The Diagnosis Of Hypersonic Structure Damage Based On FBG Sensor

Hypersonic aircraft is the world all countries including the United States compete to develop a new kind of aircraft which has great application potential. At present, its development is in the stage of experimental study, the United States has developed including X-51 and a series of hypersonic aircraft, which in many flight test has undergone a lot of problems keep the test out of success, due to the lack of access to key information, these problems are difficult to see, it is difficult to analyze; also can be used repeatedly is a an important development direction of hypersonic aircraft. So the construction of system based on structural characteristics, real- time information on aircraft health monitoring is a key problem of hypersonic flight test and subsequent development. In this paper, the hypersonic aircraft bearing and thermal protection structure as the research object, on the structural damage diagnosis technique based on fiber Bragg grating sensor was studied.Analysis of the hypersonic aircraft structure and function characteristic, structure analysis method to diagnosis key structural characteristics data and the structure parameters of acquiring means, for hypersonic aircraft characteristics of the structural damage diagnosis system framework based on FBG sensor, clear the system should have high integration, data sampling rate is high, the sensor is strong the key characteristics of anti-jamming.For hypersonic aircraft common structure form, the natural frequency of the radial basis function neural network combined method for determining beam structural damage location and degree. The method can accurately identify structural damage location, and can evaluate the damage depth of cut injury. Considering the effect of temperature on the structure of elastic modulus, the temperature as the adjustment of neural network input and output weights, finish the identification of damage location thermal structure.The hypersonic aircraft skin structure carried out the test on the structural damage diagnosis technology based on FBG. The bare fiber grating sensor performance and the damage to the fiber Bragg grating sensor responses were studied. Static tensile test results show that the sensitivity of optical fiber grating sensors is different for the skin structure of different installation forms adhesive and different will greatly affect the sensitivity of the sensor. Open the groove structure that does not affect the structure properties can ensure the stable performance of FBG sensor, Fiber Bragg grating sensor for damage hole skin added after loading the stress concentration is very sensitive, was consistent with the result of numerical simulation. The stress concentration zone of sensor reflection wave form changed obviously, so the sensor reflection chirp wave regularization bandwidth can be the damage location is effective in identifying.Hypersonic structural damage diagnosis system based on the demand, studies to get the damage diagnosis required modal test data of the FBG distribution of measuring points, criterion on the structure and material of titanium alloy she ll structure modal test sensor selection were calculated to ensure application mode, through the improved algorithm, avoiding the initial measuring point select the required for matrix QR decomposition, enhances the efficiency of operation.