An adaptive control system for relieving thermal stresses in aircraft structures

Abstract

The application belongs to the field of aeronautical structure thermal stress mitigation, and particularly relates to a self-adaptive control system for releasing the thermal stress of an aircraft structure. The system comprises a monitoring subsystem for obtaining a first monitoring signal; a signal processor for processing the first monitoring signal to obtain a second monitoring signal; and a control subsystem for adjusting the tightening torque of an electromagnetic control bolt according to the second monitoring signal. The control subsystem comprises a signal receiver, an intelligent control algorithm module, an electromagnetic controller and an electromagnetic control bolt. The signal receiver is configured to receive the second monitoring signal and send the second monitoring signal to the intelligent control algorithm module. The intelligent control algorithm module is configured to process the second monitoring signal to obtain a control signal. The electromagnetic controller is configured to adjust the tightening torque of the electromagnetic control bolt according to the control signal. The application can simultaneously meet the design requirements of aircraft connecting structures under low-temperature, normal-temperature and high-temperature environments.

Description

Technical Field

[0001] This application belongs to the field of aerospace structural thermal stress mitigation, and specifically relates to an adaptive control system for releasing thermal stress in aircraft structures. Background Technology

[0002] When an aircraft flies at sustained high Mach numbers, it experiences intense air compression and friction, converting a large amount of kinetic energy into heat. This causes a rapid increase in the temperature of the air surrounding the aircraft, ultimately leading to the expansion of the metal structure. The resulting thermal expansion and compression between the structures generates thermal stress. To release this stress, gaps are incorporated into some of the aircraft's connecting structures.

[0003] Currently, engineering practices employ enlarged or oblong hole connections to release thermal stress. While this method is beneficial for stress relief, in low-temperature environments, large gaps can reduce the structural stiffness, leading to localized loads and stress spikes. Furthermore, in low-temperature environments, gaps between aircraft connections can cause localized dynamic stress due to collisions during vibrations if these gaps are too small. Conversely, excessively large gaps can persist even after thermal expansion, resulting in continued thermal stress at high temperatures. Theoretically, these problems can be avoided by increasing the stiffness of local connections through tightening bolts or by designing appropriately sized gaps. However, designing suitable tightening torques and gaps is extremely difficult. This is because the aerodynamic load, temperature, and engine vibration environments in the air are highly complex and difficult to predict accurately. Additionally, the temperature and load environments at each gap connection location differ, making it challenging for designers to optimize the design using simulations to obtain appropriately sized gaps.

[0004] Therefore, it is desirable to have a technical solution to overcome or at least mitigate one of the aforementioned defects of the prior art. Summary of the Invention

[0005] The purpose of this application is to provide an adaptive control system for relieving thermal stress in aircraft structures, thereby solving at least one problem existing in the prior art.

[0006] The technical solution of this application is:

[0007] An adaptive control system for relieving thermal stress on an aircraft structure, comprising:

[0008] The monitoring subsystem is used to acquire the first monitoring signal;

[0009] A signal processor is used to process the first monitoring signal to obtain a second monitoring signal;

[0010] A control subsystem is used to adjust the tightening torque of the electromagnetic control bolt according to the second monitoring signal. The control subsystem includes a signal receiver, an intelligent control algorithm module, an electromagnetic controller, and an electromagnetic control bolt.

[0011] The signal receiver is used to receive the second monitoring signal and send the second monitoring signal to the intelligent control algorithm module;

[0012] The intelligent control algorithm module is used to process the second monitoring signal to obtain a control signal;

[0013] The electromagnetic controller is used to adjust the tightening torque of the electromagnetic control bolt according to the control signal.

[0014] In at least one embodiment of this application, the monitoring subsystem includes a strain sensor and a vibration acceleration sensor, wherein,

[0015] The strain sensor is arranged on the aircraft connection structure to acquire the first strain signal;

[0016] The vibration acceleration sensor is arranged on the aircraft connection structure to acquire the first vibration acceleration signal.

[0017] In at least one embodiment of this application, the signal processor processes the first monitoring signal by means of filtering and noise reduction.

[0018] In at least one embodiment of this application,

[0019] The signal processor processes the first strain signal to obtain a second strain signal;

[0020] The signal processor processes the first vibration acceleration signal to obtain a second vibration acceleration signal.

