Design And Research On Fiber Bragg Grating Vibration Monitoring System

The complex dynamic problems exist in our daily life, so the state of vibration is extremely complicated. Abnormal vibration of the building or equipment often lead accident and bring enormous casualties and losses to human beings. If we can examine the exist danger before the accident occur and make appropriate and timely protection, we can protect our lives better. Therefore, a set of comprehensive vibration monitoring system compels in the eyebrow. Through high-quality analysis and testing to the vibration signal, we can learn about the condition of the equipment structure vibration, from which we can understand some common equipment failures. Thus, we can guarantee that the equipment works securitly, which is very significant to our economic and social.As early as the beginning of the twentieth century, researchers have carried out testing and research of vibration. The traditional vibration monitoring system use electromagnetic acceleration sensor. There is less resistance to electromagnetic interference, and the transmission distance is so short that it's not easy to remote monitoring. With the large-scale engineering structures, its dynamics become more and more complex, and the shortcomings of the electromagnetic sensors are increasingly obvious. The electromagnetic sensors are increasingly unable to meet the needs of large-scale projects vibration monitoring, which greatly restrictes the level of safety assessment of vibration monitoring techniques. In this topic, we design a set of vibration monitoring system which based on fiber Bragg grating accelerometer. In the system, fiber Bragg grating accelerometer will be fixed to the vibrating object. The sensor will vibrate when the object vibrate, and then vibration signals will be input to the fiber grating vibration demodulator, which demodulate the optical signal and make it convert to electrical signal. After that, the electrical signal will be amplified and filtered by charge amplifier. Then collector will collecte it and input it into the computer. Our own vibration monitoring software will analyze and process the signal, and extract information about the state of vibration, such as waveform, spectrum, speed, acceleration and displacement, so as to monitor the vibration condition successfully. The system uses fiber Bragg grating sensors, which is not only to overcome the defect of traditional anti-electromagnetic interference, and has many other advantages such as good electrical insulation, intrinsically safe, high sensitivity and response speed, measuring object widely and so on. And in this system we use double-grating matched filter demodulation technique. The outside temperature changes, which lead center wavelength of the two grating drift in the same direction. And make self-compensation of temperature possible. The two grating which involved in sensing greatly improve sensitivity. The software functions of the system is also extremely comprehensive. Through analysis of vibration signal in time domain and frequency domain, we can obtain vibration parameters. And with VisualC++compiler, we can achieve a comprehensive monitoring of vibration, which has laid a good foundation for our advanced prevention.