CN103693209B - A kind of aircraft corrosive environment monitoring method and implement device thereof - Google Patents

Abstract

The invention discloses an aircraft corrosion environment monitoring method and a realization device thereof, which belong to the field of structural health monitoring. The monitoring method of the present invention determines the corrosiveness level of the environment by measuring a plurality of environmental parameters that are likely to cause corrosion, thereby judging the health status of the aircraft structure and guiding the maintenance to take corresponding measures. The aircraft corrosion environment monitoring device of the present invention is composed of a main control micro-control module, a measurement module, a communication module and a power supply module, has small volume and low energy consumption, and is suitable for being installed in various parts of the aircraft for long-term monitoring. The invention can change the current regular maintenance of the aircraft into on-demand maintenance, which improves the efficiency and reduces the cost.

Description

A method for monitoring the corrosion environment of aircraft and its implementation device

technical field

The invention relates to an aircraft corrosion environment monitoring method and a device for realizing it, and belongs to the technical field of structural health monitoring.

Background technique

Corrosion of aircraft structure refers to the cumulative chemical loss and damage of components over time through chemical or electrochemical action in the service environment. Its randomness is large, its types are extensive, its influencing factors are numerous and its interaction is strong, so it cannot be completely avoided. The corrosion damage of the aircraft directly affects the remaining life and is related to flight safety. However, in the early stage of corrosion, it is difficult to detect the corrosion site, and when the corrosion initiates, if it is not controlled, it will develop faster and more seriously than other damages. Therefore, it is necessary to actively prevent and control the generation and spread of corrosion.

At present, in the field of aerospace, the corrosion monitoring of aircraft mainly focuses on the research and development of anti-corrosion coatings, using various non-destructive testing techniques to discover, locate corrosion, and determine the degree of corrosion. Techniques such as ultrasonic imaging, magneto-optical imaging, and infrared imaging all find corrosion when corrosion has already occurred, and take corresponding remedial measures according to the damage. That is to say, the current focus is on the anti-corrosion design of the aircraft, as well as the detection and maintenance after corrosion occurs, while the monitoring research on the corrosion environment of the aircraft is almost blank.

The corrosion environment monitoring of aircraft mainly refers to the installation of monitoring devices in some corrosion-prone parts according to the characteristics of the aircraft structure, real-time collection of surrounding environmental parameters, and uploading to the client to establish a database after signal conditioning to analyze changes in the environment , predict the possibility of corrosion, maintain the aircraft as soon as possible, and try to avoid losses caused by corrosion.

By monitoring the corrosion environment of the aircraft, an environment-corrosion model can be constructed, the corrosion rate can be calculated according to the environmental parameters, and the corrosion status of the aircraft can be deduced so as to guide the maintenance of the aircraft, which not only reduces unnecessary shutdowns, but also ensures flight safety.

Contents of the invention

The invention provides a method for monitoring the corrosion environment of an aircraft and a device for realizing it. This method mainly uses monitoring devices to measure key environmental parameters that are likely to cause aircraft corrosion, and calculates the possible corrosion rate through a mathematical model, and then infers the corrosive level of the environment. Among them, the monitoring device integrates three sensors, which can monitor five environmental parameters related to corrosion: temperature, relative humidity, wet time, value and concentration.

The present invention adopts following technical scheme for solving its technical problem:

A method for monitoring an aircraft corrosion environment, comprising the steps of:

(1) Distribute aircraft corrosion environment monitoring devices on parts of the aircraft that are prone to corrosion, use them as sensor nodes, and add converging nodes to form a sensor network to monitor the corrosion environment of the entire structure in real time. The measured environmental parameters include temperature and relative humidity , wet time, value and concentration;

(2) When shutting down, the user collects data through the aggregation node and establishes a database;

(3) The user analyzes the data in the database, according to the empirical model Calculate the corrosion rate that the environment can cause, where is the corrosion rate, unit ; yes value; is the chloride ion concentration, unit ; is the wetting time, in units ; is temperature, unit ; is the relative humidity; is the coefficient of the empirical model, and the coefficient value suitable for the measured object is calculated from the data obtained from the corrosion test of the specimen;

(4) The corrosion rate obtained in step (3) and Comparing the environmental corrosivity grades divided in , that is, the health status of the aircraft can be evaluated from the perspective of corrosion, and based on this, it can be judged whether the aircraft needs to be maintained at the current stage.