[0021] In at least one embodiment of this application, the control subsystem adjusts the tightening torque of the electromagnetic control bolt according to the second monitoring signal, including:

[0022] The signal receiver sends the received second strain signal and second vibration acceleration signal to the intelligent control algorithm module;

[0023] The intelligent control algorithm module processes the second strain signal and the second vibration acceleration signal to obtain control signals, including:

[0024] A first control signal is generated based on the second strain signal:

[0025]

[0026] A second control signal is generated based on the second vibration acceleration signal:

[0027]

[0028] Calculate the difference between the second control signal and the first control signal:

[0029] E(t)=F a (t)-F ε (t)

[0030] A control signal is generated based on the difference between the second control signal and the first control signal:

[0031]

[0032] Among them, F ε (t) represents the first control signal output by the strain response, F a (t) represents the second control signal output by the vibration acceleration response, K ε K is the proportional coefficient for strain control. a E is the proportional coefficient for vibration acceleration control. ε (t) represents the difference between the first control signal and the target stable value, E a (t) represents the difference between the second control signal and the target stable value, T εi T is the strain integral time constant. ai T is the integral time constant of vibration acceleration. εd T is the differential time constant of strain. ad Let F(t) be the differential time constant of the vibration acceleration, and K be the control signal output by the integrated control. p T is the proportional coefficient for integrated control. i For the integrated control integral time constant, T d To control the differential time constant;

[0033] The electromagnetic controller adjusts the tightening torque of the electromagnetic control bolt according to the control signal.

[0034] In at least one embodiment of this application,

[0035] During the initial stage of the aircraft's climb, the electromagnetic controller increases the tightening torque of the electromagnetic control bolt according to the control signal;

[0036] During the final stage of the aircraft's climb, the electromagnetic controller first reduces the tightening torque of the electromagnetic control bolt according to the control signal, and then increases the tightening torque of the electromagnetic control bolt according to the control signal.

[0037] In at least one embodiment of this application,

[0038] During the aircraft's descent phase, the electromagnetic controller first reduces the tightening torque of the electromagnetic control bolt according to the control signal, and then increases the tightening torque of the electromagnetic control bolt according to the control signal.

[0039] The invention has at least the following beneficial technical effects:

[0040] The adaptive control system for releasing thermal stress in aircraft structures in this application can simultaneously meet the design requirements of aircraft connection structures under low temperature, normal temperature and high temperature environments. It can effectively reduce structural thermal stress while ensuring that the connection structure has sufficient connection stiffness, and prevent problems such as excessive local stress and collision of the connection structure. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of an adaptive control system for releasing thermal stress in an aircraft structure according to one embodiment of this application. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0043] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this application.

[0044] The following is in conjunction with the appendix Figure 1 This application will be described in further detail.

[0045] This application provides an adaptive control system for relieving thermal stress in an aircraft structure, comprising: a monitoring subsystem, a signal processor, and a control subsystem.

[0046] Specifically, the monitoring subsystem is used to acquire a first monitoring signal; the signal processor is used to process the first monitoring signal to obtain a second monitoring signal; the control subsystem is used to adjust the tightening torque of the electromagnetic control bolt according to the second monitoring signal. The control subsystem includes a signal receiver, an intelligent control algorithm module, an electromagnetic controller, and an electromagnetic control bolt. The signal receiver is used to receive the second monitoring signal and send it to the intelligent control algorithm module; the intelligent control algorithm module is used to process the second monitoring signal to obtain a control signal; and the electromagnetic controller is used to adjust the tightening torque of the electromagnetic control bolt according to the control signal.

[0047] In a preferred embodiment of this application, the monitoring subsystem includes a strain sensor and a vibration acceleration sensor. The strain sensor is positioned near the aircraft connection structure to acquire a first strain signal in real time; the vibration acceleration sensor is positioned near the aircraft connection structure to acquire a first vibration acceleration signal in real time. By strategically arranging monitoring points, the mechanical state of the aircraft connection structure is monitored in real time. The leads of the strain sensor and the vibration acceleration sensor are connected to a signal processor, which is then connected to a signal receiver. A signal converter is connected to the control subsystem and supplies power to the system. The signal processor processes the first monitoring signal, including but not limited to filtering and noise reduction. The signal processor processes the first strain signal to obtain a second strain signal, and the signal processor processes the first vibration acceleration signal to obtain a second vibration acceleration signal. The signal receiver transmits the received real-time strain and vibration acceleration response signals from the aircraft connection structure to the intelligent control algorithm module. The intelligent control algorithm module analyzes, processes, and calculates the response signals and issues commands to the electromagnetic controller. The electromagnetic controller then adjusts the tightening torque of the electromagnetic control bolts using electromagnetic torque.

