Research On Structure Damage Detection Method Of Hypersonic Vehicle Heat/Force Coupling Field Based On Fiber Bragg Grating Sensor

Hypersonic vehicle is a commanding point in the field of aircraft technology.In a series of experiments at home and abroad,many problems have occurred,which have affected the success of the experiment.Due to the lack of corresponding means to obtain key information,these problems are difficult to predict in advance,and it is difficult to carry out a valid analysis afterwards.After decades of development,structural health monitoring technology,which began in 1954,has become an effective monitoring technique to identify structural health status and damage.However,the traditional sensors used to obtain data in the structural health monitoring system are not very suitable for the compact airframe and special service environment of hypersonic aircraft.At present,the research on the damage of hypersonic vehicle structure is not enough,so it is difficult to diagnose the damage in real time by combining the data.In this paper,the force / heat coupling field of typical hypersonic aircraft fuselage segment structure is studied by using fiber grating sensor,which lays a foundation for the state monitoring and damage diagnosis of the aircraft.Firstly,the structure of typical hypersonic aircraft fuselage section is analyzed and simplified.The finite element calculation and experimental analysis are used to verify each other.The simplified model of adding damage is studied,and the strain law around the damage is obtained.Secondly,according to the requirement of hypersonic vehicle structure temperature measurement and its influence by heat,a reverse indirect bonding method is proposed to paste fiber Bragg grating sensor,so that the temperature sensor can measure the temperature information of the structure.Effectively avoid the effect of surface strain on the structure;At the same time,according to the principle of heat transfer,the interpolation method is proposed to reconstruct the temperature field,and the layout of the sensor network is optimized.Finally,the virtual boundary method is proposed to further optimize the reconstruction of the temperature field.Then according to the characteristics of mechanical / thermal coupling of hypersonic vehicle structure,a double fiber decoupling method is proposed to study the strain of the structure at different temperatures,so as to obtain the temperature load and mechanical load.The law between structural damage.Finally,the damage verification experiment of hypersonic aircraft shrinkage test piece is carried out in hypersonic wind tunnel,the practicability of fiber Bragg grating sensor is tested,the experimental results of plate are calibrated,and more damage effect rules are obtained.Based on the characteristics that fiber grating sensors are small and multiple sensors can be integrated on a single optical fiber,the damage information of aircraft structure is obtained effectively by a new acquisition method,and the damage law is analyzed.It lays a foundation for the state monitoring and damage diagnosis in the aircraft structure integrated with load and thermal protection.