A device for implementing a method for monitoring the corrosion environment of an aircraft, including a main control micro-control module, a measurement module, a communication module and a power supply module: the main control micro-control module is directly connected to the measurement module, and controls multiple sensors in the measurement module to monitor the environment in real time The parameters are measured; the main control micro-control module uses the built-in serial communication function components to directly connect with the conversion chip of the communication module to realize wired or wireless data communication with the outside world; the power supply module provides the work of the main control micro-control and measurement and communication modules Voltage.

The beneficial effects of the present invention are as follows:

The aircraft corrosion environment monitoring method proposed by the invention determines the corrosiveness level of the environment by measuring a plurality of environmental parameters that are likely to cause corrosion, thereby judging the health status of the aircraft structure and guiding the maintenance to take corresponding measures. The aircraft corrosion environment monitoring device involved is small in size and low in energy consumption, and is suitable for installation in various parts of the aircraft for long-term monitoring. The invention can change the current regular maintenance of the aircraft into on-demand maintenance, which improves the efficiency and reduces the cost.

Description of drawings

Figure 1 is a schematic diagram of the device of the present invention.

Figure 2(a) is the measurement circuit diagram of the wet time sensor; Figure 2(b) is the measurement circuit diagram of the electrochemical sensor.

Fig. 3 is a schematic diagram of the aircraft corrosion environment monitoring sensor network.

Fig. 4 is a flowchart of the steps of the monitoring method of the present invention.

detailed description

The invention will be described in further detail below in conjunction with the accompanying drawings.

Through the investigation and statistics of aircraft operating environment and ground parking environment spectrum, the environmental parameters affecting structural corrosion are analyzed. Temperature and humidity are the key factors for corrosion, but based on the working characteristics of aircraft, there are many reasons for its structural corrosion. For example, the wet state of the structure surface and the pollution of chlorides are also important factors for the corrosion of aerospace metals. exist When the concentration is high, if the chloride settles on the outer surface of the aircraft or stays inside with condensed water, it is easier to form an electrolyte solution to accelerate corrosion. In addition, affected by industrial pollution and aircraft exhaust, there are generally and . When the surface of the aircraft structure is wet, these pollution sources will dissolve or react with water, making the solution The value changes, which is also one of the causes of corrosion. Therefore, the present invention selects temperature, relative humidity, humidity time, value and Concentration of these five key parameters affecting the corrosion of aircraft structures was monitored for a long time. The monitoring of these parameters is accomplished by means of temperature and humidity sensors, humidity time sensors and electrochemical sensors, among which the humidity time sensors and electrochemical sensors are non-commercial sensors designed and manufactured for the present invention.

Temperature and humidity integrated sensor: here is the SMD package temperature and humidity sensor. The sensor integrates the sensing element and signal processing circuit on a tiny circuit board, and outputs a fully calibrated digital signal.

Wet Time Sensor: Wet time is the time that a metal surface remains wet when exposed to air. according to The definition of wetting time refers to the temperature at Above, the relative humidity is higher than time. The traditional measurement method is only to estimate the wetting time based on the temperature and relative humidity of the environment, which is somewhat different from the actual wetting time. A better method is to design sensors to monitor it. The present invention has produced resistive wet time sensor, adopts standard Manufacturing technology, two copper interdigitated electrodes separated from each other are produced on the epoxy resin board. In dry conditions, the two electrodes are not in contact with each other, and the output resistance of the sensor is infinite; when precipitation or water vapor condenses on the surface of the sensor, a path is formed between the electrodes, and the output resistance is greatly reduced. By measuring the resistance change of the sensor through a certain measuring circuit, the humidity time of the environment can be calculated. Some previous experimental data have verified that the smaller the sensor electrode spacing, the higher the sensor sensitivity. Therefore, the electrode spacing of the wet time sensor in this design is only , even if only a few micro-sized droplets are formed on the surface, they can be sensed. In addition, the sensor needs to be exposed to the external environment for a long time, and the copper electrode exposed to the air will be quickly damaged by corrosion, so the electrode is covered with a layer of gold for protection. The sensor is small in size, light in weight and long in life, and is suitable for use in the narrow space of the aircraft.