[0048] The adaptive control system for releasing thermal stress in aircraft structures disclosed in this application includes a control subsystem that adjusts the tightening torque of electromagnetic control bolts based on a second monitoring signal, comprising:

[0049] The signal receiver sends the received second strain signal and second vibration acceleration signal to the intelligent control algorithm module;

[0050] The intelligent control algorithm module processes the second strain signal and the second vibration acceleration signal to obtain control signals, including:

[0051] A first control signal is generated based on the second strain signal:

[0052]

[0053] A second control signal is generated based on the second vibration acceleration signal.

[0054]

[0055] Calculate the difference between the second control signal and the first control signal:

[0056] E(t)=F a (t)-F ε (t)

[0057] A control signal is generated based on the difference between the second control signal and the first control signal:

[0058]

[0059] Among them, F ε (t) represents the first control signal output by the strain response, F a (t) represents the second control signal output by the vibration acceleration response, K ε K is the proportional coefficient for strain control. a E is the proportional coefficient for vibration acceleration control. ε (t) represents the difference between the first control signal and the target stable value, E a (t) represents the difference between the second control signal and the target stable value, T εi T is the strain integral time constant. ai T is the integral time constant of vibration acceleration. εd T is the differential time constant of strain. ad Let F(t) be the differential time constant of the vibration acceleration, and K be the control signal output by the integrated control. p T is the proportional coefficient for integrated control. i For the integrated control integral time constant, T d To control the differential time constant;

[0060] The electromagnetic controller adjusts the tightening torque of the electromagnetic control bolt according to the control signal.

[0061] The adaptive control system for releasing thermal stress in aircraft structures in this application employs a dual-layer PID control algorithm in its intelligent control algorithm module. First, it calculates the control output signal based on the strain response and vibration acceleration response, then it calculates the difference between the control output signals for vibration acceleration and strain, and finally, it uses an outer layer control algorithm to keep the acceleration control output signal and the strain control output signal consistent, and provides a comprehensive control output signal.

[0062] In this embodiment, during the initial stage of aircraft climb, the electromagnetic controller increases the tightening torque of the electromagnetic control bolt according to the control signal; during the final stage of aircraft climb, the electromagnetic controller first decreases the tightening torque of the electromagnetic control bolt according to the control signal, and then increases the tightening torque of the electromagnetic control bolt according to the control signal.

[0063] The adaptive control system for releasing thermal stress in aircraft structures disclosed in this application operates as follows: During the initial climb phase, when the ambient temperature is low and strain and vibration acceleration signals are at low levels, the control subsystem increases electromagnetic torque to tighten the electromagnetic control bolts, ensuring structural connection stiffness and enabling normal force transmission in the aircraft connection structure. As the aircraft continues to climb, the intense friction between the fuselage structure and the atmosphere generates a large amount of heat, causing a rapid increase in the temperature of the aircraft connection structure. At this time, strain and vibration acceleration signals are at high levels, and the control subsystem reduces the electromagnetic tightening torque to release the thermal stress in the aircraft connection structure. After the thermal stress is released, the control subsystem tightens the bolts again to ensure sufficient connection stiffness and prevent localized failure to transmit force. The change in the electromagnetic control bolt tightening torque alters the strain and vibration acceleration of the gap connection structure; subsequently, the signal converter transmits a new set of strain and vibration acceleration signals to the signal receiver, repeating the above process until the strain and acceleration signals stabilize within the design requirements.

[0064] In this embodiment, during the aircraft's descent phase, the electromagnetic controller first reduces the tightening torque of the electromagnetic control bolt according to the control signal, and then increases the tightening torque of the electromagnetic control bolt according to the control signal.

[0065] The adaptive control system for releasing thermal stress in aircraft structures disclosed in this application operates as follows: During the aircraft's descent, as the ambient temperature gradually decreases and strain and vibration acceleration signals remain at relatively high levels, the control subsystem reduces the electromagnetic tightening torque to decrease the structural connection stiffness, allowing the structure to cool and shrink back to its original connection position. Once the structure has returned to its original position, and strain and vibration acceleration signals remain at relatively low levels, the control subsystem increases the electromagnetic torque to tighten the bolts again. This change in the electromagnetic bolt tightening torque alters the strain and vibration acceleration of the gap connection structure. Subsequently, the signal converter transmits a new set of strain and vibration acceleration signals to the signal receiver, repeating the above process until the strain and acceleration signals stabilize within the design requirements.

