distinguishing of defects (identification) is firstly executed by the frequency of vibration components, generated by them. After the vibration spectrum has been obtained, the frequencies of components are being compared with the frequencies of theoretical model and on this base the identification of defects and their revealments is taking place. Development of new theoretical and experimental background for diagnosis of complicated mechanical systems with the purpose of constant defects’ exposure - defects, caused by unqualified manufacturing and breaches of manufacturing process, which bring to mechanical objects’ noise and vibration increasing. High- precious CNC machines, flying objects of aviation and other mechanisms, which are widely used in different systems of modern science and technique, are belong to above mentioned systems. The main problem is to develop universal methods of single and multiple constant faultiness diagnosis for definite class of mechanical systems, where the problem of diagnosis by identification of out-coming signals of vibrato-sensors and noise characteristics is solvable.

Solution of diagnosis problem of mechanical objects and reducing the level of vibration noise has not scientific-technical character only, but also promotes the solution of working staff’ health and environmental problems.

Relevance of the Problem. The Twenty First Century – it is an era of innovation investments and high technologies, requesting high requirements to the quality of technical devices and reliability of their functioning in cases of different conditions of exploitation. These conditions require constant development of diagnosis methods and devices, as the direct method of mechanical system defect identification both in process of manufacturing and exploitation. Despite of achieved results of many known foreign and domestic companies involved in auto-making, machine-making, aircraft-making, space navigation systems, the problem of continuous mechanical systems’ diagnosis is still unsolved for definite conditions connected with complicity and variety of technical devices. It should be mentioned that most of published scientific works are mainly dedicated to the problems of discrete action system diagnosis. These are mainly electronic digital devices described by methods of Boolean algebra where the well-known methods of discrete mathematics are successfully used. As to systems of continuous action, such as mechanical systems, theses are considerably less researched and practically there are no any publications concerning diagnosis of multiple undistinguished continuous faultiness, simultaneously acting on out-coming spectral picture of researched system. It is known that in some case faultiness of definite class of mechanical systems cause considerable financial and human losses. Therefore the problem of continuous systems’ diagnosis is still actual and demands constant development. In this context research-investigation works are being carried out to develop new methods and devices of mechanical objects’ diagnosis. So the improvement of mechanical units’ manufacturing and assembling processes in case of automotive production depends on the reliability of above mentioned works’ results. American, European and Russian scientists made considerable progress in this field, and their developments are implemented in some fields of industry. But researches on improvement of diagnosis methods and devices for mechanical systems with the purpose of enhancing reliability and diagnosis informativity with low risk and investments of theoretical and finance assets, are still in programs of many scientists and specialists involved in modern diagnostics. The existing experience of military scientists, as well as of technicians participating in this project and preliminarily received results of experiments guarantee the success of target purpose.

Expected results. As the result of the project implementation the following problems will be solved.

- Development of mechanical systems vibrato-diagnostic methodology on the base of spectral analysis of their vibration frequency and acoustic signals;


- Mathematical simulation of vibrations, excited by different defects, including assembling defects in the process of bearings mounting. Simulation is executed by kinematics of mechanical system or its separate module considering presence of processing defect of manufacturing and assembling;
- Analytical description of some relevant defects of rotary machines and gearing. It should be mentioned that defects might be singular, plural, symmetrical, as well as defects originated in process of machines operation;
- Application of spectral analysis for detecting of some covert defects. Cepstrum is especially effective in case of presence of low-frequency components of spectrum;
- Composition and structure of automated system of vibration diagnostic. Automated system of vibration diagnostic, principles of which are given in /2/;
- Considering of Amplitude modulation for reliability increasing of vibration diagnostic. Amplitude modulation is a result of interacting of different defects of rotating elements of machine and brings to appearance of side components of frequency strips, which increase the reliability of diagnostic /15/;
- Integration of Armenian scientists in the International scientific community, re-orientation of specialists, who was involved in military researches, for the solution of peaceful problems.

The main technical approaches for fulfilment of experimental-theoretical works are the following.

- Application of vibrato-acoustic diagnostics, among other existing methods of definition of technical status of mechanical systems, with condition that informational signal will be analyzed by narrow-band filters, because only in that case the response of defect appears as determined component of spectrum of vibration. The frequency of this component is being compared with frequency of calculated spectrum and probable defect of manufacturing or assembling is being defined. Parallel analysis of vibrato-acoustic signal of noise and its comparison with vibrato-spectrum picture will allow receiving an information about assembling and manufacturing defects of machine, which are sources of vibration and noise.


- The novelty of our approach is in application of automated system of vibrato-diagnostics as a tool for finding of constantly repeating defects and by action on appropriate manufacturing operations to eliminate vibration and noise of mechanical systems.

For theoretical investigations the following will be used:

- theory of mathematical simulation of mechanical systems kinematics considering technological defects of manufacturing and assembling;


- methods of spectrum analysis, frequency analysis, Fast Fourier transformation;
- statistic methods of analysis, methods of pattern recognition.

The presented project, which is composed in accordance with instructions of ISTC, caused by need of creation of alternative for scientists and technicians, who earlier was involved in weaponry.

The contribution of foreign collaborators is in exchange of information during the process of project performance, mutual discussing of obtained results and assistance for integration of project’s executors in world scientific community.

Scientific Production Joint Stock Company “INTERSTANOK” possesses sufficient scientific and instrumental potential for achievement of gaols, named in project. The project is considered for 36 months.


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