Electrochemical sensor: the present invention has also designed and manufactured an electrochemical sensor for monitoring Concentration and value, the measuring principle of this sensor is similar to the linear polarization technique. When the sensor is exposed to humid atmosphere or in a place with accumulated water, a water film will condense on its surface. This layer of water film dissolves salts or other impurities to form a certain Concentration and The value of the electrolyte solution provides conditions for electrochemical corrosion. When measuring, wait for the self-corrosion potential of the electrode to be stable and the electrode reaction to be in a balanced state; then apply a small voltage to the working electrode to polarize, the speed of the forward and reverse reactions will not be equal, and the polarization current will also change. When working, a scanning voltage is applied to the electrodes of the sensor, and the output current is monitored in real time. The previous experimental data demonstrated that when the electrolyte solution The higher the concentration or The smaller the value, the larger the current generated, and the environment can be obtained by monitoring the change of the current Concentration and value situation. Traditional measurement devices are all three-electrode systems, consisting of a working electrode, a reference electrode and an auxiliary electrode. The electrode process of the working electrode and the reference electrode is the same, their corrosion potential is similar, and the polarization time is very short, so the two electrodes can be made of the same material; and because the auxiliary electrode is only used for polarization Loop use can also be made of the same material. In addition, the present invention selects a wider electrode as a reference electrode and an auxiliary electrode at the same time, and a narrower electrode as a working electrode, that is, the two-electrode structure of the sensor, one wide and one narrow, replaces the traditional three-electrode structure. Therefore, the sensor is composed of The double-electrode grid structure made of duralumin is selected to be the same material as the monitored object in order to better present the corrosion status of the aircraft. During production, the epoxy resin plate is selected as the substrate, and a layer of duralumin film is firmly plated on it by evaporation technology, and then the pattern of the grid electrode is engraved on the surface by the pre-processed mask plate combined with photolithography technology. on the film. The electrodes of the sensor are a wide , a width , separated by . The sensor has a small size and the same material as the monitored object, and is suitable for application in corrosion monitoring of aircraft structures.

The measurement of environmental parameters requires the sensor to be in direct contact with the measured environment. For this reason, the overall layout of the device of the present invention is designed as upper and lower layers. The sensor and the corresponding measurement circuit are placed on the outer side of the upper layer, the sensor is exposed, and the measurement circuit part is protected by the packaging shell; the lower layer is the control circuit, which realizes the management of the entire device. The circuit connection between the upper and lower layers is carried out by pins, and at the same time it plays a fixed role. The whole device is small in size ( ), suitable for use in the narrow space of the aircraft.

Figure 1 is the overall schematic diagram of the device, which is composed of a main control micro-control module, a power supply module, a measurement module and a communication module. The above-mentioned sensors and their measurement circuits belong to the measurement module. The main control chip in the main control micro-control module is , the chip integrates a digital-to-analog conversion , analog-to-digital conversion and integrated circuit bus The module can control the sensor to complete the measurement of different parameters. The temperature and humidity sensor in the device outputs a digital signal, and the main control chip is connected to the sensor with two lines (data line, clock line). The protocol collects temperature and humidity data; while the humidity time and electrochemical sensors are analog measurements that require external excitation. The digital-to-analog converter of the main control chip is directly connected to the two sensors to provide excitation.

Figure 2 is a schematic diagram of the measurement circuit of the wet time and electrochemical sensor. Because these two sensors have working characteristics such as low trigger level, low output current, and large dynamic range of output signals, their measurement circuits need to be reasonably designed. The measurement circuit of the wet time sensor is shown in Figure 2(a), and the excitation voltage is applied to it , the resistance is converted into a voltage through the voltage divider circuit, and the voltage signal of the voltage divider circuit is amplified and filtered to obtain the output voltage . The measurement circuit of the electrochemical sensor is shown in Figure 2(b), and the excitation voltage is applied to it After the electrochemical reaction is stable, the polarization current generated between the two poles is measured, and the polarization current is converted into a voltage by the conversion circuit, and the output voltage is obtained after amplification and filtering. .

The above measurement circuit design pays special attention to the denoising and amplification of tiny signals: firstly, through a reasonable grounding design, to prevent errors caused by potential imbalance; secondly, use a low-bias operational amplifier to filter and amplify the sensor output signal; On the other hand, the bias of the sensor and circuit is eliminated by software compensation.

