Study On Fiber Bragg Grating Sensor System For Measuring Mechanical Parameters Of Ice

Ice is widely distributed in nature, and it is not just an important source of fresh water, but also an important part in the natural environment of human life, which has a decisive influence on the environment and human beings, because of that, it is necessary to study the physical and mechanical properties of ice. Results of the traditional static test mode are unstable and traditional static test mode is difficult to meet the actual test conditions, however there have been many applications and researches of FBG in detection and monitor for materials, which shows a great advantage of FBG, and it becomes a new trend to test properties of material, thus carry out related research has important significance.In view of the fiber grating has the advantages, such as small volume, anti-electromagnetic interference, high sensitivity of sensing, based on reading a lot of literature, the research to test mechanical parameters of ice with the help of fiber grating is proposed to carry out, paper specifically contains the following elements:First of all, the domestic and international research progress and the background for testing mechanics parameters of ice are introduced; secondly the significance and selected topic basis of the paper is briefly described.Secondly, the structure and sensing principle for the fiber grating has been described, in which the fiber Bragg grating sensing properties of temperature and strain have been detailed theoretical analyzed. Then the whole principle for testing mechanical parameters of ice is analyzed theoretically, in this part, the summary of the characteristics for ultrasonic wave propagation is provided, and then the relationship between the ultrasonic velocity and other physical parameters of the object is analyzed in detail, thus the relationship between ultrasonic velocity and Young modulus, Poisson’s ratio, shear modulus and bulk modulus of ice sample is derived, and conclusion,by testing ultrasonic wave propagation velocity in the ice sample to determine related mechanical parameters of ice, is obtained.Then, the holistic system architecture is introduced, and then the demodulation part of system is detailed analyzed and emulated. After the introduction of the whole system, the main components of the system were introduced. The experimental specific operating procedures and setting of test system are described, test results and analysis are divided into four part: in the first part,the response of the grating to different ultrasonic frequency and amplitude has been showed; in the second part, velocity of ultrasonic wave versus temperature of ice has been measured; in the third part, after the conversion of the measured parameters by the formula, mechanical parameters of ultrasonic wave versus temperature of ice has been obtained; and finally error analysis and summary for the entire experimental has been gotten.Finally, the main works and conclusions in the thesis are summarized, and then several recommendations to improve the system are proposed.