Research On The Arrangement Method Of FBG Sensor Array In Impact Localization

Aerospace equipment is often hit by other objects during flight,such as space debris,hail,birds and bomb strikes,resulting in damage to the surface or interior of the equipment.If the impact position can be located in time,the detection efficiency can be greatly improved when the equipment is repaired in a large area in the later period.Most of the aerospace equipment is made of aluminum alloy materials.Fiber grating(FBG)sensors are widely used in the health monitoring of aerospace equipment because of their advantages of easy networking and antielectromagnetic interference.At present,FBG sensor array pasted on the surface of aluminum alloy structure for impact monitoring is widely used.In most studies,the sensitive characteristics and range of sensors are not considered,but the sensitive range is simply defined as a square,and then the tight layout of square is used to complete the layout design of sensor array.which results in low sensor utilization,inaccurate localization results and other problems.Therefore,based on the FBG sensing principle,this dissertation studies the strain transfer characteristics of the FBG sensor under the impact load,and focuses on the impact localization of aluminum alloy materials,and puts forward the arrangement optimization method of FBG sensor array in impact localization.First of all,this dissertation introduces the sensors used in impact localization and the research status of these sensors,and proposes that the accuracy of impact localization has a great relationship with the placement and number of sensors,and summarizes the layout of FBG sensor network in impact localization.Secondly,the simulation software is used to simulate the process of the steel ball hitting the aluminum alloy plate,and the 10 mm position at the center of the back of the plate is used to represent the position of the FBG sensor,and the strain distribution at this position is recorded.The strain transfer characteristics of FBG sensor are analyzed,and the sensitive range of FBG sensor is obtained.According to this sensitive range,four FBG sensor array paste schemes are innovatively proposed,sample points in the simulation model are impinged,strain data at sensor locations are recorded and decomposed by wavelet packet,energy feature vectors of each frequency band were extracted and a sample library is established.The points with different distances near the reference point are taken as test points,and the impact signal is collected in turn.These distances can replace the error influence introduced in the actual impact process.The similarity between the test point and the sample point is compared to determine the localization position of the test point,and the localization accuracy of the four arrangements under different errors can be compared.Finally,the experiment of steel ball impacting aluminum alloy plate is carried out,and the impact experiment of FBG sensor is carried out from different distances and angles to verify the strain transfer characteristics and sensitive range of the sensor in all directions.The fundamental frequency interference of the impact signal is removed,the sample library is established,and the similarity is compared by using wavelet packet decomposition technology and wavelet packet signal amplitude energy feature extraction method.The accuracy of the localization results of four paste schemes is compared,which lays a foundation for the subsequent impact localization research of other materials.