[0066] The adaptive control system for releasing thermal stress in aircraft structures disclosed in this application can adaptively adjust the tightening torque at the connection position in real time based on the response data near the monitoring gap connection structure. This ensures that the aircraft connection structure meets the requirements for thermal stress release, force transmission, and dynamic strength under different temperature and load environments. This system can ensure that the aircraft connection structure meets design requirements in low-temperature, normal-temperature, and high-temperature environments by adjusting the bolt preload at the connection position in real time. Simultaneously, this system reduces design complexity. By intelligently controlling the tightness of the connection gap, designers no longer need to accurately predict the structural vibration, structural temperature, and other load environments of the aircraft connection structure, and can design connection gaps and bolt tightening torques with precise dimensions.

[0067] The adaptive control system for releasing thermal stress in aircraft structures, as described in this application, can effectively reduce structural thermal stress while ensuring sufficient connection stiffness to prevent problems such as excessive local stress and collisions between connected structures. Unlike traditional thermal stress release designs, this system exhibits excellent robustness and can adapt to initial designs with different gap sizes and bolt preloads. The adaptive control algorithm matches the optimal tightening torque for the gap connection based on monitoring point signals, and the control subsystem can find the optimal thermal stress release scheme in real time based on the structural response under different vibration and temperature environments. The system is simple in principle and highly versatile; in addition to releasing thermal stress in connected structures, it can also be used to reduce structural vibration response and adjust the force transmission path.

[0068] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An adaptive control system for relieving thermal stress in aircraft structures, characterized in that, include: The monitoring subsystem is used to acquire the first monitoring signal; A signal processor is used to process the first monitoring signal to obtain a second monitoring signal; The control subsystem includes a signal receiver, an intelligent control algorithm module, an electromagnetic controller, and an electromagnetic control bolt. The control subsystem is used to adjust the tightening torque of the electromagnetic control bolt according to the second monitoring signal. The signal receiver is used to receive the second monitoring signal and send the second monitoring signal to the intelligent control algorithm module; The intelligent control algorithm module is used to process the second monitoring signal to obtain a control signal; The electromagnetic controller is used to adjust the tightening torque of the electromagnetic control bolt according to the control signal; The monitoring subsystem includes strain sensors and vibration acceleration sensors, wherein, The strain sensor is arranged on the aircraft connection structure to acquire the first strain signal; The vibration acceleration sensor is arranged on the aircraft connection structure to acquire the first vibration acceleration signal; The signal processor processes the first strain signal to obtain a second strain signal; The signal processor processes the first vibration acceleration signal to obtain a second vibration acceleration signal; The control subsystem adjusts the tightening torque of the electromagnetic control bolt according to the second monitoring signal, including: The signal receiver sends the received second strain signal and second vibration acceleration signal to the intelligent control algorithm module; The intelligent control algorithm module processes the second strain signal and the second vibration acceleration signal to obtain control signals, including: A first control signal is generated based on the second strain signal: ； A second control signal is generated based on the second vibration acceleration signal: ； Calculate the difference between the second control signal and the first control signal: ； A control signal is generated based on the difference between the second control signal and the first control signal: ； in, The first control signal output is the strain response. The second control signal is the output of the vibration acceleration response. This is the proportional coefficient for strain control. This is the proportional coefficient for vibration acceleration control. The difference between the first control signal and the target stable value. The difference between the second control signal and the target stable value. Let be the strain integral time constant. Let be the integral time constant of the vibration acceleration. The time constant is the differential strain. Let be the differential time constant of the vibration acceleration. The control signal output for comprehensive control. The proportional coefficient for comprehensive control. To achieve the integrated control time constant, To control the differential time constant; The electromagnetic controller adjusts the tightening torque of the electromagnetic control bolt according to the control signal.

2. The adaptive control system for releasing thermal stress in aircraft structures according to claim 1, characterized in that, The signal processor processes the first monitoring signal by means of filtering and noise reduction.

3. The adaptive control system for releasing thermal stress in aircraft structures according to claim 2, characterized in that, During the initial stage of the aircraft's climb, the electromagnetic controller increases the tightening torque of the electromagnetic control bolt according to the control signal; During the final stage of the aircraft's climb, the electromagnetic controller first reduces the tightening torque of the electromagnetic control bolt according to the control signal, and then increases the tightening torque of the electromagnetic control bolt according to the control signal.

4. The adaptive control system for releasing thermal stress in aircraft structures according to claim 3, characterized in that, During the aircraft's descent phase, the electromagnetic controller first reduces the tightening torque of the electromagnetic control bolt according to the control signal, and then increases the tightening torque of the electromagnetic control bolt according to the control signal.

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