The output signal of the measurement circuit is directly connected to the digital-to-analog converter of the main control chip Connect to complete data collection and storage. The main control chip has of and of , together can store more than 2000 measurement data. If the measurement is set to be every 30 minutes, it can run continuously for 1000 hours before uploading to the client.

The whole monitoring device is powered by the power module, and the power supply battery passes through After DC conversion, the main control chip and measurement and communication modules provide working voltage. In terms of energy consumption, In addition, in this application, the environmental parameter monitored by the sensor is a physical quantity that changes very slowly, so it does not need to measure and send data frequently, and the corresponding average power is also very low. According to the needs, the sensor is regularly activated by the main control chip to enter the working state: measuring environmental parameters, signal conditioning, data storage and transmission; and in a dormant state for the rest of the time. This feature of low power consumption ensures the service life of the device.

This device is capable of data communication with the outside, Built-in two-way serial communication module, these two parts are connected with the conversion chip in the communication module, and can be implemented as required Or wireless communication.

When in use, in order to monitor the corrosion environment of the entire structure, the specific steps are shown in Figure 4. The device is distributed and installed in the parts of the aircraft that are prone to corrosion, and the environmental parameters are continuously collected, and the signal is stored locally after conditioning. If each monitoring device is regarded as a sensor node, then a sensor network is formed between them. In order to realize the communication between the whole system, in addition to each sensor node, it is also necessary to add a convergence node, as shown in Figure 3. The monitoring devices at different locations transmit local data to the aggregation node, and the aggregation node comprehensively manages each sensor node and uploads the data at an appropriate time. For example, when the machine is shut down, the user can use the handheld device, such as , notebooks, etc., get all the data through the aggregation node, and build a database.

The user stores the data in order to evaluate the corrosivity of the environment through the acquired environmental parameters, the method is as follows:

first, The standard gives the method of classifying the corrosiveness level of the environment, that is, the corrosiveness level is divided by measuring the corrosion rate of standard metals in a corrosive environment, such as zinc, as shown in Table 1.

Secondly, analyze the obtained measured environmental parameters, and estimate the corrosion rate that may be caused by the environment through the following empirical model:

in is the corrosion rate, unit ; yes value; is the chloride ion concentration, unit ; is the wetting time, in units ; is temperature, unit ; is the relative humidity; are the coefficients of each item in the model. After the specimen is exposed to the environment to be tested and corroded, the values of each coefficient can be obtained by calculating the obtained data.

Finally, compare the corrosion rate calculated by the above mathematical model with the data in Table 1 to obtain the environmental corrosivity level at this stage, and use this as a basis to guide the maintenance to judge whether the aircraft needs to be maintained at this stage.

Claims (2)

1. an aircraft corrosive environment monitoring method, is characterized in that, comprises the steps:

(1) the position distribution aircraft corrosive environment monitoring device corroded easily is there is at aircraft, using aircraft corrosive environment monitoring device as sensor node, and add convergence node formation sensor network, the corrosive environment of Real-Time Monitoring total, the environmental parameters of measurement comprise temperature, relative humidity, MEBO ribbon gauze, value and concentration;

(2), when shutting down, user collects data, building database by converging node;

(3) user is by the data in analytical database, rule of thumb model calculate the rate of corrosion that this environmental energy causes, wherein rate of corrosion, unit ; be value; chlorine ion concentration, unit ; mEBO ribbon gauze, unit ; temperature, unit ; relative humidity; be the coefficient of this empirical model, the data obtained by test specimen anticorrosive test calculate the coefficient value being suitable for measurand;

(4) rate of corrosion step (3) obtained with the corrosiveness of the environment grade of middle division compares, and can make assessment, and judge that present stage safeguards the need of to aircraft on this basis from the health status of angle to aircraft of corrosion.

2. the implement device of an aircraft corrosive environment monitoring method as claimed in claim 1, it is characterized in that, comprise master control micro control module, measurement module, communication module and power module: master control micro control module is directly connected with measurement module, the multiple sensors that control in measurement module are measured environmental parameters in real time; Master control micro control module utilizes built-in serial communication function parts to be directly connected with the conversion chip of communication module, realizes and extraneous wired or wireless data communication; Power module provides the operating voltage of master control micro-control and measurement, communication module.