Research Status and Development Trend of Mechanical Vibration 5

Since the 70s of the 20th century, the rapid development of electronic technology and signal processing technology, and the continuous deepening of the research on the dynamic characteristics of the rotor-bearing system, have effectively promoted the development of condition monitoring and fault diagnosis technology of large-scale rotary machinery, and continuously improved the technical level of condition monitoring and fault diagnosis of large-scale rotary machinery.

The state vibration monitoring and fault diagnosis technology of large-scale rotary machinery mainly includes the development of rotor vibration monitoring system, vibration signal processing and analysis technology, rotor fault diagnosis technology, etc.

Rotary machinery condition monitoring is divided into two ways: offline regular monitoring and ** monitoring. Off-line periodic monitoring begins with the collection of rotor vibration signals with a tape recorder or data collector. It is then sent to a spectrum analyzer such as CF940, SD375, etc. for analysis.

**Monitoring is to continuously record and monitor the vibration signal of each measurement point of the unit, and once the unit fails, the vibration signal of the unit at that time can be obtained. Foreign countries pay great attention to the development of large-scale rotary machinery condition monitoring and fault diagnosis equipment, whether it is used for offline monitoring and monitoring have more mature products for selection, such as Japan and Denmark production of tape recorders, the United States Atlanta company M777 portable data collector, signal processors are common H P, B&K, Ono company products. **The monitoring system is mainly composed of industrial microcomputer system and special instruments based on microcomputer processor, which can monitor the vibration signal of dozens or hundreds of channels of the rotor in real time at the same time, such as the TDM and DDM series products produced by Bentley Company and the M6000 series products produced by Atlanta Company.

Some large domestic enterprises have introduced some large-scale rotary machinery condition monitoring instruments, which has broadened everyone's horizons and promoted the development of domestic large-scale rotary machinery condition monitoring and fault diagnosis technology. The outstanding disadvantage of imported monitoring instruments is that it is expensive, and it is difficult to maintain and improve the update, so it is impossible to popularize it in our country. Harbin Institute of Technology developed the "microcomputer to unit vibration monitoring and fault diagnosis system MMMD-1", Xi'an Jiaotong University and Zhenhai Petrochemical Plant jointly developed "large rotating machinery calculation status monitoring and fault diagnosis system", etc., these systems have a high performance ratio, and the actual situation of Chinese enterprises is closely integrated, is conducive to the promotion in China, and has achieved good results.

The development of a large-scale rotary machine monitoring system based on a personal computer has also received international attention in recent years.

This topic is too big, involving the optimal design of mechanical structure, vibration modal test, monitoring, fault diagnosis, environmental vibration test, etc., as for the present and development trend, I personally feel that at least these aspects are involved: the system is larger and more complex, and more related fields of technology are more closely combined, relying on the technical achievements in various fields, and there are still many problems that have not been effectively solved. We hope that the experts will be generous in answering their questions.

1656 1657, C. of the NetherlandsHuygens first proposed the theory of physical pendulum and created a single-pendulum mechanical clock. At the beginning of the 20th century, the main concern of mechanical vibration was the avoidance of resonance, so the focus of research was on the determination of the natural frequencies and mode shapes of mechanical structures.

In 1921, H. in GermanyHolzer proposed a calculation method to solve the natural frequencies and mode shapes of the torsional vibration of the shafting system. In the 30s, the research on mechanical vibration began to develop from linear vibration to nonlinear vibration.

Since the 50s, the study of mechanical vibrations has developed from regular vibrations to irregular vibrations that can only be described by probability and statistical methods random vibrations. Due to the development of automatic control theory and electronic computers, the calculation of multi-degree-of-freedom systems, which was considered difficult in the past, has become an easy problem to solve. The development of vibration theory and experimental techniques has made vibration analysis an important tool in mechanical design.

3. The dynamic characteristics of mechanical equipment can only be analyzed and studied on the basis of known dynamic models, external excitations and working conditions. Dynamic analysis includes: Calculation or determination of intrinsic properties such as natural frequencies, modal shapes, stiffness, and damping of various orders of mechanical equipment.

Based on the intrinsic properties, it is possible to identify the causes of vibrations, avoid resonances, and provide the basis data for further dynamic analysis. Calculate or measure the dynamic response of the displacement, velocity, acceleration, phase, spectrum and vibration time history of the relevant points when the mechanical equipment is excited, assess the ability of the mechanical equipment to withstand vibration and impact according to the dynamic response, find its weak links and waste links, and provide a basis for improving the design. It is also possible to establish equations of motion for mechanical systems expressed in terms of modal parameters, known as modal analysis.

Analyze and calculate the dynamic stability of mechanical equipment, and determine the instability of mechanical equipment, that is, the critical condition for self-excited vibration. Ensure that the mechanical equipment does not produce self-excited vibration under the condition of giving full play to its performance, and can work stably.

According to the meaning of the question, you can draw a waveform diagram when t=4s.

Then, you can judge that B is correct, and if you have any questions, you can ask Lu Jing, thank you for accompanying Zhongshen.

The "2011-2012 China Vibration Equipment Industry Development Research Report" released by China Industry Information Research Network mainly analyzes the industry situation objectively and fairly from the current situation of the domestic and foreign markets and the development background of China's vibration equipment industry, market production supply and demand, competition pattern, brand building, channel development, and strategy, and speculates the future market size through scientific mathematical models, and gives suggestions for the development of the industry. This report will show customers a complete panorama of the vibration equipment industry, and provide high-quality market information services for business decisions.

China Industry Information Research Network has a professional research team and analysis experience, each research report is written by a team member with rich research experience, and a professional report reviewed by senior experts, which can provide customers with comprehensive, objective and reliable market analysis and industry development trend opinions, which is an important basis for scientific decision-making by various related enterprises.

1. Vigorously strengthen the research on the theory and technology of vibration machinery, on the one hand, carry out in-depth research on the basic theory and working mechanism of vibration machinery, such as strengthening the theory of nonlinear vibration machine, the stability of vibration, etc., on the other hand, strengthen the application of practical technology, such as the study of screen surface wear resistance and prolonging the life of the screen machine.

2. We should vigorously carry out the research and development of the practical application of vibration machinery, expand the application field and scope of vibration technology, and widely use vibration machinery in various fields and various processes.

3. In particular, it is necessary to strengthen the combination of vibration machinery technology and information technology, that is, multi-coal technology, integrated circuit technology, optical fiber technology, network technology and artificial intelligence technology, so that the theory and technology of vibration machinery can become a high-tech based on intelligence.

The reciprocating motion of an object or particle near its equilibrium position.

Vibrating machinery is a mechanical vibration transmitted through an elastic medium, and the reciprocating motion of an object or particle near its equilibrium position. The motion of table tennis is a mechanical motion because there is a balanced position.