Research On Monitoring Corrosion And Humidity Method Based On Fiber Grating Sensor

Aerospace structures are often exposed to the environment corrosion is one of the main reasons make it performance degradation, like acid, alkali and wet fog. Corrosion monitoring of aerospace structure detection needs to carry on the premise of not destroying the structure mechanical characteristics If the sensor is not timely warning, Serious safety accidents would happen. If the monitoring result is error, there will be the waste of resources and some parts would be replaced when they still can continue working. Therefore, in order to maintain the structure and reduce the loss of state property, providing a safe and reliable method of corrosion monitoring is very important.Fiber optic corrosion sensor is the combination of corrosion detection and optical fiber sensing technology in recent years. It has a unique advantage, like high sensitivity, light weight, anti-electromagnetic interference, corrosion resistance. Therefore, this paper is about the research on the corrosion sensing and humidity monitoring technology based on optical fiber sensing technology, the main work includes the following aspects:Firstly, for the needs of aerospace field corrosion of aluminum alloy, making research on preloaded types corrosion sensors on the aluminum alloy. The optical fiber grating corrosion sensing properties of sheet structure and aluminum tube structure is studied. Giving out the principle of the aluminum alloy corrosion monitoring, Get the theoretical relationship model between the fiber grating reflective spectrum of offset and aluminum alloy corrosion. The optical fiber grating corrosion monitoring test system in acid-base environment is constructed to verify the feasibility of the two kinds of corrosion sensor.Secondly, aiming at the problem of that mechanical structure of aluminum alloy is easy to be corroded in acid and alkali salt fog environment, researching on a kind of aluminum alloy corrosion sensor and analyzed the principle of corrosion monitoring. The adhesion between the aluminum film and fiber Bragg grating has been tested after water bath experiment. The temperature sensing characteristics of fiber grating are studied after aluminized. The stability and sensitivity of corrosion sensor are improved by annealing. The optical fiber grating corrosion monitoring test system for strong acid environment is constructed to verify the effect of the corrosion monitoring sensorFinally,According to the industrial and agricultural production environment humidity measurement requirements, researching on the humidity sensor base on the coating PI film on the gate area of the fiber grating. The preparation technology of PI film is optimized. Put the PI to coat on the gate region after it dissolved in DMF. The principle of fiber Bragg grating humidity sensor is analyzed. Temperature compensation correction parameter is got after researching of temperature sensitive characteristics of humidity sensor. In addition, the humidity sensor repeatability and hysteresis are also studied.